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Synthesis of stereoregular non-conjugated pendant electroactive polymers

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Synthesis of stereoregular non-conjugated pendant electroactive polymers

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SYNTHESIS OF STEREOREGULAR NON-CONJUGATED PENDANT
ELECTROACTIVE POLYMERS

by
Alexander Schmitt

A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(CHEMISTRY)

May 2023

Copyright 2023 Alexander Schmitt

ii

Dedication

To my family and friends

iii

Acknowledgements

I would first like to thank my parents for their love and guidance throughout my life for which
I am forever grateful. You have both inspired me in so many ways and I know that without your
support this would not have been possible.
Next I want to thank my doctoral advisor, Prof. Barry C. Thompson. Without your advice and
consistent support this work would not have been possible. It was thanks to the professional,
collaborative and welcoming environment you have created in your group that I was able to
explore many new avenues of chemistry and devlop not only scientifically and professionally but
also personally.
Furthermore, I would like to acknowledge the members of my PhD committee, Prof. Sri
Narayan and Prof. Sarah Feakins, as well as Prof. Valery Fokin and Prof. Nicos Petasis who were
serving on my qualifying committee, for their insightful comments and encouragement. To Dr.
Robert Pankow, Dr. Sanket Samal, Dr. Liwei Ye, Dr. Pratyusha Das and Dr. Negar Kazerouni, I
want to thank you all for your training and assistance in the lab, for always patiently answering
my many questions and fostering an exceptionally welcoming and supportive atmosphere in the
group. I would like to give a special thanks to Robert for his support during my early years and
also to Sanket for his enormous support in training me on the project for this thesis, you both have
been great friends throughout my time at graduate school. Additionally, I would like to thank my
current group members, Tanin Hooshmand, Grace Castillo, Timothy Bennett, Steve Sheppard,
Dhairya Patel and especially Qingpei Wan for being great colleagues and friends, it has truly been
a great experience working with you all.
iv

Besides the academic support, I want to thank my great friends back home and all the amazing
friends I was able to meet through my time here at USC that have made graduate school such a
great experience; I do not want to attempt a comprehensive list but you know who you are. I could
not be writing this without all of your support and I cannot begin to express my gratitude for your
frienship. Finally, I want to thank my partner Mitchell who over the better part of the last three
years has been the most loving support in not just my academic career but well beyond and I could
not be more grateful that he is a part of my life.
The work in this dissertation would not have been possible without the assistance of the
following individuals: Dr. Negar Kazerouni (polymer characterizations in Chapters 2, 4), Qinpei
Wan (polymer characterizations in Chapter 3) and Grace Castillo (polymer synthesis in
Chapter 2).

v

Table of Contents

Dedication ...................................................................................................................................... ii
Acknowledgements ........................................................................................................................ iii
List of Tables ................................................................................................................................. ix
List of Figures ................................................................................................................................ xi
List of Schemes .......................................................................................................................... xxvi
Abstract xxvii
Chapter 1: Relating Structure to Properties in Non-Conjugated Pendant Electroactive Polymers 1
1.1 Introduction ................................................................................................................... 1
1.2 Structure-property relationships in NCPEPs .............................................................. 11
1.2.1 Poly(vinyl) NCPEPs ........................................................................................ 11
1.2.1.1 Homopolymers of poly(vinyl) NCPEPs ....................................................... 11
1.2.2 Poly(styrene) NCPEPs ..................................................................................... 21
1.2.3 Poly(acrylate) NCPEPs .................................................................................... 47
1.2.4 Poly(methacrylate) NCPEPs ............................................................................ 64
1.2.5 Poly(norbornene) NCPEPs .............................................................................. 77
1.3 Conclusion .................................................................................................................. 81
1.4 References ................................................................................................................... 84
Chapter 2: Synthesis of Block Copolymers Containing Stereoregular Pendant Electroactive
Blocks ......................................................................................................................... 95
2.1 Introduction ................................................................................................................. 95
2.2 Experimental ............................................................................................................... 97
2.3 Results and Discussion ............................................................................................. 102
vi

2.4 Conclusion ................................................................................................................ 107
2.5 References ................................................................................................................. 108
Chapter 3: Stereoregular Pendant Electroactive Polymers with Extended Pendants via Post-
Polymerization Copper Catalyzed Azide-Alkyne Cycloaddition ............................. 111
3.1 Introduction ............................................................................................................... 111
3.2 Synthesis ................................................................................................................... 114
3.3 Results and Discussion ............................................................................................. 117
3.4 Results and Discussion ............................................................................................. 122
3.5 References ................................................................................................................. 123
Chapter 4: Impact of Pendant Substituents on Post-Polymerization Functionalization and
Electronic Properties in Stereoregular Non-Conjugated Electroactive Pendant
Polymers ................................................................................................................... 127
4.1 Introduction ............................................................................................................... 127
4.2 Results and Discussion ............................................................................................. 130
4.3 Conclusion ................................................................................................................ 140
4.4 References ................................................................................................................. 141
Biographical Sketch .................................................................................................................... 145
Appendices .................................................................................................................................. 146
Appendix A: Synthesis of Block Copolymers Containing Stereoregular Pendant
Electroactive Blocks ....................................................................................................... 146
A.1 Materials and Methods ..................................................................................... 146
A.2 Synthetic Procedures ........................................................................................ 149
A.3
1
H-NMR spectra of the Polymers ............................................................................ 160
A.4 GPC Traces ...................................................................................................... 170
A.5 UV-Vis Absorption Data ................................................................................. 175
vii

A.6 Photoluminescence Data .................................................................................. 177
A.7 DSC Data ......................................................................................................... 179
A.8 Mobility Data ................................................................................................... 188
A.9 References ........................................................................................................ 188
Appendix B: Stereoregular Pendant Electroactive Polymers with Extended Pendants
via Post-Polymerization Copper Catalyzed Azide-Alkyne Cycloaddition ..................... 189
B.1 Materials and Methods ..................................................................................... 189
B.2 Synthetic Procedures ........................................................................................ 192
B.3 Characterization of Polymers ........................................................................... 205
B.4 Failed Post-Polymerization Functionalizations ................................................ 211
B.5 GPC Traces ...................................................................................................... 228
B.6 Differential Scanning Calorimetry ................................................................... 230
B.7 UV/Vis Spectroscopy ....................................................................................... 232
B.8 Photoluminescence Data .................................................................................. 234
B.9 Mobility Data ................................................................................................... 235
B.10 References ...................................................................................................... 236
Appendix C: Impact of Pendant Substituents on Post-Polymerization
Functionalization and Electronic Properties in Stereoregular Non-Conjugated
Pendant Electroactive Polymers ..................................................................................... 238
C.1 Materials and Methods ..................................................................................... 238
C.2 Synthetic Procedures ........................................................................................ 241
C.3 Polymer Characterization ................................................................................. 253
viii

C.3 Attempted thiol-ene functionalizations with 2-(3,6-disubstituted-9H-
carbazol-9-yl)ethane-1-thiols for phenyl, methoxy and nitrile as the respective
substituents:............................................................................................................. 257
C.4 Differential Scanning Calorimetry ................................................................... 269
C.5 UV/Vis Absorption Data .................................................................................. 272
C.6 Photoluminescence Data .................................................................................. 273
C.7 Mobility Data ................................................................................................... 274
C.8 Simulations ....................................................................................................... 274
C.9 References ........................................................................................................ 277

ix

List of Tables
Table 1.1 General monomer structures and their corresponding polymer structures that make
up the backbone of the respective NCPEPs. ................................................................................. 10
Table 2.1 Molecular Weights, Polydispersities, Polymer Yields/Conversions, Triad
Tacticities and PS-to-PAMA Block Ratios for the Family of PS-b-PCzETPMA Polymers. ..... 100
Table 3.1 Molecular Weights, Dispersities, Polymer Yields/Conversions and Triad
Tacticities for the Family of Polymers........................................................................................ 116
Table 4.1 Molecular Weights, Dispersities, Polymer Yields/Conversions and Triad
Tacticities for the Family of Polymers........................................................................................ 133
Table A.1 Polymerization conditions and yields for block-copolymers B1u-B9u. .................... 150
Table A.2 Characterization data for block copolymers B1u-B9u. .............................................. 150
Table A.3 Molecular weights, dispersities and tacticities for the PS and the PAMA
homopolymer. ............................................................................................................................. 152
Table A.4 Reaction conditions for the thiol-ene photoreactions yielding the functionalized
block-copolymers B1f-B9f and their characterization data. . ...................................................... 150
Table A.5 Hole mobilities μh both unannealed and annealed at 150 °C for 30 min in air and
film thicknesses for all copolymers. ........................................................................................... 220
Table B.1 Characterization data for P1. ...................................................................................... 205
Table B.2 Characterization data for functionalized polymers P3-P5 after click reaction. ........ 205
x

Table B.3 Hole mobilities μh both unannealed and annealed at 150 °C and 210 °C for 30
min in air and film thicknesses for all copolymers. ................................................................... 236
Table C.1 Molecular weights, dispersities, yield and triad tacticities for parent PAMA
homopolymers. ........................................................................................................................... 254
Table C.2 Conversions, molecular weights and polydispersities for the functionalized
PCzETPMA polymers. ............................................................................................................... 254
Table C.3 Reaction conditions for the thiol-ene reactions of atactic PAMA with 2-(3,6-
dimethoxy-9H-carbazol-9-yl)ethane-1-thiol. .............................................................................. 262
Table C.4 Hole mobilities μh both unannealed and annealed at 150 °C for 30 min in air and
film thicknesses for all polymers. ............................................................................................... 274

xi

List of Figures
Figure 1.1 Exemplary structures of CPs used as the active material in various organic
electronic applications. .................................................................................................................. 3
Figure 1.2 General schematic structure of NCPEPs. . .................................................................... 6
Figure 1.3 a) Exemplary synthesis schemes for functionalization of NCPEPs by
transesterification via the two general synthetic routes: (1) polymerization of fully
functionalized monomers and (1) polymerization of the backbone followed by a post-
polymerization with the respective pendant group. b) Advanced NCPEP architectures shown
schematically for a NCPEP with a simple polyvinyl backbone and a carbazole pendant group
(blue). .............................................................................................................................................. 7
Figure 1.4 a) Chemical structure of poly(vinyl) derived NCPEP homopolymers. b) PL spectra
of iso-PPK and syn-PPK films under an excitation wavelength of 298 nm. ................................ 14
Figure 1.5 Chemical structures of poly(vinyl) based NCPEP copolymers and of PDBF
copolymers. ................................................................................................................................... 29
Figure 1.6 a) Chemical structures of poly(styrene) derived NCPEP homopolymers. b)
Normalized absorption and emission spectra of poly(2,7-bis(MePh)An-Cz-styrene) (black)
and poly(3,6-bis(MePh)An-Cz-styrene) (red). ............................................................................. 25
Figure 1.7 a) Chemical structures of poly(styrene) derived NCPEP copolymers. b) Cross
sectional transmission electron micrographs of block copolymers PvDMTPA-b-PPerAcr
(a), PvDMTPA-b-PPerAcr (b) and PvDMTPD-b-PPerAcr (c). The samples were tempered
at 210 °C, embedded in epoxy resin, cut and stained with RuO4. c) AFM topography images
xii

showing films of P4MS-co-P4(PCBM)S (30 (1), 37 (2) and 51 wt.-% PCBM (3)) and blends
of PCBM:PS-OH in varying compositions (30, 40, 50 wt.-% PCBM) prepared for the SCLC
measurements………………………………………………..…………………………………..44
Figure 1.8 a) Chemical structures of poly(acrylate) derived NCPEP homopolymers. b)
Relationship of hole mobilities for as-cast and annealed PCzEAs with increasing degrees of
isotacticity. c) Relationship of hole mobilities for two families of as-cast and annealed
PCzXAs with different degrees of isotacticity with spacer lengths ranging from 2 to 12
carbons. ........................................................................................................................................ 51
Figure 1.9 a) General structure of poly(acrylate) derived NCPEP copolymers. b) TEM
images of PS-b-PPerAcr1 (a), PS-b-PPerAcr2 (b) and PS-b-PPerAcr3 (c); the samples were
annealed for 210 °C for 1h, embedded into epoxy resin, cut, and stained with RuO4. Top-
view SEM images of films of PS-b-PPerAcr1 (d), PS-b-PPerAcr2 (e) and PS-b-PPerAcr3 (f);
the samples were annealed at 210 °C for 1h and film thicknesses were around 150 nm. c)
Top-view SEM images of (g), PS:PPerAcr homopolymer blend as cast (h) and PS:PPerAcr
homopolymer blend after annealing at 210 °C for 1h (i). ............................................................. 61
Figure 1.10 General structure of poly(methacrylate) derived NCPEP homopolymers. ............... 67
Figure 1.11 Chemical structures of poly(methacrylate) derived copolymers with one
electroinactive comonomer and of PMEMA-co-P(Y)s exclusively featuring electroactive
monomers. ..................................................................................................................................... 71
Figure 1.12 Chemical structures of poly(methacrylate) derived copolymers exclusively
containing electroactive comonomers........................................................................................... 73
xiii

Figure 1.13 a) Chemical structures of poly(norbene) derived NCPEPs. b) Electric-field
dependence of the hole mobilities of PBPMMA (diamonds) and PBPMMN (triangles)
measured as a function of electric field at 299 K; symbols represent experimental data,
lines are linear fits according to the disorder formalism. ............................................................. 78
Figure 2.1 Increasing complexity of NCPEP architecture when transitioning from linear
homopolymers to block-copolymers............................................................................................. 97
Figure 2.2 (a) PL spectra of PS-b-PCzETPMA copolymers B5f-B9f for as-cast films. (b) PL
spectra of PS-b-PCzETPMA copolymers B5f-B9f after annealing at 150 °C for 30 min. ......... 104
Figure 2.3 Hole mobilities of copolymers B5f-B9f as cast and after annealing at 150 °C for
30 min. ....................................................................................................................................... 105
Figure 3.1 Compatability of post-polymerization functionalization methods with 3,6-bis(4-
(2-ethylhexyl)thiophen-2-yl)-carbazole. ..................................................................................... 114
Figure 3.2 (a) PL spectra of P3-P5 in as-cast fimls. (b) PL spectra of P3-P5 after annealing at
150 °C for 30 min. ..................................................................................................................... 119
Figure 3.3 Hole mobilities of polymers P3-P5 as cast and after annealing at 150 °C for 30
min and 210 °C for 30 min. ....................................................................................................... 121
Figure 4.1 Extending the carbazole pendant group of PCzETPMA to various 3,6-
disubstituted carbazoles. ............................................................................................................. 129
Figure 4.2 a) PL spectra of PCzETPMAs for as-cast films. (b) PL spectra for PCzETPMAs
after annealing at 150 °C for 30 min.. ......................................................................................... 135
xiv

Figure 4.3 Hole mobilities of PCzETPMA polymer with Cz and tBuCz pendant groups as
cast and after annealing at 150 °C for 30 min. ............................................................................ 137
Figure 4.4 a) DFT-optimized structures of Cz-polymers with 40 repeating units and
highlighted polymer backbone. Reprinted with permission from Samal et al.
11
Copyright
2021 American Chemical Society. b) DFT-optimized structures of tBuCz-polymers with 40
repeating units and highlighted polymer backbone. ................................................................... 139
Figure A.1
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the polystyrene homopolymer
listed in table A3. ........................................................................................................................ 153
Figure A.2
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the poly(allyl methacrylate)
homopolymer listed in table A3. ................................................................................................. 154
Figure A.3
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the physical mixture of the
polystyrene and poly(allyl methacrylate) homopolymers listed in table A3. ............................ 154
Figure A.4
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the filtrate of the homopolymers
listed in table A3 after stirring in hot Acetone. ........................................................................... 155
Figure A.5
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the filtered off solids from the
physical mixture of the homopolymers listed in table A3 after stirring in hot Acetone. ............ 156
Figure A.6
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of block-copolymer B9u after stirring
in hot Acetone. ........................................................................................................................... 156
xv

Figure A.7 GPC traces of the PS homopolymer listed in table A3 (top left), the PAMA
homopolymer listed in table A3 (top right) and the physical mixture of the two after
precipitation in cold MeOH (bottom). ........................................................................................ 157
Figure A.8 GPC traces of the filtrate (left) and filtered off solids (right) after stirring the
physical mixture of the PS and PAMA homopolymers listed in table A3 in hot Acetone and
filtering them. .............................................................................................................................. 158
Figure A.9 GPC traces of the filtered off block-copolymer B9u after stirring it in cold MeOH
(left) and in hot Acetone (right). ................................................................................................. 158
Figure A.10
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B1f. ............................................... 160
Figure A.11
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B1u. ............................................... 161
Figure A.12
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B2f. ............................................... 161
Figure A.13
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B2u. ............................................... 162
Figure A.14
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B3f. ............................................... 162
Figure A.15
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B3u. ............................................... 163
Figure A.16
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B4f. ............................................... 163
Figure A.17
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B4u. ............................................... 164
Figure A.18
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B5f. ............................................... 164
Figure A.19
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B5u. ............................................... 165
xvi

Figure A.20
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B6f. ............................................... 165
Figure A.21
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B6u. ............................................... 166
Figure A.22
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B7f. ............................................... 166
Figure A.23
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B7u. ............................................... 167
Figure A.24
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B8f. ............................................... 167
Figure A.25
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B8u. ............................................... 168
Figure A.26
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B9f. ............................................... 168
Figure A.27
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B9u. ............................................... 169
Figure A.28 GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer (top
right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B1. ................. 170
Figure A.29 GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer (top
right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B2. ................. 170
Figure A.30 GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer (top
right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B3. ................. 171
Figure A.31 GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer (top
right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B4. ................. 171
Figure A.32 GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer (top
right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B5. ................. 172
xvii

Figure A.33 GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer (top
right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B6. ................. 172
Figure A.34 GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer (top
right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B7. ................. 173
Figure A.35 GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer (top
right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B8. ................. 173
Figure A.36 GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer (top
right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B9. ................. 174
Figure A.37 UV/Vis absorption spectra of as cast low molecular weight copolymers B1f-B4f. 175
Figure A.38 UV-Vis absorption spectra of low molecular weight copolymers B1f-B4f after
annealing at 150 °C for 30 min. .................................................................................................. 175
Figure A.39 UV-Vis absorption spectra of as cast high molecular weight copolymers
B5f-B9f. ....................................................................................................................................... 176
Figure A.40 UV-Vis absorption spectra of high molecular weight copolymers B5f-B9f after
annealing at 150 °C for 30 min. .................................................................................................. 176
Figure A.41 PL emission spectra of as cast low molecular weight copolymers B1f-B4f. ......... 177
Figure A.42 PL emission spectra of low molecular weight copolymers B1f-B4f after
annealing at 150 °C for 30 min. .................................................................................................. 177
Figure A.43 PL emission spectra of as cast high molecular weight copolymers B5f-B9f. ......... 178
xviii

Figure A.44 PL emission spectra of high molecular weight copolymers B5f-B9f after
annealing at 150 °C for 30 min. .................................................................................................. 178
Figure A.45 DSC scan of polymer B1u. ...................................................................................... 179
Figure A.46 DSC scan of polymer B2u. ...................................................................................... 179
Figure A.47 DSC scan of polymer B3u. ...................................................................................... 180
Figure A.48 DSC scan of polymer B4u. ...................................................................................... 180
Figure A.49 DSC scan of polymer B5u. ...................................................................................... 181
Figure A.50 DSC scan of polymer B6u. ...................................................................................... 181
Figure A.51 DSC scan of polymer B7u. ...................................................................................... 182
Figure A.52 DSC scan of polymer B8u. ...................................................................................... 182
Figure A.53 DSC scan of polymer B9u. ...................................................................................... 183
Figure A.54 DSC scan of polymer B1f. ...................................................................................... 183
Figure A.55 DSC scan of polymer B2f. ...................................................................................... 184
Figure A.56 DSC scan of polymer B3f. ...................................................................................... 184
Figure A.57 DSC scan of polymer B4f. ...................................................................................... 185
Figure A.58 DSC scan of polymer B5f. ...................................................................................... 185
Figure A.59 DSC scan of polymer B6f. ...................................................................................... 186
xix

Figure A.60 DSC scan of polymer B7f. ...................................................................................... 186
Figure A.61 DSC scan of polymer B8f. ..................................................................................... 187
Figure A.62 DSC scan of polymer B9f. ...................................................................................... 187
Figure B.1
1
H-NMR (CDCl3, 25°C, 500 MHz) of P1. .............................................................. 202
Figure B.2
1
H-NMR (CDCl3, 25°C, 500 MHz) of P2. ............................................................... 203
Figure B.3
13
C-NMR (CDCl3, 25°C, 600 MHz) of P2. .............................................................. 203
Figure B.4
1
H-NMR (CDCl3, 25°C, 500 MHz) of P3. ............................................................... 206
Figure B.5
13
C-NMR (CDCl3, 25°C, 600 MHz) of P3. ............................................................. 207
Figure B.6
1
H-NMR (CDCl3, 25°C, 500 MHz) of P4. ............................................................... 207
Figure B.7
13
C-NMR (CDCl3, 25°C, 600 MHz) of P4. .............................................................. 208
Figure B.8
1
H-NMR (CDCl3, 25°C, 500 MHz) of P5. .............................................................. 208
Figure B.9
13
C-NMR (CDCl3, 25°C, 600 MHz) of P5. .............................................................. 209
Figure B.10
1
H-NMR (CDCl3, 25°C, 500 MHz) of Ti(O
i
Pr)4 catalyzed transesterification of
poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)
hexan-1-ol. .................................................................................................................................. 213
Figure B.11
1
H-NMR (CDCl3, 25°C, 500 MHz) of Ti(O
i
Pr)4 catalyzed transesterification of
poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)
hexan-1-ol with a reaction time of 7 days. ................................................................................. 214
xx

Figure B.12
1
H-NMR (CDCl3, 25°C, 500 MHz) of Ti(O
i
Pr)4 catalyzed transesterification of
poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)
hexan-1-ol with o-DCB as the solvent. ....................................................................................... 215
Figure B.13
1
H-NMR (CDCl3, 25°C, 500 MHz) of Ti(O
i
Pr)4 catalyzed transesterification of
poly(methyl acrylate) with 2-(9H-carbazol-9-yl)ethan-1-ol. ...................................................... 216
Figure B.14
1
H-NMR (CDCl3, 25°C, 500 MHz) of ZnTAC24 catalyzed transesterification
of poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)
hexan-1-ol. .................................................................................................................................. 217
Figure B.15
1
H-NMR (CDCl3, 25°C, 500 MHz) of ZnTAC24 catalyzed transesterification
of poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)
hexan-1-ol with increased catalyst loading and increased equivalents of the alcohol. ............... 218
Figure B.16
1
H-NMR (CDCl3, 25°C, 500 MHz) of ZnTAC24 catalyzed transesterification
of poly(methyl acrylate) with 2-(9H-carbazol-9-yl)ethan-1-ol. .................................................. 219
Figure B.17
1
H-NMR (CDCl3, 25°C, 500 MHz) of TBD catalyzed transesterification of
poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)
hexan-1-ol. ................................................................................................................................. 220
Figure B.18
1
H-NMR (CDCl3, 25°C, 500 MHz) of TBD catalyzed transesterification of
poly(methyl acrylate) with 2-(9H-carbazol-9-yl)ethan-1-ol. ...................................................... 221
xxi

Figure B.19
1
H-NMR (CDCl3, 25°C, 500 MHz) of DMPA catalyzed thiol-ene reaction of
poly(allyl methacrylate) with 2-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)
ethane-1-thiol. ............................................................................................................................. 223
Figure B.20
1
H-NMR (CDCl3, 25°C, 500 MHz) of DMPA catalyzed thiol-ene reaction of
poly(allyl methacrylate) with 2-(9H-carbazol-9-yl)ethane-1-thiol. ........................................... 224
Figure B.21
1
H-NMR (CDCl3, 25°C, 500 MHz) of Sc(OTf)3 catalyzed thiol-ene reaction of
poly(allyl methacrylate) with 9H-carbazolyl-ethane-1-thiol. ..................................................... 226
Figure B.22
1
H-NMR (CDCl3, 25°C, 500 MHz) of Sc(OTf)3 catalyzed thiol-ene reaction of
poly(allyl methacrylate) with 9H-carbazolyl-ethane-1-thiol with an increased reaction
temperature of 100 °C and an increased reaction time of 5 days. .............................................. 227
Figure B.23
1
H-NMR (CDCl3, 25°C, 500 MHz) of Sc(OTf)3 catalyzed thiol-ene reaction of
poly(allyl methacrylate) with 9H-carbazolyl-ethane-1-thiol with an increased reaction
temperature of 100 °C, an increased reaction time of 5 days and an increased catalyst
loading of 40 mol-%. ................................................................................................................. 228
Figure B.24 GPC trace of P1 with Mn = 35.72 kg/mol and Đ = 2.86. ........................................ 229
Figure B.25 GPC trace of P3 with Mn = 38.64 kg/mol and Đ = 5.46. ........................................ 229
Figure B.26 GPC trace of P4 Mn = 71.59 kg/mol and Đ = 3.43. ................................................ 230
Figure B.27 GPC trace of P5 Mn = 38.84 kg/mol and Đ = 2.08. ................................................ 230
Figure B.28 Differential scanning calorimeter trace of P3. ........................................................ 231
xxii

Figure B.29 Differential scanning calorimeter trace of P4. ....................................................... 231
Figure B.30 Differential scanning calorimeter trace of P5. ........................................................ 232
Figure B.31 UV/Vis-absorption spectra of as cast polymers. ..................................................... 232
Figure B.32 UV/Vis-absorption spectra of polymers after annealing at 150 °C for 30 min. ..... 233
Figure B.33 PL emission spectra of as cast polymers. ............................................................... 234
Figure B.34 PL emission spectra of polymers after annealing at 150 °C for 30 min. ................ 234
Figure B.35 Representative current-voltage plots for P3 as-cast (black), after annealing at
150 °C (red) and after annealing at 210 °C (blue). ..................................................................... 235
Figure B.36 Representative current-voltage plots for P4 as-cast (black), after annealing at
150 °C (red) and after annealing at 210 °C (blue). ..................................................................... 235
Figure B.37 Representative current-voltage plots for P5 as-cast (black), after annealing at
150 °C (red) and after annealing at 210 °C (blue). ..................................................................... 236
Figure C.1
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of atactic PAMA. ............................... 251
Figure C.2
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of isotactic PAMA. ............................. 252
Figure C.3
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of tBuCz-ata. ....................................... 253
Figure C.4
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of tBuCz-iso. ....................................... 256
Figure C.5
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of Cz-ata. ............................................ 256
xxiii

Figure C.6
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of Cz-iso. ............................................. 257
Figure C.7
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the solid filtrate of the thiol-ene
reaction of atactic PAMA with 2-(3,6-diphenyl-9H-carbazol-9-yl)ethane-1-thiol. .................... 259
Figure C.8
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the filtrate after the thiol-ene
reaction of atactic PAMA with 2-(3,6-diphenyl-9H-carbazol-9-yl)ethane-1-thiol. .................... 259
Figure C.9
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of 2-(3,6-diphenyl-9H-carbazol-9-
yl)ethane-1-thiol (top) and the dimerized 1,2-bis(2-(3,6-diphenyl-9H-carbazol-9-
yl)ethyl)disulfane (bottom). ........................................................................................................ 260
Figure C.10 H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed
in Table C.3, entry 1. .................................................................................................................. 262
Figure C.11
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed
in Table C.3, entry 2. ................................................................................................................. 263
Figure C.12
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed
in Table C.3, entry 3. .................................................................................................................. 264
Figure C.13
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed
in Table C.3, entry 4. .................................................................................................................. 263
xxiv

Figure C.14
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed
in Table C.3, entry 5. .................................................................................................................. 264
Figure C.15
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed
in Table C.3, entry 6. .................................................................................................................. 267
Figure C.16
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed
in Table C.3, entry 7. .................................................................................................................. 268
Figure C.17
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 9-(2-mercaptoethyl)-9H-carbazole-3,6-dicarbonitrile. .......................................... 269
Figure C.18 Differential scanning calorimeter trace of tBuCz-ata. ............................................ 270
Figure C.19 Differential scanning calorimeter trace of tBuCz-iso. .......................................... 270
Figure C.20 Differential scanning calorimeter trace of Cz-ata. ................................................. 271
Figure C.21 Differential scanning calorimeter trace of Cz-iso. .................................................. 271
Figure C.22 UV/Vis-absorption spectra of as cast polymers. ..................................................... 272
Figure C.23 UV/Vis-absorption spectra of polymers after annealing at 150 °C for 30 min. .... 272
Figure C.24 PL emission spectra of as cast polymers. ............................................................... 273
Figure C.25 PL emission spectra of polymers after annealing at 150 °C for 30 min. ................ 274
xxv

Figure C.26 Optimized structure for atactic tBuCz polymer with 40 repeat units. .................... 275
Figure C.27 Optimized structure for isotactic tBuCz polymer with 40 repeat units. ................. 275
Figure C.28 Optimized structure for atactic Cz polymer with 40 repeat units. Reprinted with
permission from Samal et al.
1
Copyright 2021 American Chemical Society. ............................ 276
Figure C.29 Optimized structure for iostactic Cz polymer with 40 repeat units. Reprinted
with permission from Samal et al.
1
Copyright 2021 American Chemical Society. .................... 276

xxvi

List of Schemes
Scheme 2.1 General synthesis of block copolymers PS-b-PAMA and their functionalization
with N-Carbazolylethanethioate to give PS-b-PCzETPMA. ........................................................ 98
Scheme 3.1 Synthesis of isotactic poly(propargyl methacrylate) poly(PgMA) P2 and its
functionalization with (substituted) azide-carbazoles to give polymers P3-P5. ......................... 116
Scheme 4.1 General synthesis of PAMA parent polymers and functionalization with
(substituted) N-carbazolylethanethioate to give poly((N-carbazolylethylthio)propyl
methacrylates) (PCzETPMAs). For R = H, tBu the initiator in the thiol-ene reaction was
DMPA, the solvent was toluene and the time was 24 hours. ...................................................... 133

xxvii

Abstract

By
Alexander Schmitt
Doctor of Philosophy in Chemistry

Over the last decades conjugated polymers (CPs) have gained increasing attention for the use
in various organic electronics such as organic photovoltaics (OPVs), organic field effect transistors
(OFETs), organic light emitting diodes (OLEDs), bioelectronics and electrochromics. The unique
advantages associated with these organic polymers such a light weight, high flexibility, low costs,
biocompatibility and the potential for easily scalable roll-to-roll processing make them a highly
attractive alternative to more traditionally used, inorganic materials in (opto-)electronic devices.
However, despite the significant advances made in the field of CPs which has resulted in a plethora
of intricately designed polymers yielding record breaking devices performances, they still suffer
from a number of critical limitations. CPs have significantly lower molecular weights and higher
dispersities compared to established non-conjugated polymers while also exhibiting low
environmental stability, very limited mechanical stability and low solubility. Additionally, the
need for compatibility of the polymerization methodologies with fully conjugated monomers
significantly restricts the suite of polymerization procedures available for the synthesis of CPs
which generally do not allow for the synthesis of more complex, hierarchically ordered polymer
structures or an efficient control over the polymer end groups.
xxviii

A novel class of materials with the potential of overcoming these challenges without sacrificing
the advantageous properties associated with CPs are non-conjugated electroactive pendant
polymers (NCPEPs). NCPEPs are polymers with a fully non-conjugated backbone to which
electroactive pendant groups are attached via spacers of fixed length and nature. Unlike CPs, they
are compatible with the methodologies for highly controlled polymerizations established for non-
conjugated polymers such as living radical, living ionic, ring opening or metallocene
polymerizations. Additionally, these methodologies also allow for the synthesis of more complex
electroactive polymer structures inlcuding block-copolymer, graft-polymers or star-shaped
polymers. Although due to significant disorder and only limited π–π stacking, charge carrier
mobilities of typical NCPEPs were orders of magnitude lower than in CPs, recent work in the field
has demonstrated that through understanding of fundamental structure–property relationships in
these NCPEP their structural parameters, most notably stereoregularity of the backbone and length
of the spacer, can effectively be tuned leading to significantly improved charge carrier mobilities
that even outperform certain well-established CPs.
In this dissertation such structure–property relationships are investigated for tuning of the
polymer architecture and the nature of the pendant group. The complexity of the architecture of a
NCPEP system was increased from homopolymers to block-copolymers and in separate NCPEP
homopolymers the structure of the pendant group was extended to disubstituted carbazoles bearing
conjugated thiophene and bulky alkyl substituents respectively. Along with the structural
parameter, the compatibility of extended pendant groups with established post-polymerization
methodologies is explored and new functionalization techniques are developed to synthesize
functionalized NCPEPs with high charge carrier mobilities.
xxix

In Chapter 1, an overview of the development of the field of NCPEPs is given with a focus
on the structure–property relationships that have been established for this class of materials to date.
Motivations for the research on NCPEP systems as well as synthetic routes towards various classes
of both stereoregular and stereorandom NCPEPs are discussed and the current state of the literature
on the effects of tuning of structural variables such as stereoregularity, lenghts and nature of
spacers, polymer architechture and the structre of the pendant group on the properties of the
respective polymers is summarized. This chapter provides the background for the reseach on the
novel structure–property relationships described in detail in Chapters 2-4.
In Chapter 2, the complexity of the polymer architecture of a previously reported poly((N-
carbazolylethylthio)propyl methacrylate) (PCzETPMA) NCPEP system was increased by
introduction of a second, electroinactive poly(styrene) (PS) block via anionic, living
polymerizations yielding a family of PS-b-PCzETPMA block copolymers as the first example of
NCPCP block copolymers with a controlled stereoregularity of the NCPEP-block. Across a family
of nine block copolymers molecular weights, tacticities of the PCzETPMA-blocks and the PS to
PCzETPMA block ratios were tuned. Through hole mobility measurements via the space charge
limited current (SCLC) technique, we found an increase in hole mobilities with higher molecular
weights, longer PCzETPMA-blocks, and higher degrees of isotacticity of the PCzETPMA-block.
This is the first report on block copolymers featuring an NCPEP-block of controlled tacticity and
demonstrates that complex polymer architectures can be realized with NCPEPs without sacrificing
control over their backbone stereoregularity and without significantly suppressing the hole
mobilities in the resulting copolymers.
In Chapter 3, tuning of the pendant group as a vital structural variable in stereoregular
NCPEPs is investigated for poly((carbazolyl-alkyl-triazolyl)methyl methacrylates
xxx

(PCzATMMAs) by expanding the size of the penadant group from carbazole to 3,6-bis(4-(2-
ethylhexyl)thiophen-2-yl)-carbazole. To facilitate the synthesis of a stereoregular NCPEP with this
extended pendant group a post-polymerization functionalization based on copper-catalyzed azide-
alkyne click chemistry is established after a screening of established functionalization
methodologies bases on transesterification and thiol-ene click chemistry found these
methodologies to be incompatible with the extended pendant group investigated here.
Additionally, spacer length effects are investigated for unsubstituted carbazole pendants for the
clicked, triazole containing spacers in the PCzATMMAs to allow for a comparison with spacer
length effects previously reported by our group for linear spacers in poly(N-carbazolylalkyl
acrylates). It was found that spacer length has an effect on this particular class of NCPEPs as well
with a six carbon spacer in between the triazole formed during the functionalization reaction and
the pendant group affording higher hole mobilities than the ananlogous polymer with a two carbon
spacer. Extending the size of the pendant group was found to also affect polymer properties with
bathochromic shifts observed in the absorption and emission spectra upon introduction of 3,6-
bis(4-(2-ethylhexyl)thiophen-2-yl)-carbazole and decreased hole mobilities compared to
unsubstituted carbazole as the pendant group. This is the first report on the introduction of the
extended pendant group 3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-carbazole into stereoregular
NCPEPs and describes the only post-polymerization functionalizaton method compatible with this
pendant group.
In Chapter 4, the application of the post-polymerization methodology for NCPEPs based on
photochemical thiol-ene click chemistry developed by our groups for functionalization with 3,6-
disubstituted carbazoles that would allow for a systematic study of the effects of substitution of
the pendant group in stereoregular and stereorandom PCzETPMAs was investigated.
xxxi

Functionalizations with alkyl (t-butyl), aryl (phenyl), electron donating (methoxy) and electron
withdrawing (nitrile) substituent were attempted but only 3,6-di(t-butyl)carbazolyl-ethanethiol
was found to be compatible with the established thiol-ene procedure despite optimization studies
for the reaction conditions for the remaining disubstituted carbazoles. The observed limitations of
the thiol-ene functionalization method were discussed and the effects of disubstitution with the
t-butyl-groups on the properties of the resulting polymers compared to polymers bearing
unsubstituted carbazole pendant group were demonstrated. Hole mobilities were found to decrease
by about an order of magnitude upon introduction of the bulky alkyl substituent with the decrease
being more significant in the isotactic PCzETPMAs. Reduced ordering of the polymer backbone
and consequently decreased π-overlap between the pendant groups in the t-butyl-polymers was
indicated by DFT modeling as a factor contributing to the observed lower hole mobilities. This is
the first report on systematic testing of the compatibility of the photochemical thiol-ene post-
polymerization functionalization methodology with differently substituted carbazole pendant
groups and reports for the first time the effects of substitution of the pendant group of a
stereoregular NCPEP with the bulky alkyl substituent t-butyl.
1

Chapter 1: Relating Structure to Properties in Non-Conjugated Pendant Electroactive
Polymers
1.1 Introduction
Since the development of the first extended conjugated systems, the field of π-conjugated
organic polymer has evolved into one of the most intensely studied areas in polymer chemistry
and material science with a plethora of already established applications and the potential to be a
key technology for the coming Internet of Things era. From early applications in corrosion
protection, organic dielectric layers, antistatic coatings and electromagnetic interference shielding,
continuous optimization efforts and increasingly better understanding of fundamental structure-
function relationships soon extended the areas in which these conjugated polymers were utilized
to organic-light emitting diodes (OLEDs), organic field effect transistors (OFETs), light harvesting
devices such as organic photovoltaics (OPVs) and organic solar cells (OSCs) and batteries.
1–14

Conjugated polymers have received considerable attention owing to their unique properties
compared to all other established, conductive materials for (opto-)electronic applications such as
substantially lighter weight, increased flexibility and biocompatibility, reduced toxicity and
compatibility with convenient, large-scale roll-to-roll processing.
15–19
It is also precisely these
properties that motivate current research of next generation conjugated polymeric organics as the
most promising materials for the emerging class of stretchable and wearable electronics with
certain materials possessing favorable biocompatibility and biodegradability that enable flexible
electronics to seamlessly interface with biological systems.
16,20,21
This seamless interface between
electronics and living tissue facilitated by the chemical nature of organic conjugated polymers that
are structurally much more similar to biological systems than any current inorganic material based
on metals or ceramics, as well as their structural tuneability that can allow for Young’s moduli
similar to those of soft tissue and their ion conductivity makes this new generation of organic
2

materials promising for use in bioelectronic medicine, photodynamic therapy and skin-mounted
health monitoring devices.
17,22
From a chemistry perspective, the broad range of current of
emerging applications of these materials makes continuous efforts for the development of novel
structures and optimization of their syntheses a pivotal task.
Within conjugated organic materials most chemical research efforts focus on the class of
conjugated polymers (CPs). These macromolecules with extended conjugated systems of
delocalized electrons that are capable of absorbing light of broad wavelength ranges act as
semiconductors that can readily conduct charge carriers due to their low band gaps.
23
The
significance of these unique materials was recognized with the Nobel Prize in 2000 being awarded
to Heeger, MacDiarmid and Shirakawa for their work on highly conductive iodine-doped
polyacetylenes in 1977.
24–26
Since these starting days the chemical structures of CPs have become
significantly more sophisticated and have branched off into distinct designs for the various classes
of applications with some representative structures shown in Figure 1.1. Despite this continuously
increasing library of polymers with increasingly more intricate structures, the polymerization
methodologies for synthesizing these polymers have changed very little over the last decades. The
most common methodologies rely on transition metal catalyzed polycondensations between aryl
halide functionalized monomers and monomers functionalized with organometallic groups
including organoboron (Suzuki-Miyaura polycondensation), organozinc (Negishi
polycondensation), organotin (Stille-Migita polycondensation) or organomagnesium functional
groups (Kumada polycondensation).
27–30
More recently organometallic functionalized monomers
have been replaced with monomers bearing activated C-H bonds in Direct Arylation
Polymerizations (DArP) to streamline the synthesis, allow for higher atom economy and to avoid
the formation of environmentally harmful side products.
31–34
While there is a limited number of
3

methodologies that follow a more controlled chain-growth mechanism, most notably Kumada- and
Suzuki-Transfer Polymerizations which are limited by the scope of compatible monomers and the
low molecular weight of the CPs made from them, the vast majority follows a step-growth
mechanism that does not allow for efficient end-group control or the synthesis of complex
structures such as block copolymers.
35-39

Figure 1.1 Exemplary structures of CPs used as the active material in various organic electronic
applications.

Despite the major progress made in the field of CPs and the significant advantages associated
with them compared to their inorganic counterparts, there are a number of challenges remaining.
One being the elaborate synthesis especially of CPs used in high efficiency devices with certain
polymers requiring over 15 steps to synthesize which results in cost ineffective materials that are
not viable for large scale manufacturing.
40–42
Additionally, whenever established organometallic
monomer based polymerization methods are used, stochiometric amount of oftentimes toxic
byproducts are generated.
43
Even with more environmentally friendly alternatives such as DArP
4

the resulting polymers give significantly lower molecular weights and higher dispersities (Ð) than
more traditional non-conjugated polymers and in the vast majority of cases they do not allow for
an efficient control over the polymer endgroup.
44

Most CPs show poor environmental stability with rapid oxidation of π-conjugated moieties
especially under exposure to air, and very limited mechanical properties with low stretchability
due to their rigid structure.
15,45,46
However, the most fundamental limitation is the need for
compatibility of the polymerization conditions with fully conjugated monomers which in most
cases does not allow for the use of well-established methods such as living ionic, radical or
metallocene polymerizations.
47–49
While there have been successful efforts in synthesizing
conjugated block copolymers by step growth and even living polymerization methods, these
methods still suffer from a very limited monomer scope and low molecular weights and their
workup oftentimes includes extensive block-purification that is highly impractical especially for
larger scale applications.
50–54
Consequently, the polymerization methods for non-conjugated
polymers not only produce much higher molecular weights at lower Ð, more importantly they also
allow for precise structural control that facilitates the synthesis of advanced architectures such as
block-copolymers, graft polymers and star-shaped polymers that are capable of hierarchical
organization.
An emerging class of polymers looking to address these limitations are non-conjugated
pendant electroactive polymers (NCPEPs). NCPEPs are polymers with a fully non-conjugated
backbone to which electroactive pendant groups are attached via spacers of fixed length and nature.
They offer the possibility of utilizing the advantages associated with non-conjugated polymers, in
particular their broader and more well-established chemistry and superior mechanical properties
and stability compared to CPs, with the potential of simultaneously maintaining the desirable
5

optical and electronic properties of CPs. Despite a growing number of both fundamental and
application-based studies concerned with NCPEPs, an overview of the current state of research on
these promising materials has not been attempted. Specifically, a systematic summary of the
established structure-function relationships in NCPEPs that can serve as a guideline for the
conscious development of future polymers is lacking in literature to date. With this review we aim
to provide such an overview by focusing on studies that demonstrate clear structure-function
relationships for NCPEPs that can aid in the structural design in the future.
Before diving into in-depth studies on NCPEP structure-function relationships, it is critical to
first understand the general structure and synthetic methodologies towards making this unique
class of polymers. As depicted in Figure 1.2, the general characteristics of NCPEPs are (a) the
structure of their backbone, which refers to the non-conjugated monomeric unit(s) forming the
backbone as well as the general make-up of the backbone whether it is a homopolymer, a random
copolymer, a block-copolymer or another more complex structure of higher order, (b) the
stereochemistry (tacticity) of the repeat units in the polymer to which a spacer is attached, (c) the
length and chemical structure of the spacer and (d) the structure of the pendant group including
the size of conjugated systems contained in that group and potential solubilizing substituents that
are attached. All of these variables have a profound effect on key properties of the resulting
polymers such as their morphology through packing of the polymer chains and on charge carrier
mobilities through overlap of the pendant groups. Studies detailing the effects of each variable are
discussed in the following paragraphs.

6

Figure 1.2 General schematic structure of NCPEPs.

The difference in the synthesis of NCPEPs compared to CPs is another aspect that is critical to
highlight prior to detailed discussions of any structure-function relationships. As depicted in
Figure 1.3a, there are two general approaches to synthesize NCPEPs: (a) functionalization of the
respective monomer with the pendant group followed by polymerization to give the final non-
conjugated polymer and (b) polymerization of unfunctionalized monomers to give a non-
conjugated polymer backbone to which pendant groups are then attached via post-polymerization
functionalization. While the chemistry of the polymerization itself does not significantly differ
between both approaches, the main difference is that for approach (a) the entire pedant group must
be chemically stable under the polymerization conditions and potential side reaction on or with the
pendant group have to be considered. The suite of polymerization methodologies available for the
synthesis of NCPEPs and CPs however differ significantly regardless of which approach is
employed. As previously mentioned, the synthesis of CPs is limited to organometallics based- and
direct arylation polymerization and catalyst transfer polymerization in the case of living
polymerizations due to the need for compatibility with the fully conjugated monomers,
27–31
while
7

a much broader range of polymerization methodologies are established for the more widely used
non-conjugated monomers such as living ionic, radical, ring-opening, Ziegler-Natta or
metallocene polymerizations.
47-49,55

Figure 1.3 a) Exemplary synthesis schemes for functionalization of NCPEPs by
transesterification via the two general synthetic routes: (1) polymerization of fully functionalized
monomers and (1) polymerization of the backbone followed by a post-polymerization with the
respective pendant group. b) Advanced NCPEP architectures shown schematically for a NCPEP with
a simple polyvinyl backbone and a carbazole pendant group (blue).
8

Besides the typically higher molecular weight and lower Ð, they allow for efficient control of
the polymer end-group which has been a long-standing challenge in CP synthesis. While there
have been advances in developing more controlled CP polymerization methodologies, namely
Kumada and Suzuki Catalyst-Transfer Polymerizations, they still suffer from drawbacks such as
very limited monomer scope, low molecular weight and high Ð.
35,36
Additionally, unlike the
polymerization methodologies used for CPs which are largely limited to homopolymers,
alternating- and random copolymers and in the case of few selected monomers gradient
copolymers as demonstrated by McNeil et al., the methodologies compatible with NCPEPs allow
for the synthesis of advanced architectures such as block copolymers, graft and star polymers,
schematically depicted in Figure 1.3b.
56–58
This is especially relevant in the context of organic
electronics in which charge carrier mobilities are known to be closely related to the morphology
of the active material being used. Having locked-in hierarchical structures such as lamellar
stackings of block-copolymers can circumvent issues such as migration and aggregation that are
known to negatively impact the morphology of CPs and mixtures thereof over time.
59–62
NCPEPs
are an alternative class with which such hierarchical structures can be realized without
compromising the electroactive properties of CPs, making them a promising target for organic
electronics.
Historically, some of the first examples of polymer systems bearing conjugated and
electroactive pendant groups were in the field of liquid crystalline materials: side-chain liquid
crystal polymers (SCLCPs).
63
While design of SCLCPs was not necessarily focused on the same
properties that are relevant for NCPEPs in the context of applications in organic electronics such
as charge carrier mobilities, they did show a strong influence of the same structural features
previously discussed for NCPEPs, nature of the spacer and the pendant group and stereochemistry
9

of the monomeric unit in the backbone, on the properties of the respective polymers.
64
These early
systems laid the groundwork of translating the polymerization methods of traditional non-
conjugated systems to both monomer swith optically and/or electronically active pendant groups
and monomers with specifically designed functionalization sites where these pendant group could
be introduced post polymerization. With these adapted methodologies even more complex ordered
polymer structures such as di- and tri-block copolymers, for which no broadly applicable synthetic
methodology exists in the case of CPs, could be realized. Characterization of these higher ordered
pendant polymers revealed a number of unique properties especially regarding their morphology,
with some exemplary studies discussed in the following, that played a pivotal role in their transition
into the field of organic electronics.
For example, it had been shown that mesogenic side groups of highly stereoregular polymers
are positioned more favorably for crystallization compared to their stereorandom analogues.
64
In
block-copolymers with a polystyrene-block a significant influence of the block ratio on the domain
ordering was found with certain ratios leading to a distinct lamellar phase arrangement.
65
Other
block-copolymers were found to separate on the microphase into the classic morphologies known
for coil-coil block-copolymers.
47,63
Such ordered morphologies on the microscale are on the same
length scale as exciton diffusion lengths in organic light harvesting devices and therefore highly
desirable for the potential of efficient charge separation and transport.
66
Furthermore, achieving
these microphase separated morphologies with higher order polymers such as block-copolymers
is expected to increase the overall stability of the active layer in the respective devices over longer
periods of time compared to what can be achieved with CPs and CP-containing mixtures today.
In this review the NCPEPs are classified bases on the general structure of their backbone.
Table 1.1 summarizes the general monomers and their corresponding polymer structures that are
10

considered for this classification. For each general backbone structure relevant studies on
structure-function relationships of the respective class of NCPEPs will be discussed in a separate
section.
Table 1.1 General monomer structures and their corresponding polymer structures that make
up the backbone of the respective NCPEPs.
General monomer structures Corresponding general polymer structures

vinyl

poly(vinyl)

styrene

poly(styrene)

acrylate

poly(acrylate)

methacrylate

poly(methacrylate)

norbornene

poly(norbornene)

We note that this review is not intended as a comprehensive summary of all NCPEP polymer
systems reported in literature. Instead, we want to highlight selected studies demonstrating clear
11

structure-property relationships for this class of polymers that can serve as guidelines for the
rational design of novel NCPEPs in the future. Additionally, we have purposely limited the scope
to non-crosslinked polymers with fully non-conjugated backbones. While there has been extensive
research on various hybrid systems such as block-copolymers in which a conjugated block is
linked to a NCPEP block, NCPEP with cross-linked pendant groups to increase the size of the
conjugated system and polymer with fully conjugated backbones that feature additional
electroactive pendant groups on their side chains, including these systems would go beyond the
scope of this review.
67-70

1.2 Structure-property relationships in NCPEPs
1.2.1 Poly(vinyl) NCPEPs
1.2.1.1 Homopolymers of poly(vinyl) NCPEPs
Vinyl based polymers, specifically poly(vinyl carbazole) (PVK) depicted in Figure 1.4a, are
amongst the first reported NCPEPs. Since the discovery of the photoconductive properties of PVK
by Hoegl et al. in 1957, poly(vinyl) polymers have been intensely studied in regards to their charge
transport properties, for instance as hole transport layers for OLEDs or photorefractive devices.
71,72

Commercially available atactic PVK has charge carrier mobilities in the range of 10
-6
– 10
-9

cm
2
/V∙s, as reported by Maglione et al. amongst other who found an average hole mobility of μh
= 4.8 × 10
-9
cm
2
/V∙s from field effect measurements on ITO/PVK/Al single layer devices.
72-74
In 2019 Fujii et al. investigated the effect of stereoregularity on the hole mobility of PVK.
75
A
CF3SO3H, n-Bu4NCl and ZnCl2 initiation system was used to synthesize highly isotactic PVK
(Figure 1.4a) in a living, cationic polymerization which gave a family of four polymers with triad
tacticities ranging from mm = 50% to mm = 94%. Through the charge extraction by linearly
12

increasing voltage (CELIV) technique a clear increase in hole mobility with an increasing degree
of stereoregularity was demonstrated with the most isotactic PVK (mm = 94%) exhibiting a
mobility of μh = 2.03 × 10
-6
cm
2
/V∙s, 2.3 times the value of the stereorandom PVK (mm = 50%).
The effect was even more pronounced after annealing of the polymers at 220 °C for 10 min which
resulted in μh = 4.02 × 10
-6
cm
2
/V∙s for the most isotactic PVK, 4.8 times the value of the
stereorandom PVK. This effect was reasoned to stem from the formation of more ordered,
crystalline domains as observed for annealed PVK in literature which are more favored in isotactic
PVK due to the pendant groups already exhibiting a higher degree of ordering along the polymer
backbone.
76,77
The annealing process was argued to promote ordering of the carbazole groups
through induced heating stress leading to formation of relatively long carrier transport channels
which suppress trapping sites resulting in enhanced hole mobilities.
Cationic polymerization for the synthesis of highly isotactic PVK (94% mm) was also
employed by Leibfarth et al. who recently reported optically active helices of this PVK as the first
example of a stereoselective, cationic, helix-sense selective polymerization of a prochiral vinyl
monomer. Chiral bis(oxazoline)-scandium Lewis acids were used as the catalytic system that allow
control not just the tacticity but also the main-chain atropoisomeric conformation resulting in
helix-sense-selective PVKs. Polymer helicity was found to strongly depend on the stereoselectivity
of the first monomer propagation, whereas tacticity was more heavily depend on the
thermodynamically controlled conformation of the growing polymer chain end.
78
This is one of
the very few polymer systems, and the only one based on a prochiral vinyl monomer, for which
helicity and tacticity can be controlled independently.
Stereoregularity effects were also investigated for poly(N-pentenyl-carbazoles) (PPKs) by
Minarini et al. who reported on the physical-chemical properties of isotactic and syndiotactic PPK
13

shown in Figure 1.4a.
79
Both stereoregular polymers were synthesized by Ziegler-Natta
polymerization in toluene with rac-dimethylsilylbis(1-indenyl)zirconium dichloride and
diphenylmethylidene(cyclopentadienyl)-(9-fluorenyl)zirconium dichloride as the respective
catalytic precursors mixed with methylaluminiumoxane (MAO) giving molecular weights of 2.20-
2.39 kg/mol and Ð < 1.20 for the acetone-soluble fractions.
Analysis by X-ray revealed a semicrystalline morphology for iso-PPK while syn-PPK was
found to be amorphous. Photoluminescence (PL) emission spectra shown in Figure 1.4b exhibited
overlapping fluorescence bands for excimers formed by partial overlap of the carbazole groups at
396 nm and full overlap at 420 nm. While these peaks can be observed in both polymers, the
intensities for syn-PPK are significantly reduced compared to iso-PPK particularly for the peak at
420 nm indicating a strong influence of polymer tacticity on the emission intensities and thus on
excimer formation. The pendant groups in iso-PPK are better positioned for partially overlapping
and more significantly for fully overlapping arrangements leading to increased formation of the
respective excimers. In their fluorescence spectra both PPK polymers showed monomer emission
corresponding to individual carbazole groups which cannot be observed for PVK demonstrating
an additional effect of the presence of the flexible propyl-spacer on the optical properties of the
polymers unrelated to tacticity. Finally, both polymers were tested as emissive layers in OLEDs
with mono- and multilayer structures, which gave current efficiencies in the same order of
magnitude as PVK-based OLEDs, ~0.1 cd/A at 22V, which was attributed to a low conductivity
of the single emissive layer and the asymmetry of electron and hole currents. Electroluminescence
(EL) spectra of the devices confirmed strong influences of tacticity with iso-PPK showing a greater
contribution of the partially overlapping excimer than syn-PPK. Specifically in the multilayer
14

devices this is evidenced by significantly reduced peak intensities in EL for the emission bands at
513 nm and 615 nm when switching from iso-PPK to syn-PPK.

Figure 1.4 a) Chemical structure of poly(vinyl) derived NCPEP homopolymers. b) PL spectra of
iso-PPK and syn-PPK films under an excitation wavelength of 298 nm. Reprinted with permission
from Liguori et al.
79
Copyright 2017 IOP Publishing.
15

In 2018 Praglio et al. studied the influence of tacticity on excimer formation for the identical
iso- and syn-PPK polymers through fluorescence measurements as part of a larger family of
polymers also including isotactic poly(N-butenyl-carbazole) (PBK) and isotactic and syndiotactic
poly(N-hexenyl-carbazole) (PHK) depicted in Figure 1.4a.
80
Similarly, the polymers were made
via Ziegler-Natta polymerization with rac-dimethylsilylbis(1-indenyl)zirconium dichloride/MAO
and diphenylmethylidene(cyclopenta-dienyl)-(9-fluorenyl)zirconium dichloride/MAO as the
respective catalytic systems yielding molecular weights of 3.00-5.60 kg/mol with dispersities of
1.25-1.60.
Morphological characterizations by DSC and WAXD showed crystalline structures for all
isotactic polymers and amorphous structures for all syndiotactic ones. In agreement with the
previously discussed study, in PL emission spectra bands at 396 nm corresponding to excimer
formation from partially overlapping carbazole groups and at 420 nm from full overlap were
reported. As observed by Minarini et al., the band at 420 nm is distinctly more intense in the
isotactic polymers suggesting a more favorable orientation of the pendant groups for π-π overlap.
79

For iso-PPK and syn-PPK the study supports these experimental findings with molecular dynamics
calculations that emphasize a strong influence of tacticity on relative emission intensities of the
two possible excimers stemming from partially and fully overlapping neighboring carbazoles.
Rather than focusing on tacticity effects, Wang et al. restricted themselves to atactic backbones
in a 2021 study that investigated the effect of varying the pendant group itself on the electronic
properties, in particular bandgaps, frontier orbital energies and hole transporting abilities, of the
resulting polymers by 3,6-disubstitution of commercially available PVK.
81
A bis-tBu-pyrenyl and
a bis-pyrenyl-thiophenyl derivative of PVK, poly(bis-tBu-pyrenyl-VK) and poly(bis-pyrenyl-
thiophenyl-VK), shown in Figure 1.4a, were synthesized.
16

The substituted polymers were designed with the objective to maximize intermolecular π-
contacts via more elongated π-ring systems to allow for effective π-π
*
electronic transitions. PVK
was brominated with NBS followed by a Suzuki-coupling with tBu-pyrene to yield poly(bis-tBu-
pyrenyl-VK). Stille-coupling of the brominated PVK with stannylated thiophene followed by a
second NBS bromination step and finally a Suzuki-coupling with pyrene yielded poly(bis-pyrenyl-
thiophenyl-VK). Charge carrier transport abilities for all three polymers were tested by coating
them as hole transport layers (HTL) in perovskite solar cells with the general structure
ITO/HTL/PEDOT:PSS/MAPbI3/PC70BM/TiOx/Al. Devices with PVK as the HTL had fill factor
(FF) values of 61 that were very similar to the control devices without a dedicated HTL but at an
increased internal resistance leading to slightly lower PCEs of 12.11%. Poly(bis-tBu-pyrenyl-VK)
devices showed slightly increased FF values but due to significantly decreased J SC owing to
adverse π-π interactions with the tBu-groups these devices gave the lowest PCEs. Poly(bis-
pyrenyl-thiophenyl-VK) devices on the other hand showed improved π-π stacking interactions
which led to improved current densities and FF values by more than 8% giving an average FF of
70 and consequently higher PCEs of 14.56%, an increase by more than 11%. Additionally, PVK
and poly(bis-pyrenyl-thiophenyl-VK) were tested as HTL in OPV devices of the general structure
ITO/HTL/PEDOT:PSS/PTB7-th:IEICO-4F/TiOx/Al. Improved current densities and FF value, 63
compared to 59 for the control device, and consequently higher PCEs of 10.06% and 10.76%
compared to 9.47% for the control device, were observed with poly(bis-pyrenyl-thiophenyl-VK)
and PVK respectively as the HTL with the former being the best performing device. Morphological
and optoelectronic characterization of poly(bis-pyrenyl-thiophenyl-VK) layers showed reduced
surface roughness compared to PEDOT:PSS films and the successful formation of a passivation
layer between ITO and PEDOT:PSS that suppresses leakage current and is indicative of an
effective intramolecular π-π self-assembly of the pyrene functional groups unlike what could be
17

observed with poly(bis-tBu-pyrenyl-VK) for which the bulkier tBu-groups likely are hindering the
intermolecular self-assembly. Finally, SCLC hole mobility measurements in HTL/PEDOT:PSS
devices demonstrated a clear impact of the nature of the pendant group, particularly the size of the
π-conjugated system, on resulting mobilities with poly(bis-pyrenyl-thiophenyl-VK) as HTL giving
μh = 5.13 × 10
-4
cm
2
/V∙s which outperformed PVK as HTL with μh = 2.02 × 10
-5
cm
2
/V∙s by more
than an order of magnitude. This study is a noteworthy example for the significant impact changes
in the chemical structure of the pendant group have on the resulting polymer properties especially
in device applications that considers both introduction of more extended conjugated system and of
sterically bulky groups into the pendant group.

1.2.1.2 Copolymers of poly(vinyl) NCPEPs
The previously discussed findings by Fujii et al. for stereoregular PVK homopolymers gave
the experimental evidence for predictions made in an earlier study by Mattice et al. based on
molecular dynamics simulations on trichromophoric vinylcarbazole-methyl methacrylate (VCz-
MMA) co-oligomers with increasing lengths of the MMA-blocks (Figure 1.5).
82
Isotactic meso-
CzP and syndiotactic racemo-CzP trichromophores were compared in regards to their modelled
intramolecular excimer formation. Rearrangement of meso-CzP led to significantly more
conformations with partial and complete overlap of the carbazole groups capable of forming
excimers than in racemo-CzP demonstrating a clear influence of tacticity on the positioning of
neighboring pedant groups and the resulting interactions between these pendants this positioning
allows for.
The importance of spatial proximity of the carbazole groups for intermolecular interactions
such as excimer formation was further demonstrated by increasing the size of the MMA-blocks in
18

between the pendants causing a sharp decline in excimer formation. These results were echoed by
experimental steady state fluorescence measurements on atactic VCz-MMA copolymers made
from AIBN-initiated radical polymerization with varying monomer ratios. Excimer emission
intensity was found to decrease with a decreasing ratio of VCz.
Similarly, Dais et al. found through energy calculations of isotactic, syndiotactic and atactic
PVK-trimers that only the isotactic trimer adopted proper parallel orientation of the carbazole
groups allowing for the formation of true excimers while in the syndiotactic and to a significantly
lesser degree in the atactic trimer only partial overlap of the carbazole groups was observed.
83

Tazuke et al. turned their focus on poly(vinyl) derived statistical copolymers instead of defined
block sequences and studied hole drift mobilities of the carbazole-derived extended pendant
groups 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane (VDCZB) and 9-ethyl-9H-carbazole (3VK) in
PVDCZB-co-P3VKs (Figure 1.5) and in the respective homopolymers (Figure 1.4) relative to
PVK.
84
The respective homopolymers and copolymers made from AIBN-initiated radical
polymerization, which gave molecular weights of 20 to 39 kg/mol. As indicated in Figure 1.5, the
ratio of vinyl-trans-di(carbazolyl)cyclobutane (VDCZB) in the copolymers was varied from 9%
to 67%.
19

Figure 1.5 Chemical structures of poly(vinyl) based NCPEP copolymers and of PDBF
copolymers.

Hole drift mobilities were determined from the time-of-flight (TOF) method and varied
significantly across the family of polymers despite carbazole acting as the hole-transporting moiety
for all of them. PVDCZB gave a mobility of μh = 3.20 × 10
-6
cm
2
/V∙s, 16 times higher than the
mobility for PVK. Both copolymers showed roughly twice the mobility of PVK while P3VK gave
the lowest mobility of μh = 1.90 × 10
-7
cm
2
/V∙s. Absorption spectra for DCZB-containing polymers
were mostly identical to those of PVK and P3VK, however the DCZB-containing polymers
showed a distinct lack of fluorescence emission from excimers generated by partially overlapping
carbazole groups that was present in PVK and P3VK. The excimers responsible for this emission
were reasoned to act as carrier trap sites also referred to as excimer-forming sites (EFS) and
consequently the lack of such trapping sites in PVDCZB and its copolymers was believed to be
the reason for the superior mobilities in these polymers. In regards to the role of the nature of the
20

pendant group the study was able to demonstrate a clear effect of the structure of the pendant on
the properties of the resulting polymers despite keeping the moiety for hole-transport constant.
In the context of this chapter we wanted to highlight a class of NCPEPs that does not fall into
the category of poly(vinyl) polymers but that are structurally closely related:
poly(dibenzofulvenes) (PDBFs). They can be conveniently synthesized via cationic, radical and
anionic polymerizations and it has been demonstrated that the pendant DBF moieties assume
structural conformations that allow for significant π-stacking. This leads to high charge carrier
mobilities in the range of 10
-4
cm
2
/V∙s as reported by Nakano et al., however at typically low
molecular weights in the range of 1-2 kg/mol due to the limited solubility of the polymers in
common organic solvents.
85

In a 2018 study, Nakano et al. investigated the effects of introducing electroinactive co-
monomers into PDFB via AIBN initiated radical polymerizations in toluene of DBF with (methyl
methacrylate) MMA, (2-hydroxyethyl methacrylate) HEMA, (methyl acrylate) MA and (2-
hydroxyethyl acrylate) HEA respectively.
86
Molecular weights for the copolymers depicted in
Figure 1.5 were 1.2-2.8 kg/mol with Ð < 1.60 and DBF ratios of 4% to 27%.
In PL spectra of the copolymers a sharp band in the range of 300-330 nm corresponding to
emission from isolated fluorene units and a broad band around 400 nm corresponding to excimer
emission from π-stacked dimers were observed. Determination of the ratios of π-stacked and
unstacked fluorene moieties from these peaks revealed that a higher DFB ratio in the polymer led
to more π-stacked units regardless of the nature of the electroinactive comonomer. In their DSC
profiles, the copolymers with MMA, MA and HEA exhibited clear glass transitions that were at
higher temperatures that the Tg of the respective homopolymers while PDBB-co-PHMEA did not
show a Tg unlike the homopolymer indicating that the presence of DBF affects the thermal
21

properties which was explained by π-stacked DBF sequences in addition to inter-chain hydrogen
bonding. Despite maintaining significant degrees of π-stacking, it was found trough comparison
with PDBF homopolymers made from radical and anionic polymerization that the less effective
stereocontrol in radical polymerizations leads to decreased π-stacking in PDBF and the random
copolymers. Importantly, this report is the first example of an attempt to modify properties of
PDBF to overcome critical limitations such as the previously mentioned low solubility by an
method that does not require modification of the structure of DBF itself but instead relies on the
copolymerization with other monomers.
The results from PL for these statistical copolymers are supported by an earlier report by
Nakano et al. on PMMA-b-PDBF block copolymers shown in Figure 1.5 made via living, anionic
polymerization which yielded polymer aggregates that exclusively showed excimer emission from
π-stacked dimers in their PL spectra despite introduction of an electroinactive block.
87
In fact, the
observed aggregate formations itself was attributed to extensive interchain π-stacking between the
PDBF-block of adjacent polymer chains.

1.2.2 Poly(styrene) NCPEPs
1.2.2.1 Homopolymers of poly(styrene) NCPEPs

Despite containing benzene as a conjugated pendant system, neat polystyrene exhibits low
charge carrier mobilities that do not render it an electroactive polymer itself.
88
It does however
provide a convenient scaffold for substitution towards more extended pendant groups and a
number of structural variables have been studied on poly(styrene) derived NCPEPs.
22

One example is a study by Xu et al. that compared the hole transporting properties of a
polystyrene derived polymer bearing methoxytriphenylamine-conjgated thiophene moieties with
the functionalized monomer and a small molecule model compound without the styrene moiety by
implementing them as the hole transport material (HTM) in FTO/c-TiO2/m-
TiO2/Cs0.05FA0.81MA0.14PbI2.55Br0.45/HTL perovskite solar cells.
89
The stereorandom polymer,
poly((4-Bz-Th)bis(4-MPh)An), was synthesized via AIBN-initiated radical polymerization in
THF over 72 hours yielding a molecular weight of 1.14 kg/mol and Ð = 1.60 and is depicted in
Figure 1.6a.
In their UV-Vis absorption spectra poly((4-Bz-Th)bis(4-MPh)An) and the respective monomer
(4-Bz-Th)bis(4-MPh)An showed the same absorption maxima at 384 nm, which was blue-shifted
by 16 nm due to a reduced electron density upon the introduction of the p-tolylmethoxyl group
compared to the model compound (Th)bis(4-MPh)An lacking such a group as a substituent. In PL
spectra the emission spectra of the polymer at 477 nm and of the monomer at 476 nm are red-
shifted compared to the model compound at 474 nm. The HOMO and LUMO energy levels as
determined from the redox behavior in cyclic voltammetry (CV) were similar across all three
compounds, with the polymer having a slightly deeper HOMO at -4.96 eV. Hole mobilities as
determined from SCLC in ITO/PEDOT:PSS/HTL/Au devices revealed the highest mobility for
the polymer with μh = 1.60 × 10
-4
cm
2
/V∙s while both small molecule compounds gave mobilities
that were an order of magnitude lower. These results were attributed to close stacking of the
conjugated moieties induced by the polymer backbone considering that an additional p-
tolylmethoxyl group by itself only marginally affected μh as seen for the two small molecule
compounds. In perovskite solar cell devices, the polymer as the HTM outperformed both small
molecule compounds in all metrics, VOC, JSC, FF and the overall PCE which was 16.8% compared
23

to 9.1% for the monomer and 2.4% for the model compound. Considering that a similar surface
roughness was measured for the polymer as for the monomer, the superior efficiency of the
polymer device was explained by its higher μh and lower HOMO level. Additionally, stability
testing in air over 30 days showed significantly improved stability of the polymer containing
device which maintained 80% of its efficiency.
In 2019 the same group investigated positional effects of triphenylamine-substituents on
carbazoles as pedant groups in atactic polystyrene-derived polymers.
90
As depicted in Figure 1.6a,
both 2,7- and 3,6-disubstituted carbazoles were synthesized and polymerized via AIBN-initiated
radical polymerization yielding poly(2,7-bis(MePh)An-Cz-styrene) and poly(3,6-bis(MePh)An-
Cz-styrene) respectively with molecular weights of 0.94-1.28 kg/mol and Ð = 1.46-2.02.
In UV/Vis absorption spectra, the 2,7-isomer showed a weak absorption peak at 291 nm and a
stronger peak at 291 nm while the 3,6-isomer showed a weak shoulder at 310 nm and a stronger
peak at 333 nm as depicted in Figure 1.6b. The bathochromic shift of the 2,7-isomer was explained
by a more effective and prolonged conjugation length of the triphenylamine moieties. In PL spectra
the emission maximum of the 2,7-isomer was at 453 nm while the maximum of the 3,6-isomer
was at 424 nm. The HOMO energy levels determined from CV were almost identical while the
LUMO of the 2,7-isomer was 0.27 eV lower. Hole mobilities were measured via the SCLC
technique in hole-only ITO/PEDOT:PSS/polymer/Au devices and gave similar μh of 1.12 × 10
-4

cm
2
/V∙s for the 2,7-isomer and 1.32 × 10
-4
cm
2
/V∙s for the 3,6-isomer. The superior μh in the 3,6-
isomer was explained by the formation of stable dictaions and trications upon receiving positive
charges due to the delocalization of charges throughout the conjugated system. In the 2,7-isomer
however, only dications were formed. Despite almost identical surface roughness, FF values for
ITO/SnO2/Cs0.05FA0.81MA0.14PbI2.55Br0.45/HTL/Au perovskite solar cell devices were higher with
24

the 3,6-isomer as the HTL: 73 compared to 68 for the 2,7-isomer. Short-circuit currents in the 3,6-
isomer were slightly superior as well, consequently giving higher device efficiencies of up to
18.45% demonstrating noticeable effects of the structure of a polymer pendant group in NCPEPS
on device performances even between structural isomers.
Substituent effects in atactic poly(vinyltriphenylamines) made via NMRP were also the focus
of a 2010 study by Thelakkat et al. alongside additional investigations into molecular weight
effects.
91
Dimethoxy-substituted triphenylamine was compared to unsubstituted triphenylamine
and an unsymmetric dimethoxytriphenyldiamine as pendant groups for styrene-derived NCPEPs
in applications for OFETs.
92
The three polymers shown in Figure 1.6a, PvTPA, PvDMTPA and
PvDMTPD, with molecular weights between 15.8 and 23.6 kg/mol displayed fully amorphous
morphologies and glass transition temperatures Tg from 130 to 175 °C in thermal characterizations.
In CV measurements PvTPA exhibited a HOMO energy level of 5.24 eV while for both
PvDMTPA and PvDMTPD the respective energy level decreased to 4.96 eV.
All polymers were tested in bottom gate bottom contact geometry OFET devices and charge
carrier mobilities were extracted from the saturation region of the transfer characteristics. Device
performances were tested as-cast and after annealing at around 15 °C above the Tg of the respective
polymer. Annealing led to a greater than tenfold increase in the drain current of PvTPA, a charge
carrier mobility of μ = 3.00 × 10
-5
cm
2
/V∙s and a threshold voltage of -37 V. Both as-cast
PvDMTPA and PvDMTPD showed significantly better performance with low threshold voltages
of -4 and -5 V respectively which shifted to -12 and -13 V upon annealing. Annealed PvDMTPD
yielded the best performing device with μ = 1.00 × 10
-4
cm
2
/V∙s and an on-off ratio of 2.3 × 10
3
.
PvTPA showed the highest contact resistance which was attributed lack of methoxy groups whose
spatial ordering at the dielectric interface was believed to cause the difference in contact resistance.
25

Figure 1.6 a) Chemical structures of poly(styrene) derived NCPEP homopolymers. b) Normalized
absorption and emission spectra of poly(2,7-bis(MePh)An-Cz-styrene) (black) and poly(3,6-
bis(MePh)An-Cz-styrene) (red). Reprinted with permission from Wu et al.
90
Copyright 2019
American Chemical Society.
26

Performance increases upon annealing in PvTPA were reasoned to stem from better packing
of the unsubstituted triphenylamine moieties whereas the bulkier nature of the pendant groups in
PvDMTPA and PvDMTPD did not allow for the same level or reorganization resulting in the more
minor changes after annealing. Finally, a family of PvDMPTAs with molecular weights from 3.0
to 30.0 kg/mol and Ð ≤ 1.20 was synthesized and their charge carrier mobilities were measured.
Charge carrier mobilities were constant around 10
-5
cm
2
/V∙s regardless of the molecular weight of
the polymer while physical properties such as Tg scaled with the molecular weight. This is an
important result to highlight because it demonstrates a very different correlation between charge
carrier mobilities and molecular weight than what is commonly observed for CPs which exhibit
superior charge carrier mobilities with increasing molecular weights especially for the molecular
weight range investigated for these PvDMPTAs.
In the following discussion of a 2011 report by Thelakkat et al. on poly(perylene bisimides)
(PPBIs), the focus will be shifted away from substituent effects towards a structural variable that
has been kept constant in all previously described studies: the length of the spacer connecting the
pendant group to the polymer backbone.
93
To allow for isolated variation of these specific variables
independently of molecular weight and tacticity effects a single p-propynyloxy-substituted styrene
polymer was synthesized which was then functionalized post-polymerization with the respective
pendant groups. Polymerization via NMRP of the silyl protected alkyne bearing monomer
followed by a deprotection with TBAF yielded the atactic parent polymer with a molecular weight
of 7.4 kg/mol and Ð = 1.11 which was then functionalized in copper-catalyzed azide-alkyne
cycloaddition (CuAAC) by a CuBr/PMDETA catalytic system in THF at room temperature with
the respective pendant groups bearing terminal azide affording polymers with molecular weights
of 55.6-59.7 kg/mol. By substituting the bisimide with N-swallow tails featuring hydrophobic alkyl
27

groups and hydrophilic oligoethyleneglycol groups two families of NCPEPs, PPBI-1s with
hydrophobic groups and PPBI-2s with hydrophilic groups, were synthesized and the properties of
the respective polymers could be contrasted between these families. Additionally, for each family
the spacer connecting the polystyrene derived backbone to the perylene bisimide moieties was
varied from (CH2)6 to (CH2)8 and (CH2)11 yielding a total of six NCPEP (Figure 1.6a). Quantitative
functionalization in CuAAC could be follow through
1
H-NMR spectroscopy and FTIR by
disappearance of the C≡C vibration band at 2120 cm
-1
and the C≡C-H vibration band at 3286 cm
-
1
.
In UV/Vis absorption spectra all polymers showed similar absorption spectra displaying the
characteristic absorption maxima of PBI at 527, 491 and 464 nm. Red-shifted emission indicative
of a pronounced π–π stacking of the PBI moieties was observed with both hydrophobic alkyl
groups and hydrophilic oligoethyleneglycol groups. In PL spectra however the fluorescence peak
at 611 nm for the hydrophobic polymers was red shifted to 624 nm in the hydrophilic ones likely
due to a smaller delocalization length in the excited state in the latter. Effects of spacer length
could not be observed in UV/Vis or PL measurements. However, structural and thermal properties
were investigated through SAXS and DSC measurements which revealed a distinct effect of the
spacer length on Tm and Tg; both decreased with increasing spacer length regardless of the nature
of the N-swallow tail. For the polymers with hydrophobic side chains the six and eight carbon
spacer afforded crystalline polymers but extending the spacer to eleven carbons resulted in an
amorphous polymer. With hydrophilic side chains on the other hand all polymers were amorphous
regardless of spacer length. Spacer length effects were attributed to increased plasticization of the
backbone as a result of longer alkyl spacers. The effect of the hydrophilic side chains leading the
more amorphous polymer structures was reasoned to stem from the higher flexibility and space-
28

filling properties of oligoethyleneglycol that had previously been known for low molecular PBIs
which consequently hindered the formation of ordered liquid crystalline or crystalline structures.
Overall, a distinct effect of both spacer length and of the nature of the pendant side chains on the
physical properties of the resulting polymers was demonstrated. In the context of this study we
want to highlight the importance of the utilized post-polymerization approach for being the only
method that allows for investigating isolated spacer length and pendant group effects across
identical polymer backbones. Additionally, this report is one the few examples of poly(styrene)
derived NCPEP made via this methodology.
Building on this family of poly(perylene bisimides) (PPBIs), Thelakkat et al. then turned to
investigating effects of the nature of the π-conjugated pendant unit itself in addition to
investigating the effects of the previously introduced hydrophilic and hydrophobic side chains on
the N-swallow tail of PPBI-1 and PPBI-2.
94
The two PPBIs with side chains of varied
hydrophobicity were compared to poly(perylene diester imide) (PPDEI) and poly(perylene diester
benzimidazole (PPDEB) but in this study the spacer length was fixed at (CH2)6 for all polymers
(Figure 1.6a). Similarly to their previous study on PPBIs, a stereorandom p-propynyloxy-
substituted, silyl protected styrene polymer was synthesized via NMRP and subsequently
deprotected to give a parent polymer with a molecular weight of 7.40 kg/mol and Ð = 1.11 that
was then functionalized with the respective pendant groups in CuAAC reactions. The final
NCPEPs had molecular weights of 15.0-59.7 kg/mol and glass transition temperatures of 124-182
°C with the exception of PPDEB which did not show a glass transition. In agreement with the
previously discussed study on PPBIs with the same side chains, the polymer bearing a hydrophobic
alkyl side chain showed a liquid crystalline strucutre while the one with the hydrophobic
oligoethyleneglycol side chain showed fully amorphous properties. Both PPDEB and PPDEI
29

showed liquid crystalline structures in DSC measurements that was maintained upon cooling to
room temperature suggesting a “frozen in” liquid crystalline state due to the viscosity of the
materials.
UV/Vis absorption spectroscopy showed similar spectra for the two PPBIs with absorption
maxima around 537 and 498 nm. Owing to its smaller conjugated system PPDEI showed a blue-
shifted absorption with maxima at 507 and 478 nm while the extended conjugated system in
PPDEB gave rise to a featureless broad absorption up to 700 nm with a maximum at 528 nm. PL
spectra revealed strong PL quenching in PPDEB but rather high PL intensity for PPDEI.
Significantly reduced PL intensity and thus increased quenching for the PPBI with a hydrophobic
side chain compared to the one with a hydrophilic side chain indicated higher electronic interaction
of the perylene cores when they are substituted with the hydrophilic side chain. Energy levels and
band gaps as determined from CV measurements demonstrated a clear correlation of the size the
conjugated system on the pedant units with the resulting band gap of the corresponding polymers.
PPDEI with the smallest π-system exhibited the highest band gap of 2.12 eV, followed by 2.05 eV
for the two PPBIs and PPDEB with the most extended π-system exhibiting the smallest band gap,
1.82 eV, a LUMO energy of -3.86 eV and a HOMO energy of -5.68 eV, both of which were the
highest within this family of polymers. OFETs for charge carrier mobility measurements were
fabricated however no mobilities could be measured with PPDEB or PPDEI which was explained
by wetting/dewetting issues and interface effects in the devices as well as unfavorable alignment
of the polymers within the transistor channels. For the PPBIs, electron mobilities in the order of
10
-6
cm
2
/V∙s were measured after annealing. SCLC electron-only devices of the general structure
glass/ITO/PEDOT:PSS/polymer/Ca/Al and hole-only devices of the general structure
glass/ITO/PEDOT:PSS/polymer/Au allowed for charge carrier mobility measurements across all
30

four NCPEPs. For the PPBIs, annealing above their Tg led to significantly increased mobilities, an
effect that could not be observed for PPDEB or PPDEI. PPDEB and both PPBIs were excellent
electron transporting material with μe = 6.00 × 10
-4
cm
2
/V∙s for PPDEB, μe = 1.00 × 10
-3
cm
2
/V∙s
for PPBI with a hydrophobic side chain and μe = 1.00 × 10
-2
cm
2
/V∙s for PPBI with a hydrophilic
side chain. Consistent with established literature on perylene imide derivatives as n-type
semiconductors, their hole mobilities were at least two orders of magnitude lower demonstrating
preferred electron transport though the LUMO rather than hole transport via the HOMO. For
PPDEI however the measured hole mobility of μh = 7.00 × 10
-6
cm
2
/V∙s was slightly higher than
its μe of 5.00 × 10
-6
cm
2
/V∙s suggesting that modification of the perylene core with diester and
imide units can lead to a more pronounced p-type rather than the typical n-type behavior. The
lower absolute value of μe in PPDEI compared to PPDEB was explained by the less electron-
deficient PDEI groups. While the extended π-system of PPDEB lead to improved optical
properties, mobilities were lower than for the PPBI polymers. Aside from these significant effects
of the nature of the pendant group itself, within the PPBIs a clear effect of the respective side
chains was observed with the hydrophilic side chain bearing PPBI exhibiting a μe that was an order
of magnitude higher than μe for the hydrophobic side chain bearing polymer. This drastic
difference was tentatively attributed to differences in the polymer packing and morphology as seen
in the morphological characterization where the PPBI bearing hydrophilic side chains exhibited a
less ordered, amorphous morphology.
Extension of the pendant π-conjugated system was also studied by Reichmanis et al. in 2010,
however, in this report on polystyrene-derivatives substituted with different conjugated
oligothiophenes.
95
The two NCPEPs poly(5-hexyl-5’’-(4-vinylphenyl)-2,2´:5´,2´´-terthiophene)
(PH3TS) and poly(5-hexyl-5´´´´-(4-vinylphenyl)-2,2´:5´,2´´:5´´,2´´´:5´´´:2´´´´-quinquethiophene)
31

(PH5TS) (Figure 1.6a) were synthesized via Stille-coupling of the respective brominated
oligothiophene with the same poly(4-(2-thiophenyl)styrene) parent polymer after post-
polymerization functionalization with tributyltin yielding polymers with molecular weights of 19.7
and 28.1 kg/mol respectively and Ð ≤ 2.25. The atactic parent polymer was synthesized through
AIBN initiated radical polymerization of 2-(4-vinylphenyl)thiophene in toluene at 70 °C yielding
poly(2-(4-vinylphenyl)thiophene) (PTS).
Thermal characterization via DSC of the parent polymer prior to stannylation showed an
increased Tg of 152 °C compared to ~ 100 °C for neat polystyrene while the functionalized
NCPEPs did not show clear glass transitions which was assumed to be the result of highly hindered
segmental motions. In agreement with the results obtained from X-ray diffractometry (XRD), no
crystallization peaks were identified suggesting amorphous morphologies for PH3TS and PH5TS.
UV/Vis absorption spectra displayed absorption maxima corresponding to the respective π–π*
transition of the (oligo-)thiophenes with an increasing red-shift as the size of the conjugated system
increases: 293 nm for PTS, 383 nm for PH3TS and 407 nm for PH5TS. Corresponding
bathochromic shifts were also observed in PL spectra with emission peaks at 411, 485 and 514 nm
for PTS, PH3TS and PH5TS respectively. CV measurements to calculate the frontier energy levels
and to test their oxidative stability revealed significantly different solubilities for the two
oligothiophene-NCPEPs with PH5TS having a solubility in DCM that was so limited that a
uniform film of known thickness could hardly be deposited. For PH3TS the observed oxidation
process was found to be reversible while for PH5TS no clear reduction peak could be identified.
While the peak for the oxidation for PH3TS was found to be at 0.65 V vs. Fe/Fe
+
, this peak shifted
to ~ 0.50 V for PH5TS suggesting decreased oxidation potentials with increasing conjugation
32

lengths in this type of NCPEPs. Energy levels were calculated to be -5.34 and -5.22 V for the
HOMOs and -2.74 and -2.85 eV for the LUMOs of PH3TS and PH5TS respectively.
A series of “push-pull” chromophore containing NCPEPs based on the well-established cyano-
substituted poly(p-phenylenevinylene) system with varied conjugation length and varied donor
(D) and acceptor (A) functionalities within the pendant groups was reported by Evans et al..
96
The
four stereorandom polymers in this study, depicted in Figure 1.6a, were poly(dimethoxyphenyl-
vinylphenyl-acrylonitrile) (PDMPPA), poly(diethylamino-phenyl-vinylphenyl-acrylonitrile)
(PDEPPA), poly(diphenylamino-phenyl-vinylphenyl-acrylonitrile) (PDPPPA) and
poly(ditolylamino-phenyl-vinylbenzoimidoyl cyanide) (PDTPBI) which were synthesized via
AIBN initiated radical polymerization in benzene affording molecular weights of 0.60-2.30 kg/mol
and dispersities of Ð = 1.74-2.80.
In the UV/Vis absorption spectra PDEPPA exhibited a red-shifted absorption maximum
relative to PDMPPA which was attributed to the stronger electron donating abilities of the
diethylamine moiety compared to the methoxy groups resulting in greater charge transfer character
in PDEPPA. PDPPPA showed absorption characteristics that were nearly identical to those of
PDEPPA indicative of similar charge donating abilities of triphenylamine (TPA) and diethylamine
and minimal effect of the TPA moiety on the effective π-conjugation length in the chromophore
of the pendant group. For PDTPBI however there is a significant bathochromic shift attributed to
the superior electron withdrawing ability of the cyanoimine group over the cyanovinylidene group.
Owing to TPAs strong charge donating and hole-transporting capability only PDPPPA and
PDTPBI were considered for all further characterizations. In PL spectra PDTPBI exhibited a
similar bathochromic shift relative to PDPPPA as described for the UV/Vis absorption spectra.
Unlike for PDPPPA, the Stokes shift for PDTPBI was found to be highly solvent dependent
33

suggesting an intramolecular charge re-distribution in the luminescent state of the polymer that is
more favorable in PDTPBI due to cyanoimine being the stronger electron withdrawing moiety.
Energy level calculations from CV measurements showed similar HOMO energies of -5.1 and -
5.4 eV for PDPPPA and PDTPBI respectively but a significantly lower LUMO in the latter leading
to an increase of the band gap from 2.6 to 2.2 eV. Because of its similar energy levels to poly(2,7-
(9,9-di-n-octylfluorene)-(1,4-phenylene-((4-secbutylphenyl)imino)-1,4-phenylene)) (F8TFB), the
hole transport material used in benchmark OLED devices alongside poly(2,7-(9,9-di-n-
octylfluorene)-3,6- benzothiadiazole) (F8BT) for electron transport, PDPPPA was paired with
F8BT and yielded OLED device efficiencies that were about 20% of the efficiency of optimized
benchmark F8TFB/F8BT devices. Both PDPPPA and PDTPBI were also mixed with PCBM and
used as the active layer in ITO/PEDOT:PSS/polymer:PCBM/Ca/Al bulk heterojunction (BHJ)
OPV devices. With the optimal ratio of polymer:PCBM = 1:4 nearly identical FF values of 29 and
efficiencies of 0.13% and 0.29% were measured for PDPPPA and PDTPBI respectively. The rather
low efficiencies were believed to be the result of limited visible light absorption of both polymers.
Annealing did not lead to any significant changes in the device performances. Bulk mobilities μB
measured by the Photo-CELIV technique were below the detection limit of 10
-6
cm
2
/V∙s, consistent
with the disordered, amorphous solid-state structure expected for such NCPEPs. This was
supported by atomic force microscopy (AFM) topographic imaging of polymer:PCBM films that
displayed homogenously mixed, smooth layers without signs of phase separated domains
indicative of a highly disordered microphase structure for both polymers. Overall, successful
tuning of absorption properties and band gaps through structural modifications of the electro-active
pendant groups in such NCPEPs was demonstrated.
34

While this study, as well as the previous examples by Reichmanis et al. and Thelakkat et al.,
focused exclusively on polymers with atactic backbones for which the pendant groups were tuned,
in the following report structural complexity of the pendant group is reduced to carbazole and
instead polymer with different tacticities are investigated. Chiellini et al. studied the effect of
tacticity in poly(4-(9-carbazolylmethyl)styrene) on the properties of the resulting polymers by
synthesizing the respective atactic, isotactic and syndiotactic NCPEPs.
97
They also compared two
isomeric pendant groups, 4-(9-carbazolylmethyl)styrene and 3-(9-carbyzolylmethyl)styrene,
however for the latter pendant group only an atactic polymer was reported. It was found that
homopolymers of both 4-(9-carbazolylmethyl)styrene (poly(4-CzMe-styrene)) and 3-(9-
carbyzolylmethyl)styrene (poly(3-CzMe-styrene)), depicted in Figure 1.6a, could be obtained
from AIBN initiated radical polymerization yielding molecular weights of 21.9 and 18.6 kg/mol
respectively and from Al(
i
Bu)3/TiCl4 catalyzed Ziegler-Natta polymerization yielding molecular
weights of 37.9 and 50.8 kg/mol respectively with both methods yielding virtually the same
stereorandom backbone tacticity as determined from
13
C-NMR spectroscopy. Based on
unsuccessful copolymerization attempts of these monomers with (S)-4-methyl-1-hexene and N-
vinylcarbazole under the Ziegler-Natta conditions the authors explained these results with an
incompatibility of the characteristic coordination mechanism in Ziegler-Natta polymerization with
carbazole containing monomers. To achieve prevailing stereoregular poly(4-(9-
carbyzolylmethyl)styrene), the synthetic route was modified to polymerization of styrene with
AIBN, AlEtCl2 and Al(
i
Bu)3/TiCl3 respectively yielding polystyrenes with dyad tacticities ranging
from 10% (r) to 72% (r) that were then functionalized post-polymerization in the para-position of
the benzene moieties with CH3OCH2Cl followed by a NaOH/TBAB catalyzed substitution with
carbazole to yield the final electroactive pendant groups.
35

Fluorescence emission spectra were nearly identical for all polymers and only displayed
absorption bands at 350 and 370 nm corresponding to carbazole emission. Emission spectra were
independent of the chemical structure of the pendant group between the two investigated isomers
and also appeared to be independent of the backbone tacticity for this particular family of NCPEPs.
No excimer emission and instead only emission typical of isolated carbazole was observed from
which a very low concentration of excimer-forming sites was concluded.
After optimizing the Ziegler-Natta polymerization conditions, Venditto et al. were studying
the same family of atactic, isotactic and syndiotactic poly(4-CzMe-styrenes) (Figure 1.6a) but at
higher levels of stereocontrol.
98
All polymerizations were carried out in toluene at 50 °C with a
dichloro{1,4-dithiabutanediyl-2,20-bis[4,6-bis(2-phenyl-2-propyl)phenoxy]}titanium/MAO
catalytic system affording >98% (mmmm) pentad isotactic poly(3-(9-carbyzolylmethyl)styrene)
with a molecular weight of 1.45 kg/mol and Ð = 1.50. A trichloro-(pentamethylcyclopentadienyl)
titanium/MAO catalytic system afforded a 87% (r) dyad syndiotactic polymer with a molecular
weight of 2.2 kg/mol and Ð = 2.20 while a Ni(acetylacetonate)2/MAO catalytic system afforded
an atactic polymer with a molecular weight of 1.8 kg/mol and Ð = 1.80.
Thermal characterization by DSC revealed decreasing Tg with a decreasing degree of
stereoregularity from 178 °C for the isotactic polymer to 161 °C for the atactic polymer. In
agreement with the DSC measurements, X-ray diffraction pattern revealed an amorphous
morphology for all polymers. FTIR spectroscopy of the two stereoregular polymers showed very
similar absorbance with prominent bands at 628 and 629 cm
-1
and an additional weak band for the
isotactic sample centered around 600 cm
-1
. Compared to spectra for stereoregular polystyrenes
reported in literature this led the authors to conclude that stereoregular poly(4-(9-
carbyzolylmethyl)styrene), unlike polystyrene, has limited differences in accessible conformation
36

distributions of polymer backbone chains with no apparent clear distinction between a helical and
a trans-planar backbone chain conformation which was believed to be a result of the presence of
the bulky carbazole groups that reduce the conformational freedom of the polymer chains.
Fluorescence spectroscopy revealed the presence of emission bands at 355 and 373 nm
characteristic for carbazole in both stereoregular polymer, however the isotactic polymer also
exhibited a peak at 394 nm corresponding to excimer emission from partially overlapping adjacent
carbazoles and a peak at 412 nm corresponding to excimer emission from fully overlapping
adjacent carbazoles while the syndiotactic polymer only exhibited the peak stemming from
partially overlapped excimer emission. This was the first report of a synthesis and the
microstructural characterization of highly isotactic PSK.

1.2.2.2 Random copolymers of poly(styrene) NCPEPs

While a number of the previously discussed studies were varying the NCPEP structures
through functionalization with different pendant groups, Hoang et al. were varying the general
polymer structure by synthesizing random polystyrene-based copolymers with increasing ratios of
styrene moieties functionalized with a pendant anthraquinone (AQ), poly(p-9,10-anthraquinone-
2-carbonyl-styrene)-co-styrene (PAQCS-co-PS) (Figure 1.7a).
99
The random copolymers were
synthesized by post-polymerization functionalization of stereorandom polystyrene with varying
amounts of 2-anthraquinonecarbonylchloride in the presence of aluminum chloride resulting in
molecular weights ranging from 0.8 to 46.8 kg/mol with AQ contents of 18 to 49% and Ð ≤ 1.35.
Electrochemical characterization via CV and cathodic peak current measurements were able
to demonstrate a clear molecular weight effect on peak currents with higher Mn leading to lower
37

peak currents at fixed scan rates. This was explained through the dependance of the diffusion
coefficient D on Mn which in turn follows the relationship ip ~ D
0.5
in regard to the peak current ip.
However, outside of molecular weight effect no correlation could be drawn between the varying
content of AQ in the copolymers and their electrochemical properties. Instead, all polymers
exhibited the electrochemical behavior of free, molecular AQ species despite the most AQ-rich
copolymer having a statistical probability of greater than 65% for moieties with adjacent AQ
pendants that could allow for near-neighbor interactions.
In a study on similar random copolymers also containing unfunctionalized styrene alongside a
styrene-derived pendant, in this case (1-pyrenyl)styrene (PyS) rather than AQ, Liu et al. set out to
investigate the effects of varied molar ratios of the two co-monomers on the thermal, optical,
photophysical and electrochemical properties of the respective copolymers (PS-co-PPyS).
100
Three
polymers with styrene:pyrenyl-styrene ratios of 21.4:1, 3.9:1 and 1.4:1 with their general structure
depicted in Figure 1.7a were synthesized through AIBN initiated radical polymerization with
varied feed ratios of the two monomers. The obtained copolymers had molecular weights of 12.8-
23.2 kg/mol and dispersities of Ð = 2.21-2.76.
Tg of the copolymers were found to increase with increasing PyS content from 114 to 143 and
182 °C. UV/Vis absorption spectroscopy revealed identical absorption maxima at 280 and 346 nm
for all copolymers corresponding to styrene and PyS respectively. In PL spectra emission peaks
were observed, at 405 nm corresponding to PyS monomer emission and at 468 nm corresponding
to PyS excimer emission. With increased PyS content in the polymer the probability for excimer
formation increased and consequently the intensities of the two bands relative to each other shifted
in favor of the excimer emission peak. Energy level calculations from CV measurements showed
a slight increase in the HOMO energy from -5.25 to -5.20 eV when increasing the PyS content
38

from 3.9:1 to 1.4:1 while LUMO energies remained virtually unchanged; for the styrene:PyS =
21.4:1 copolymer no energy levels could be determined due to the low ratio of PyS groups. The
copolymers were tested in OFET memory devices with pentacene as the organic model
semiconductor. Pentacene proved to be compatible with all copolymers affording respectable ON
currents around 10
-4
A and hole mobilities that decreased slightly with increased ratios of PyS of
0.42, 0.39 and 0.29 cm
2
/V∙s respectively. Measurements of the memory window demonstrated that
the charge storage capabilities of the copolymers were largely dominated by the ratio of PyS. AFM
topography imaging of copolymer films on SiO2 suggested smooth, continuous and pin-hole free
surface morphologies for all copolymers. Considering these results and the nearly identical OFF
currents for all three OFET devices, the observed differences in OFET memory properties were
attributed to the comonomer ratios of the pendant copolymers.
While also relying on a poly(styrene) derived random copolymer as the general polymer
structure, Thelakkat et al. were aiming to incorporate a distinctly different type of pendant group,
the established small molecule acceptor for OPV applications, PCBM. A family of stereorandom
statistical copolymers, P4MS-co-P4(PCBM)S, (Figure 1.7a) was synthesized via RAFT co-
polymerization of p-methoxy-styrene with p-tbutoxy-styrene in varied comonomer ratios followed
by acid catalyzed cleavage of the tbuyl-groups and functionalization of the resulting hydroxyl-
groups with phenyl-C61-butyric acid (PCBA) in Steglich esterifications.
101
As determined from
MALDI, four functionalized copolymers with molecular weights of 19.6-35.1 kg/mol were
obtained with PCBM contents ranging from 30 to 64 wt.-%. The copolymer with 64 wt.-% PCBM
already precipitated during the esterification reaction and could only be redissolved in DCB at 100
°C which was therefore determined as the maximum PCBM-content to maintain solution
processability. This was also the only copolymer for which quantitative functionalization of the
39

hydroxyl-groups with PCBA was shown, while esterification efficiencies for the other copolymers
were around 56-67%.
In UV/Vis absorption spectroscopy all copolymers displayed the typical absorption bands of
pristine PCBM at 258 and 328 nm regardless of the PCBM-content in the polymer. CV
measurements for the three copolymers with lower PCBM wt.-% allowed for calculation of the
respective LUMO energies which were nearly identical at -3.80 eV and very similar to pristine
PCBM at -3.82 eV. Tg for these polymers as determined from DSC increased by 50-90 °C
compared to their unfunctionalized parent polymers. The effect was more pronounced at higher
wt.-% of PCBM and was attributed to the steric hinderance stemming from attachment of fullerene
moieties and the strong intermolecular interactions between them. Electron mobilities were
measured for the three copolymers with lower PCBM ratios as well as for blends of the respective
unfunctionalized parent polymers with small molecule PCBM via the SCLC method with
ITO/PEDOT:PSS and Ca/Al electrodes. The blend devices show an exponential increase in μe with
increasing PCBM content, however even for the highest content of 50 wt.-% a rather low μe of
6.00 × 10
-5
cm
2
/V∙s was obtained, about two orders of magnitude lower than what is reported for
pristine PCBM. For devices with the functionalized copolymers mobilities varied by about an
order of magnitude over the three copolymers with the highest μe of 1.00 × 10
-4
cm
2
/V∙s for the
copolymer with an intermediate PCBM ratio of 37 wt.-%. The improved mobilities compared to
the blend devices were explained by enhanced percolation networks in the pendant fullerenes.
AFM phase images shown in Figure 1.7c were similar for all three copolymers and showed
effective suppression of fullerene aggregation by covalently attaching them to a polymer backbone
unlike AFM images of blends of the unfunctionalized PS-OH polymer with molecular PCBM
which exhibited significant phase separation especially as the PCBM loading increased. These
40

results were supported by TEM of copolymer thin films which were fully homogenous. Films of
the unfunctionalized polymers blended with small molecule PCBM however showed phase-
separated films with numerous PCBM clusters demonstrating that by grafting the PCBM to a
polymer backbone the phase-separated, crystalline morphology can successfully be converted to
an amorphous one with a homogenous distribution of PCBM moieties which is an impressive
example of how controlled microphase morphologies that can be realized with NCPEPs.
Additionally, it is worth noting from a synthetic standpoint that with such a NCPEP the widely
used small molecule acceptor PCBM can be incorporated into a polymer which cannot be realized
with CPs.

1.2.2.3 Block copolymers of poly(styrene) NCPEPs

Aside from the previously discussed examples of poly(styrene) based random copolymers, a
number of highly relevant studies rely on polymers with the more complex architecture of block
copolymers. For instance Jäger et al. were investigating electronic effects of styrenic triarylamine-
polymers through introduction of electron-withdrawing and -donating substituents in block and
random copolymers (Figure 1.7a).
92
Five vinylphenyl-amine monomers disubstituted with
methoxy-, methyl-, n-butyl-, trifluoromethyl- and fluoro-groups were polymerized via nitroxide-
mediated radical polymerization (NMRP). PvD(substituent)TPA homopolymers in molecular
weights of 2.6-10.6 kg/mol as well as statistical- and block-copolymers, PvD(X)TPA-co/b-
PvD(Y)TPA, in molecular weights of 25.0-39.0 kg/mol with Ð ≤ 1.42 were synthesized.
Independently of the substituents all polymers exhibited a strong band around 300 nm in their
UV/Vis absorption spectra. Upon oxidation a bathochromic shift to 370 nm was observed for all
41

polymers along with the appearance of an additional absorption peak around 700 nm. The shift of
the additional peak however proved to be substituent-dependent with the methoxy-substituent
exhibiting the largest red-shift, 736 nm, and all other polymers exhibiting a relative hypsochromic
shift that was more pronounced for highly electron-deficient substituents. Emission peaks in PL
spectra showed a distinct influence of the substituent as well. The methoxy-substituted polymer
showed maximum emission around 427 nm whereas increasing electron-withdrawing character of
the substituent caused an increasingly hypsochromic shift most significantly in the fluoro-
substituented polymer which had an emission maximum at 410 nm. Oxidation potentials were
measured through CV with electron-withdrawing substituents giving the highest oxidation
potential, followed by identical potentials for the two alkyl substituents and finally lower potentials
for the electron-donating methoxy-substituent spanning an overall potential window from 0.20-
0.50 V. The copolymer CVs showed overlapping oxidation waves of the corresponding blocks
indicative of independent oxidation of the differently substituted repeat units. In the block-
copolymers contributions of the individual blocks relative to their block-ratios, as determined from
1
H-NMR spectroscopy, on the electrochemical activities of the polymers could be shown.
Furthermore, UV/Vis redox titration of the block-copolymers demonstrated directional charge
transfer driven by the redox potential difference between the blocks. This is a key result showing
that NCPEPs are not only functioning electroactive materials but in advanced architectures such
as these block copolymers they can allow for an inherent driving force sufficient for directional
charge transfer which is highly relevant for numerous organic electronics applications as
demonstrated for instance by Meyer et al. who reported the versatility of similar photoredox-active
macromolecular architectures for light-induced charge separation.
102,103

42

Building on their library of previously discussed PvDMTPA and PvDMTPD homopolymers,
Thelakkat et al. extended the complexity of these NCPEP structures by employing them as the
donor (D) block in donor-acceptor (D-A) block copolymers with a perylene diimide acrylate
(PerAcr) acceptor (A) block.
104
The block copolymers depicted in Figure 1.7a were synthesized
via NMRP with PvDMTPA and PvDMTPD serving as the macroinitiators for the polymerization
of the second PerAcr-block. Two PvDMTPA-b-PPerAcr copolymer with molecular weights of
34.6 kg/mol and 88.3 kg/mol with PerAcr contents of 72 and 84 wt.-% respectively as well as a
PvDMTPD-b-PPerAcr copolymer with a molecular weight of 26.5 kg/mol at a PerAcr wt.-% of
81 % were synthesized.
The quenching efficiencies of the block-copolymers in fluorescence (PL) spectroscopy were
measured in comparison to a perylene (PPerAcr) homopolymer and a blend of PPerAcr and
PvDMTPA homopolymers with the same composition as their higher molecular weight
copolymer. Significantly decreased PL intensities of 30% for the homopolymer blend and 77% for
the copolymer in respect to PPerAcr were observed which was explained through electron transfer
from D to A which is enhanced in the copolymer due to the larger interface between D and A in
the nanosized block domains whereas the polymer blend was assumed to phase separate forming
macroscale size domains of pristine PPerAcr and PvDMTPA respectively. In the copolymers the
microphase separation was investigated by transmission electron microscopy (TEM) depicted in
Figure 1.7b which revealed short, worm-like structures for the higher Mn PvDMTPA-b-PPerAcr
polymer and longer nanowire-like structure for the lower Mn polymer while PvDMTPD-b-PPerAcr
exhibited thinner, short wire-like structures, presumably stemming from efficient perylene diimide
π–π stacking. Thin-film solar cell device testing resulted in almost identical FF values for all
polymer but significantly increased short-circuit currents for the lower Mn PvDMTPA-b-PPerAcr
43

and for PvDMTPD-b-PPerAcr of 1.14 and 1.21 mA/cm
2
respectively compared to 0.24 mA/cm
2

for the higher Mn PvDMTPA-b-PPerAcr. Consequently, device efficiencies for the former two
copolymer were higher by almost an order of magnitude with the lower Mn PvDMTPA-b-PPerAcr
giving the best efficiency of 0.32%. This report is one of the best examples for showcasing the
high levels of control over the microphase structure that NCPEP block copolymers offer and how
even minor changes to the chemical structure of just one of the blocks can lead to distinctly changes
in the microphases for the resulting polymers.
In a follow-up study by Thelakkat et al. on this type of D-A block copolymers, PvDMTPA-b-
PPerAcr and PvDMTPD-b-PPerAcr were supplemented by PvTPA-b-PPerAcr with an
unsubstituted poly(vinyltriphenylamine) as the D block (Figure 1.7a).
66
The same three
PvDMTPA-b-PPerAcr and PvDMTPD-b-PPerAcr as discussed for the previous study were
compared to PvTPA-b-PPerAcr with a molecular weight of 26.9 kg/mol, Ð = 1.50 and a PerAcr
wt.-% of 86% also made from NMRP.
104
The Tg of PvTPA-b-PPerAcr was slightly higher than for
the other block copolymers at 150 °C.
Additionally to Tg stemming from the amorphous D-blocks, DSC analysis showed distinct
peaks for melting temperature Tm between 183 and 198 °C stemming from the A-blocks for all
copolymers indicating the presence of phase-separated domains. This was confirmed through TEM
imaging showing long wire-like and worm-like structures of the PPerAcr-segments. PvTPA-b-
PPerAcr and lower Mn PvDMTPA-b-PPerAcr showed longer wire-like structures and longer
amorphous blocks whereas higher Mn PvDMTPA-b-PPerAcr and PvDMTPD-b-PPerAcr exhibited
shorter worm-like structures and shorter amorphous blocks suggesting that long nanostructure
formation for this type of copolymer requires macroinitiator molecular weight of 10-12 kg/mol at
a PPerAcr wt.-% of 72-86%.
44

Figure 1.7 a) Chemical structures of poly(styrene) derived NCPEP copolymers. b) Cross sectional
transmission electron micrographs of block copolymers PvDMTPA-b-PPerAcr (a), PvDMTPA-b-
PPerAcr (b) and PvDMTPD-b-PPerAcr (c). The samples were tempered at 210 °C, embedded in
epoxy resin, cut and stained with RuO 4. Reprinted with permission from Sommer et al.
104
Copyright
2007 Cambridge University Press. c) AFM topography images showing films of P4MS-co-
P4(PCBM)S (30 (1), 37 (2) and 51 wt.-% PCBM (3)) and blends of PCBM:PS-OH in varying
compositions (30, 40, 50 wt.-% PCBM) prepared for the SCLC measurements. Reprinted with
permission from Hufnagel et al.
101
Copyright 2014 American Chemical Society.
45

Energy levels as determined from CV revealed almost identical LUMO energies of ~3.60 eV
and HOMO energies of 4.96 eV for PvDMTPA-b-PPerAcr and PvDMTPD-b-PPerAcr but of 5.24
eV for PvTPA-b-PPerAcr. The increased HOMO energy for PvTPA-b-PPerAcr was explained by
the dimerization of the triphenylamine moieties upon electrochemical oxidation, a side-reaction
that is avoided in the other block copolymers through substitution of the para-position of the
triphenylamine and stabilization of the radical cation with electron-rich groups. The copolymers
were tested in single layer OPV devices of the general structure ITO/PEDOT:PSS/copolymer/Al.
While FF values were virtually identical across all devices, PvTPA-b-PPerAcr and higher Mn
PvDMTPA-b-PPerAcr gave low JSC of 0.23 and 0.24 mA/cm
2
which resulted in low efficiencies
of 0.065% and 0.052% respectively while PvDMTBD-b-PPerAcr and lower Mn PvDMTPA-b-
PPerAcr gave significantly higher JSC of 1.21 and 1.14 mA/cm
2
which resulted in higher
efficiencies of 0.262% and 0.323% respectively. The low JSC of PvTPA-b-PPerAcr was ascribed
to the low D-A HOMO offset which led to less efficient charge transfer and made overcoming the
exciton bonding energy of the perylene diimde group less favorable. In between the copolymers
of PvDMTPA-b-PPerAcr the copolymer with the longer hole-conducting block and consequently
higher Mn assumed a shorter worm-like structure which was reasoned to be less favorable for
charge percolation than the longer wire-like structure of the lower Mn copolymer. The good
performance of the PvDMTPD-b-PPerAcr was assigned to the higher charge carrier mobility of
TPD which was expected to outperform TPA by an order of magnitude.
Investigating the effects of the structure of the pendant moiety on the properties of block
copolymers was also the focus of a 2010 study by Wilson et al. in a family of atactic triarylamine-
, phenyl-benzothiadiazole- and benzyloxy-phenyl-benzothiadiazole-derived homopolymers
shown in Figure 1.6a and block-copolymers shown in Figure 1.7a.
105
Homopolymers PvMeTPA,
46

PvPhBnTDZ and P(4-Ar)-vBzPhBnTDZs were synthesized by free-radical polymerization.
Significant differences in the solubility of the monomers in the polymerization solvent led to
molecular weights ranging from 4.7 kg/mol for p-toly substituted P(4-Ar)-vBzPhBnTDZ and 5.9
kg/mol for PvPhBnTDZ to 48.0 kg/mol for the PvMeTPA. PvMeTPA and substituted P(4-Ar)-
vBzPhBnTDZs were also synthesized via the more controlled Reversible addition-fragmentation
chain-transfer polymerization (RAFT) with the RAFT agent trithiocarbonate yielding molecular
weights of 6.2-13.4 kg/mol at low dispersities of Ð ≤ 1.24. These conditions were then translated
to the synthesis of the block copolymer. All block copolymers had one PvMeTPA-block and one
P(4-Ar)-vBzPhBnTDZ-block that was substituted with either methyl-thiophene or hexyl-
bithiophene (Figure 1.7a) while the order of the two blocks was varied. Molecular weights of the
block copolymers were in the range of 14.0-52.1 kg/mol with Ð ≤ 1.64.
Despite significant variation of the conjugated moieties potentially inducing π–π stacking
within the NCPEPs, DSC and powder XRD measurement showed fully amorphous behavior for
all polymers with Tg in the range of 120-150 °C. For the homopolymers Tg was dependent on the
pendant group with the more rigid PvPhBnTDZ and PvMeTPA that were lacking solubilizing side
chains exhibiting the highest glass transition temperatures. The block copolymers only showed a
single Tg which was explained by the close range of the Tg of the homopolymers and in the case
of PvMeTPA-b-P(4-Ar)-vBzPhBnTDZ (Ar = hexyl-bithiophene) was ascribed to a bigger
influence of the second block on the thermal properties of the copolymer. For the benzothiadiazole
(BT) containing homopolymers a distinct influence of the size of the π-conjugated system on the
absorption bands could be overserved in the UV/Vis absorption spectra. PvMeTPA with the BT
moiety directly attached to the polystyrene-backbone and without additional substituents on the 7
position exhibited an absorption maximum at 360 nm while the substituted P(4-Ar)-
47

vBzPhBnTDZs all exhibited maxima at higher wavelength at 405 nm for the p-tosyl substituent,
450 nm for the methylthiophene substituent and 465 nm for the hexyl-bithiophene substituent, the
most extended π-system. The stronger bathochromic shift with the thienyl substituent relative to
the tosyl substituent was explained by the more electron-rich nature and thus stronger donating
character of the thienyl. PL spectra of the block-copolymers upon excitation at 350 nm which
corresponds to an absorption minimum for the substituted P(4-Ar)-vBzPhBnTDZ-block and was
therefore expected to selectively excite the PvMeTPA-block resulted in an emission peak at 585
nm, characteristic for the poly(vinyl-benzyloxy-phenyl-benzothiadiazoles), while the expected
emission peak at 424 nm for PvMeTPA was fully quenched indicating energy transfer between the
two electroactive blocks in the polymer. Excitation of the block copolymer and the corresponding
poly(vinyl-benzyloxy-phenyl-benzothiadiazole) at 450 nm resulted in comparable UV absorption
of the BT moieties in both polymers but showed an increased luminescence in the block copolymer
suggesting self-quenching due to aggregate formation of the BT groups in the homopolymer that
is reduced by introduction of a PvMeTPA block in the copolymer. Attempts to use the block
copolymer as a D-A active material in OPV devices were unsuccessful, however upon addition of
the strong electron acceptor phenyl-C61-butyric acid methyl ester (PCBM) in a ratio of 1:4 with
respect to the copolymer devices with FF values of 28 and an efficiency of 0.16% were obtained.

1.2.3 Poly(acrylate) NCPEPs
1.2.3.1 Homopolymers of poly(acrylate) NCPEPs

A poly(acrylate) derived NCPEP, poly(2-N-carbazolylethyl acrylate) (PCzEA), was the model
compound in a 1986 study by Oshima et al. to demonstrate the influence of the backbone tacticity
on the properties of the resulting polymer such as charge carrier mobilities.
106
An isotactic PCzEA
48

was synthesized from the functionalized monomer through a controlled anionic polymerization in
toluene at 30 °C with benzalacetophenone-ethylmagnesium chloride as the initiator while an
atactic polymer was obtained through radical polymerization in toluene at 60 °C with AIBN as the
initiator, both of which are shown in Figure 1.8a. The molecular weights for both polymers were
5.0 kg/mol with Ð of 4.8 and 2.3 and dyad tacticities as determined from
1
H-NMR of 96% and
46% respectively.
In fluorescence spectra no peaks corresponding to the excimer emission of partially or fully
overlapping carbazole moieties as previously described for other carbazole functionalized
NCPEPs such as PVK were observed. In X-ray diffraction measurements however a distinct
diffraction peak at 2Θ = 21.0° was observed for the isotactic polymer implying a crystalline
morphology while the broad halo observed for the atactic polymer would suggest an amorphous
morphology. Hole mobility measurements based on the TOF method revealed a mobility of μh =
1.70 × 10
-5
cm
2
/V∙s for the isotactic polymer which was about six times higher than the μh of 3.00
× 10
-6
cm
2
/V∙s measured for the atactic polymer demonstrating a clear dependance of charge
carrier mobilities on the stereoregularity of the PCzEA backbone. Importantly, this report was the
first to show superior charge carrier mobilities for a stereoregular NCPEP over its stereorandom
analogue.
In 2018 Thompson et al. were able to confirm backbone tacticity dependent charge carrier
mobilities for poly(2-N-carbazolylethyl acrylates) (PCzEAs) by fine tuning the dyad tacticities
across a family of nine PCzEAs with dyad tacticities ranging from 45 to 95%.
77
The polymers
depicted in Figure 1.8a were synthesized from the pre-functionalized monomer through radical
and controlled anionic polymerizations. AIBN initiated polymerization in toluene yielded PCzEA
of the lowest dyad isotacticity of 45%. Addition of the Lewis acids Y(OTf)3 and Sc(OTf)3 along
49

with n-butanol as a co-solvent in varying ratios gradually increased tacticities up to 66%, while
switching to an anionic n-BuLi initiated polymerization in toluene at increasing initiator ratio from
15 to 45 mol-% gave PCzEAs of tacticities up to 82%. The most isotactic polymer was obtained
by EtMgCl/chalcone initiated anionic polymerization with the same solvent. Molecular weights of
the polymers made form radical polymerization ranged from 15.3-27.5 kg/mol while the ones
made from anionic polymerization ranged from 5.5 to 7.4 kg/mol, all with Ð ≤ 4.0. UV/Vis
absorption spectra for all polymers showed the same characteristic carbazole π–π* and n–π*
transitions at 295, 330 and 344 nm. In PL spectroscopy however excimer emission peaks at 405
and 420 nm indicative of an increased π-staking of the carbazole pendant groups can only be
observed in PCzEAs with a dayd isotacticity of >60%. The most isotactic polymer showed
significantly decreased PL intensity which was explained by aggregation driven by increased π-
staking of the pendant groups. As shown in Figure 1.8b, hole mobility measurements of the as-
cast polymer films based on the SCLC technique demonstrated a clear correlation of charge carrier
mobilities and backbone tacticity with increasing mobilities from μh = 2.11 × 10
-6
cm
2
/V∙s to μh =
4.68 × 10
-5
cm
2
/V∙s as the stereoregularity of the respective PCzEAs increased. Mobilities were
even highrt in thermally annealed films with the 95% isotactic polymer exhibiting a μh of 2.74 ×
10
-4
cm
2
/V∙s, more than 16 times that of the 45% isotactic polymer. Significantly, building on the
observations of Oshima et al., this is the first study that unambiguously demonstrated a clear
relationship between backbone tacticity and charge carrier mobility over a wide range of degrees
of isotacticity.
The same PCzEA polymer was part of a family of atactic poly(N-( ω-carbazolylalkyl)acrylates)
(PCzXAs) with gradually increased spacer lengths from two to eight carbons as shown in Figure
1.8a for which Seno et al. investigated effects of that increase in spacer length.
107
The polymers
50

were synthesized from AIBN initiated polymerization of the pre-functionalized monomers in
benzene at 60 °C which yielded molecular weights of 5.3 to 96.0 kg/mol with longer spacers
generally affording lower molecular weights.
Thermal characterization demonstrated a gradual decrease of Tg from 105 to 12 °C with
increased spacer lengths for the respective polymers but possible explanations for this observation
were not discussed. Photoinduced voltage discharge measurements over time on aluminum
substrates were measured under strong flash exposure to create sufficient charge carriers in the
transit time to reach space charge limited conditions that can be related to charge carrier mobilities.
With longer spacers generally lower discharge rates were observed, however poly(2-N-
carbazolylpropyl acrylate) with a three carbon spacer was an outlier by displaying the lowest
discharge rate of all polymers. While no absolute values for charge carrier mobilities were
reported, it was noted that up to a six carbon spacer the poly(N-( ω-carbazolylalkyl)acrylates) gave
higher mobilities than the reference polymer PVK. Based on the referenced relationship of the
reported discharge measurement data with charge carrier mobility an estimated mobility of μ ~ 3
× 10
-7
cm
2
/V∙s can be inferred for the five carbon spacer polymer and superior mobilities of ~ 5 ×
10
-6
cm
2
/V∙s and ~ 3 × 10
-6
cm
2
/V∙s respectively for the three and the two carbon spacer polymers
indicating a decrease in mobility with longer spacers. However, in addition to effects of the spacer
length on charge carrier mobilities potential superimposed effect of molecular weight have to be
considered given that Mn of the three carbon spacer polymer is higher by an order of magnitude
compared to both the three and the five carbon spacer polymers especially in light of established
molecular weight effects in other NCPEP such as higher hole mobility in PCzETPMA with higher
Mn and Mn-dependent PL emission of OLEDs containing PVK.
108,109

51

Figure 1.8 a) Chemical structures of poly(acrylate) derived NCPEP homopolymers. b)
Relationship of hole mobilities for as-cast and annealed PCzEAs with increasing degrees of
isotacticity. Reprinted with permission from Samal et al.
77
Copyright 2018 American Chemical
Society. c) Relationship of hole mobilities for two families of as-cast and annealed PCzXAs with
different degrees of isotacticity with spacer lengths ranging from 2 to 12 carbons. Reprinted with
permission from Samal et al.
110
Copyright 2021 American Chemical Society.
52

A more in depth study on spacer length effects for a family of similar poly(N-carbazolylalkyl
acrylates) that excluded molecular weight effects potentially superimposing effects of the varied
spacer length was conducted by Thompson et al. in 2021.
110
Two poly(methyl acrylate) parent
polymers were synthesized by anionic polymerization in toluene with a n-BuLi and a PhMgBr
initiator respectively affording dyad tacticities of 74% and 87% with molecular weights of 33.4
and 13.5 kg/mol and Ð ≤ 2.0. Both polymers were then functionalized in ZnTAC24 catalyzed
transesterifications with carbazole pendant groups featuring alkyl spacers of two to twelve carbons
yielding the polymers depicted in Figure 1.8a. The post polymerization functionalization approach
used in this study ensured identical length and tacticity of the polymer backbone across each family
of functionalized poly(methyl acrylates).
UV/Vis absorption spectra for all polymers were largely identical and displayed the
characteristic peak corresponding to carbazole π–π* and n–π* transitions at 295, 330 and 344 nm.
In PL emission spectroscopy 0-0 transitions at 350 nm and a vibronic band at 368 nm were
observed for all polymers, however peaks at 405 and 430 nm corresponding to excimer emission
were only visible for spacers of up to four carbons in the 75% isotactic polymer family and up to
eight carbons in the 87% isotactic polymer family. These peaks were attributed to carbazole π–π
stacking and it was inferred that in the less isotactic polymers this stacking is only favorable for
shorter spacers while it is maintained up to significantly longer spacers in the more isotactic
polymers. Hole mobilities determined from the SCLC technique showed a clear effect of spacer
length on the charge carrier mobilities of the corresponding polymers. As depicted in Figure 1.8c,
for the less isotactic polymers μh increased when going from a two to a four carbon spacer and
then gradually declined as the spacer length increased further while in the more isotactic polymer
a six carbon spacer resulted in the highest mobility with a much more drastic decline at increased
53

spacer lengths. Annealing increased mobilities for both families of NCPEPs with a more
pronounced effect in the more isotactic polymers but did not change the observed trends in regards
to the spacer length. Both for the unannealed and annealed samples mobilities were distinctly
higher in the more isotactic polymers with μh = 2.00 × 10
-4
cm
2
/V∙s being the highest for the
annealed six carbon spacer while μh = 7.20 × 10
-5
cm
2
/V∙s was the highest for the annealed four
carbon spacer for the family of less isotactic polymers. These effects were explained through
density functional theory (DFT) computational modeling of the polymers which showed a
randomized, clumped structure for atactic polymers whereas isotactic ones showed an elongated
structure with ordered pendant units surrounding a helical backbone that becomes increasingly less
ordered as the spacer length increases. Overall, significant effects of both spacer length and
stereoregularity on the mobilities of the corresponding NCPEPs could be demonstrated.
Spacer length effects were also investigated in a study by Chen et al. for
poly(pentabutoxytriphenylenyl-oxy-alkyl acrylates) with spacers ranging from one to six carbons
(P(pBu)TP(Alk)As) depicted in Figure 1.8a.
111
The pre-functionalized monomers were
polymerized by RAFT with two distinct degrees of polymerization (DPs) of 10 and 50, the latter
affording higher molecular weight samples ranging from 10.8 to 14.8 kg/mol with Ð ≤ 1.46.
Additionally, a control polymer with the triphenylene (TP) moiety directly attached to the ester
functional group without any spacer was synthesized.
Characterization by X-ray scattering and DSC revealed no crystallization propensities
regardless of spacer length and showed wide temperature ranges for liquid crystalline (LC)
behavior from -20 °C to the isotropization temperatures at 80-180 °C. Except for the control
polymer without a spacer which behaved as a discotic mesogen-jacked LC polymer showing
absence of π–π stacking of the TP groups, all other polymers organized into ordered phases. The
54

polymers with one to four carbon spacers organized into ordered columnar phases showing glass
transition temperatures of more than 100 °C while longer spacers led to ill-defined low order
columnar phase formation and significantly reduced Tg. The DP had a significant effect on the
polymer ordering with the higher DP polymers exhibiting better assembly capability and more
ordered columnar structures and were consequently the only group of polymers investigated in
charge carrier mobility measurements. High DP polymers with a one and two carbon spacer
arranged into two-column bundles based hexagonal columnar LC (Colh, p6mm) and columnar
plastic phases (Colhp, p6mm) while three to five carbon spacer polymers exhibited three-column
bundles based on hexagonal columnar superlattice (Colh-s, p3m1), hexagonal columnar phase with
some lamellar correlation (Colh/L, p1) and supramolecular rectangular columnar plastic phase
(Colrp-s, p2mg) respectively which for the two and five carbon spacer polymers were the first
examples of side-chain discotic LC polymers showing a certain 3D positional order and similar
stacking mode of discs in pair as established for low molecular weight discotic columnar plastic
phases. Clearing temperatures were found to decrease with increasing spacer length. Optical
microscopy imaging of the samples after shearing displayed optical performances indicative of the
well-organized TP discotic polymer columns being aligned along the shearing direction with the
TP discs in edge-on orientation. Mobilities obtained by the TOF method and extrapolation to zero
electric field showed the best mobility of μ = 0.26 cm
2
/V∙s for the polymer with a one carbon
spacer, yielding roughly double the mobilities that were obtained for polymers with two, three and
four carbon spacers. At longer spacers mobility dropped significantly with μ = 0.001 cm
2
/V∙s under
a high electric field of 2.00 × 10
5
V/cm for the five carbon spacer and no detectable signal for the
six carbon spacer polymer.
55

Rather than also focusing on spacer length effects, a report by Thelakkat et al. studied effects
of extending the conjugated core of the pendant group on the properties of the resulting polymers
for two atactic liquid crystalline perylene diester side chain homopolymers, poly(perylene diester
imide acrylate) (PPDI) and poly(perylene diester benzimidazole acrylate) (PPDB).
112
Both
NCPEPs are attached to a poly(acrylate) backbone via a twelve atom spacer and have two
solubilizing ethylhexylester-side chains on the terminal end of the pendant group however PPDB
has an additional benzoimidazole moiety as an extension of the conjugated core in PPDI (Figure
1.8a). The polymer synthesis was achieved through N-tbutyl-α-isopropyl-α-phenylnitroxide
initiated NMRP of the pre-functionalized monomers in trichlorobenzene yielding PPDI with a
molecular weight of 20.4 kg/mol and Ð = 1.70 and PPDB with a molecular weight of 13.3 kg/mol
and Ð = 1.40.
Characterization of the thermotropic behavior of the polymers by DSC and polarized optical
microscopy showed a Tg of 151 °C and a reversible phase transition to an isotropic state at 312 °C
for PPDB with a small enthalpy of 3.8 J/g suggesting a phase transition from an LC mesophase to
the isotropic melt. Similarly, PPDI exhibited a Tm of 132 °C and the observed small transition
energy of 2.8 J/g indicated a LC mesophase. In X-ray diffractograms a sharper reflection peak
corresponding to π–π stacking of the perylene core of adjacent side chain could be observed for
PPDI with a stacking distance of 3.45 Å compared to 3.51 Å in PPDB. While this is indicative of
a slightly better organization and more regular packing of the perylene cores for PPDB with a more
extended conjugated pendant group, only PPDI was heated above Tm prior to these measurements
making a direct comparison challenging. UV/Vis absorption measurements of polymer thin films
showed vibronic transitions at 510, 479 and 450 nm for PPDI while the additional benzimidazole
moiety in PPDB extends the absorption to 680 nm with an absorption edge that was red-shifted by
56

almost 100 nm. Calculation of the energy levels from CV measurement revealed similar LUMO
energies of -3.52 eV for both polymers but a deeper HOMO energy of -5.68 eV for PPDI compared
to -5.39 eV for PPDB resulting in a larger band gap for PPDI. Both the lower band gap and the
bathochromic shift in the absorption spectra were explained by the increased delocalization of π-
electrons in the PPDB core through the fused benzimidazole moiety. Charge carrier mobilities
were measured via the SCLC technique with a general device structure of
glass/ITO/PEDOT:PSS/polymer/Ca/Al for electron only devices and
glass/ITO/PEDOT:PSS/polymer/Au for hole only devices. PPDB was found to be a better electron
transporting materials with μe = 3.20 × 10
-4
cm
2
/V∙s and μh = 1.00 × 10
-6
cm
2
/V∙s while PPDB was
found to be a better hole transporting material with μe = 1.90 × 10
-5
cm
2
/V∙s and μh = 1.50 × 10
-4

cm
2
/V∙s suggesting more donor-, p-type behavior for PPDI unlike the well-studied class of
NCPEPs featuring perylene bisimide pendant groups in which the presence of a second imide
.group enhances the electron-withdrawing character and renders the polymers typical n-type
materials. In PPDB on the other hand the electron deficiency in the heterocyclic aromatic system
appeared to enhance the electron-accepting properties of the material demonstrating a significant
dependance of the electronic properties of these NCPEPs on the design of the aromatic core of
their pendant groups. The polymers in this study represent the first examples of NCPEP bearing
PDB and PDI mesogens made from NMRP in literature. In a previous report on the synthesis and
characterization of PDB and PBI small molecule liquid crystals, the group had found extended
visible light absorption and mesophase formation even at room temperature however they also
observed formation of large PBI crystals unfavorably affecting blend morphologies which is a
limitation that was effectively circumvented by incorporation of PBIs as pendant groups in
NCPEPs.
113,114

57

Based on the same PerAcr pendant group Thelakkat et al. reported a family of atactic PPerAcr
for which spacer length effects were investigated and NCPEPs bearing PerAcr made from two
synthetic routes were contrasted.
115
One synthetic route followed the NMRP of trimethylsilyl
propargyl acrylate followed by silyl deprotection with TBAF and AcOH and finally
functionalization with azide-capped PerAcr in CuBr/PMDETA catalyzed azide-alkyne click
reactions affording PPerAcr-Clicks (Figure 1.8a). From two poly(trimethylsilyl propargyl
acrylates) of different molecular weights two clicked polymers, both featuring a six carbon spacer,
were obtained with molecular weights of 5.2 and 15.8 kg/mol and Ð ≤ 1.17. The other synthesis
route followed the NMRP of the PerAcr-functionalized methyl acrylate monomers and yielded the
previously reported PPerAcr with an eleven carbon spacer, PPerAcr-11C, with a molecular weight
of 18.4 kg/mol and Ð = 1.68 and PPerAcr-6C with six carbon spacer, a molecular weight of 12.5
kg/mol and Ð = 1.80. The general structures for all three types of polymers are depicted in Figure
1.8a. For a direct comparison between the two routes, a methyl acrylate monomer functionalized
with PerAcr via CuAAC was synthesized as well but polymerization failed due to the low
solubility of the monomer.
For polymer characterization only the higher Mn clicked polymer was considered to exclude
any potentially significant molecular weight effect on the respective polymer properties. In UV/Vis
absorption spectra all polymers exhibit the typical vibronic bands of PerAcr at 464, 490 and 527
nm. While the relative intensities of these bands were nearly identical in the clicked PPerAcr and
the six carbon spacer PPerAcr, the band at 490 nm gained in relative intensity for the eleven carbon
spacer PPerAcr indicating stronger aggregation of the PerAcr moieties. In DSC the eleven carbon
spacer PPerAcr showed an endothermic phase transition at 189 °C with ΔH = 7.6 J/g which was
found to be a transition from a birefringet LC state to an isotropic melt from polarized optical
58

microscopy. Additionally, temperature-dependent X-ray studies showed a decrease in sharp
reflexes beginning at 172 °C and complete isotropization at 192 °C indicative of the presence of
two different transitions. At room temperature an isotropic phase could be confirmed through X-
ray reflection corresponding to a lamellar structure and π–π stacking of the PerAcr moieties at a
mean distance of 0.347 nm. The six carbon spacer PPerAcr exhibited an endothermic phase
transition in DSC at 193 °C with ΔH = 4.6 J/g. X-ray diffraction at room temperature indicated a
lamellar 2D structure however with lower ordering than what was observed with the longer spacer
which was believed to explain the lower ΔH of the phase transition. The mean distance for PerAcr
π–π stacking was determined to be slightly increased to 0.356 nm compared to the longer spacer.
The clicked PPerAcr was found to have an endothermic phase transition in DSC at 175 °C with
ΔH = 1.2 J/g and a melting point at 288 °C overall showing thermal behavior that was similar to
that of the eleven carbon spacer PPerAcr. In X-ray diffraction the clicked polymer had less distinct
reflections with no mixed reflections between 5 and 8 nm
-1
which along with the lower ΔH suggests
a less ordered lamellar 2D structure than the two polymers from NMRP had. Overall, it was
demonstrated that post-polymerization clicked NCPEPs can maintain the same properties observed
for their counterparts made from NMRP to a significant degree. Moreover, spacer length was
demonstrated to be decisive for the phase behavior of such PPerAcr polymers with the longer
spacer enabling a higher flexibility that allows for enhances packing of the PerAcr moieties.
Triazole moieties in the spacer on the other hand were found to be quite stiff and did not lead to
increased flexibility for the PerAcr moieties. Importantly, this is the first example of a synthetic
route based on the NMRP of trimethylsilyl propargyl acrylate followed by functionalization via
CuAAC which represents a highly relevant methodology for the synthesis of families of
functionalized polymer with identical chain lengths and backbone tacticities.
59

1.2.3.2 Copolymers of poly(acrylate) NCPEPs

Moving away from poly(acrylate) derived NCPEP homopolymer systems, Sato et al.
investigated the influence of introducing varied amounts of the electroinactive n-butyl acrylate
comonomer into a poly(N-(4-acryloyloxymethylphenyl)-N′-phenyl-N,N′-bis(4- methylphenyl)-
[1,1′-biphenyl]-4,4′-diamine) (TPDac) pendant polymer and compared the resulting statistical
copolymers to a PTPDac homopolymer.
73
The stereorandom (co-)polymers shown Figure 1.9a
were synthesized from AIBN initiated radical polymerization in benzene at 60 °C of the
functionalized comonomers affording molecular weights of 2.2-4.4 kg/mol with Ð ≤ 4.0 and TPD
contents of 23% to 39% for the copolymers.
Thermal characterizations by DSC revealed decreasing Tg with increasing n-butyl acrylate
content from 150 °C for the PTPDac homopolymer to 66 °C for the copolymer with only 23 mol-
% of TPDac. Based on the absence of any melting or crystallization peak all (co-)polymers were
assumed to be amorphous. In UV/Vis absorption spectra all polymer showed nearly identical
absorption peaks at 310 and 350 nm which are characteristic for small molecule TPD. Similarly,
oxidation peaks of all polymers measured by CV were nearly identical to molecular triarylamine
and was therefore assumed to stem from a partial oxidative coupling in the TPD side chains.
Mobility measurements by the TOF method revealed mobilities in the order of μ ~ 10
-5
cm
2
/V∙s
which increased with the TPC-content for the copolymers and were about two orders of magnitude
higher than what is reported for PVK.
Effects of the ratio of pendant functionalized monomer in a copolymer was also the focus of a
study by Thelakkat et al. however their study was centered around a block-copolymer rather than
around statistical copolymers.
116
A stereorandom polystyrene-b-poly(perylene acrylates) (PS-b-
PPerAcr) block-copolymer with one electroactive block, PPerAcr, and one electroinactive block,
60

PS, was contrasted against a PPerAcr homopolymer (Figure 1.9a) synthesized from NMRP of the
pre-functionalized monomer at 125 °C. PPerAcr was obtained with a molecular weight of 30.9
kg/mol and Ð = 1.86 and the PS-b-PPerAcr block copolymer consisting of 70 wt.-% PerAcr with
a molecular weight of 37.9 kg/mol and Ð = 1.52.
In DSC traces of the copolymer features from both block were observed, a Tg at 100 °C from
the PS-block and a Tm at 189 °C from the PPerAcr-block. When used as the active material in
OEFT devices, the homopolymer and the block copolymer showed identical performance upon
annealing with electron mobilities of μe = 1.20 × 10
-3
cm
2
/V∙s but the threshold voltage of the block
copolymer at 4.1 V was lower than the 20 V in the case of the homopolymer. These results were
explained by favorable interactions of the PerAcr moieties with the substrate via annealing induced
migration of the PPerAcr-blocks to the gate oxide surface of the substrate. Scanning electron
microcopy (SEM) imaging of the block copolymers OEFT morphology showed lying cylinders
with diameters of around 15 nm and a domain spacing of 20-25 nm but due to device thicknesses
of 150 nm no conclusion could be drawn about the morphology at the bottom surface interface.
However, a maintained high charge carrier for PPerAcr could be demonstrated even upon the
incorporation of 30 wt.-% of an insulating block likely due to the pronounced stacking of bisimide
units in confined geometries.
The PPerAcr discussed in the previous section was also part of a study by Thelakkat et al. on
how polymer properties change when going from a non-electroactive polymer, in this case
polystyrene, to block co-polymers with increasing ratios of PerAcr as an electroactive pendant
block and finally arriving at a NCPEP homopolymer, PPerAcr.
117
The (co-)polymers depicted in
Figure 1.9a were made using NMRP in 1,2-dichlorobenzene from styrene and the pre-
functionalized PerAcr-monomer.
61

Figure 1.9 a) General structure of poly(acrylate) derived NCPEP copolymers. b) TEM images of
PS-b-PPerAcr 1 (a), PS-b-PPerAcr 2 (b) and PS-b-PPerAcr 3 (c); the samples were annealed for 210 °C
for 1h, embedded into epoxy resin, cut, and stained with RuO 4. Top-view SEM images of films of PS-
b-PPerAcr 1 (d), PS-b-PPerAcr 2 (e) and PS-b-PPerAcr 3 (f); the samples were annealed at 210 °C for
1h and film thicknesses were around 150 nm. c) Top-view SEM images of (g), PS:PPerAcr
homopolymer blend as cast (h) and PS:PPerAcr homopolymer blend after annealing at 210 °C for
1h (i). Reprinted with permission from Sommer et al.
117
Copyright 2008 John Wiley and Sons.
62

Three PS homopolymers with molecular weights ranging from 13.6 to 35.1 kg/mol with Ð ≤
1.14, three block-copolymers with three molecular weights, 22.3 (PS-b-PPerAcr1), 37.9 (PS-b-
PPerAcr1) and 43.1 kg/mol (PS-b-PPerAcr1), with Ð ≤ 1.78 and similar PerAcr-wt.-% of 65-70%
and finally a PPerAcr homopolymer with a molecular weight of 30.9 kg/mol and a Ð = 1.86 were
synthesized.
Characterization by DSC showed very similar Tg for both the styrene-blocks in the copolymer
and the polystyrene homopolymers of around 100 °C and Tm from the PPerAcr-block in the
copolymers at 179-192 °C, similar to the melting temperature of 193 °C in the PPerAcr
homopolymer which is indicative of microphase separation in the block copolymers. Morphology
investigations by transmission electron microscopy (TEM) and scanning electron microscopy
(SEM) of the copolymers revealed ordered structures of PPerAcr domains as shown in Figure
1.9b. The precise mode of ordering changed as the Mn of the copolymers increased from lamellar
structures to a cylindrical morphology cut horizontally and vertically and wormlike domains
among lamellar regions. π–π stacking of the PerAcr moieties for PPerAcr, the copolymer and a
blend of the two homopolymers was estimated by comparing the relative intensities of the vibronic
bands at 492 and 530 nm in the respective UV/Vis absorption spectra. Consistent with observations
from SEM, PerAcr moieties are more aggregated in the block copolymers than in either PPerAcr
or the mixture of homopolymers likely owing to the confinement in microdomains in the
copolymers while in the blend dilution of the PerAcr chromophores by the polystyrene hinders
aggregation. Thermal annealing increased the degree of aggregation across all samples. PPerAcr,
the homopolymer blend and the block copolymer of intermediate Mn were also tested as active
materials in OFET devices in bottom-gate, bottom-contact configuration. As seen with increased
aggregation after annealing, annealed devices gave better charge carrier mobilities of μ = 1.20 ×
63

10
-3
cm
2
/V∙s for both the block copolymer and the PPerAcr homopolymer and a reduced mobility
of μ = 7.90 × 10
-4
cm
2
/V∙s for the blend of polymers. This demonstrated that the more advantageous
stacking of the PerAcr moieties led to maintained high mobility even upon introduction of 30 wt.-
% of an insulating polystyrene-block. It is noteworthy that these results demonstrate a distinct
difference of NCPEP block copolymer properties compared to the established properties of CP
block copolymers, specifically those based on P3HT, for which charge carrier mobilities decrease
significantly when poly(styrene) as an electroinactive block is introduced.
118
The final study in this chapter is focused on less extended pendant systems and reverts back to
a more simplified statistical copolymer backbone structure. In 1991 Sasakawa et al. investigated
statistical copolymers of (trans-bis(9H-carbazol-9-yl)cyclobutane)methyl acrylate (ADCZB) with
either (cyano-[1,1’-biphenyl]-4-yl)oxy)undecanyl acrylate (ACB11) or methoxyphenyl-4-(2-
acryloyloxy)alkyloxy)benzoate with either a two or a six carbon alkyl spacer (APB2 and APB6)
in regards to changes in polymer properties when the content of ADCZB is increased.
119
Three
families of copolymers depicted in Figure 1.9a were made from AIBN initiated radical
polymerization of the pre-functionalized monomers in benzene at 60 °C yielding copolymers with
molecular weights of 1.0 to 2.9 kg/mol with Ð ≤ 1.70. For each of these polymer families the
ADCZB-content was varied from ~ 10 mol-% to ~ 80 mol-% in the case of the copolymers with
ACB11 and APB6 and to ~ 58% in the case of the copolymers with APB2.
Morphological characterizations by polarizing microscopy and DSC showed liquid phase
crystalline behavior only for ACB11-copolymer with an ADCZB content of up to 33 mol-% and
for the APB6-copolymer with the lowest ADCZB content while the APB2-copolymer did not show
a liquid-crystalline phase irrespective of the mole fraction of ADCZB which was explained by an
intrinsically less ordered structure when incorporating APB2 as previously seen for the respective
64

homopolymer. A molecular dispersion of the ADCZB monomeric units within the copolymers was
inferred from increases in Tg of 40-50 °C upon increasing ADCZB-content in the copolymers
which was supported by smaller changes in enthalpy and entropy associated with the Sm-I phase
transition for higher ADCZB contents since molecular moieties would act as destabilizers for the
liquid-crystalline phase. Hole drift mobilities for each type of copolymer containing around 15
mol-% of ADCZB were obtained from the TOF method with layered structures of Au/α-
Se/copolymer/SnO2-In2O3/glass. The highest mobility was measured for the ACB11-copolymer,
μ = 1.00 × 10
-5
cm
2
/V∙s, followed by the APB6-copolymer, μ = 6.80 × 10
-6
cm
2
/V∙s, and finally μ
= 5.00 × 10
-6
cm
2
/V∙s for the APB2-copolymer.

1.2.4 Poly(methacrylate) NCPEPs
1.2.4.1 Homopolymers of poly(methacrylate) NCPEPs

For a family of poly(methacrylate) derived NCPEP homopolymers, Subramanian et al.
investigated effects of extending the size of the pendant group on the resulting polymer
properties.
120
Starting from a push-pull type pendant group with a phenothiazine donor, an
oxindole π-conjugated linker and a tetrazole acceptor group (PPOTM) additional moieties were
gradually introduced on the unsubstituted side of the oxindole: at first a second phenothiazine
donor (PPOTM-D) and then a second tetrazole acceptor on that phenothiazine (PPOTM-DA)
resulting in the three NCPEPs depicted in Figure 1.10. The stereorandom polymers were
synthesized via AIBN initiated radical polymerization of the pre-functionalized monomers in THF
at 70-75 °C yielding molecular weight of 15.9-20.5 kg/mol and Ð ≤ 1.85.
65

UV/Vis absorption spectra showed an increasingly bathochromic shift of the absorption bands
with an increasing π-conjugated system of the pendant group from 448 to 469 and finally 482 nm.
Lower-energy absorption bands around 550-560 nm characteristic for intramolecular charge
transfer were red-shifted by 30 nm in PPOTM-DA which was attributed to an improved
delocalization of the π-electrons upon introduction of a second acceptor unit into the pendant
structure. HOMO-LUMO band gaps as determined from optical absorption onsets decreased with
introduction of additional moieties into the pendant group from 2.39 to 2.25 and 2.10 eV. CV
measurements of polymer films spin-coated on TiO2 revealed a decrease of the oxidation potential
upon introduction of the second acceptor moiety. Testing of the polymers as dyes in dye-sensitized
solar cells (DSSCs) showed PPOTM to give the worst performing devices with a FF value of 68
and an efficiency of 3.97%. PPOTM-D while exhibiting a slightly reduced FF value gave a higher
efficiency of 4.43% due to improved short-circuit currents and open-circuit voltages which were
attributed to increased light harvesting ability in the longer wavelength region and light-to-current
conversion efficiencies due to the introduction of the additional phenothiazine donor. The best
performance was measured for PPOTM-DA with improvements for every relevant parameter
resulting in an efficiency of 5.91% which was believed to stem from the lower band gap enhancing
electron injection from the polymer into the TiO2 and reducing the driving force for polymer dye
regeneration. According to electrochemical impedance spectroscopy (EIS) the recombination
resistance increases in order of PPOTM < PPOTM-D < PPOTM-DA indicating that PPOTM-DA
possess the most effective suppression of recombination of the injected electrons. Overall, a
significant influence of the nature of the pendant group on the properties of the respective
poly(methacrylate) NCPEP could be demonstrated.
66

Shifting focus to tuning of a different structural variable, in a 2021 study by Thompson et al.
effects of tacticity as critical design parameter on the properties of NCPEPs were investigated for
a family of poly((N-carbazolylethylthio)propyl methacrylates) (PCzETPMAs).
121

Unfunctionalized, stereoregular polymers were synthesized from DPHLi initiated living, anionic
polymerization in toluene for isotactic and in THF for syndiotactic polymers. A stereorandom
polymer was obtained from AIBN initiated RAFT polymerization. All polymers were then
functionalized with a carbazole pendant group in post-polymerization photochemical thiol-ene
reactions. The molecular weights for the final polymers depicted in Figure 1.10 were 26.1-49.4
kg/mol and Ð ≤ 2.3 with an additional syndiotactic polymer of significantly higher M n, 122.1
kg/mol with Ð = 1.20.
UV/Vis-absorption spectra showed nearly identical characteristic carbazole π–π* transitions at
295 nm and n–π* transitions at 330 and 344 nm independent of tacticity. Similarly, HOMO
energies of 5.62-5.69 eV as measured by CV showed little effect of tacticity. In PL spectra the
intensity for the 0–0 transitions at 350 nm with a vibronic band at 370 nm observed for all polymers
are higher in the isotactic and high Mn syndiotactic PCzETPMA suggesting increased aggregation
in those polymers. Upon annealing PL intensities for the same two polymers are strongly
diminished indicative of aggregation-based quenching and thus enhanced π–π stacking after
annealing, an effect that was not observed for the other PCzETPMAs. Hole mobility measurements
of unannealed samples based on the SCLC technique revealed μh ~ 10
-7
cm
2
/V∙s for the atactic and
the lower Mn syndiotactic polymer while the higher Mn syndiotactic polymer had a μh that was
higher by an order of magnitude and the isotactic PCzETPMA displayed the highest mobility of
μh = 6.00 × 10
-5
cm
2
/V∙s.
67

Figure 1.10 General structure of poly(methacrylate) derived NCPEP homopolymers.

Thermal annealing had little effect on the mobilities of the atactic and lower Mn syndiotactic
polymer but led to an increase for the isotactic polymer by about an order of magnitude. Mobilities
for the high Mn syndiotactic were shown to be the most temperature dependent with annealing at
210 °C giving the highest overall mobility of the study of μh = 1.82 × 10
-3
cm
2
/V∙s demonstrating
significant effects of both tacticity and molecular weight on the properties of this class of NCPEPs.
It is relevant to note that this study does not only confirm effects of stereoregularity on charge
carrier mobilities as discussed previously for different NCPEP architectures but additionally also
68

shows that for a given tacticity molecular weight effects on mobilities have to be considered as
well.

1.2.4.2 Copolymers of poly(methacrylate) NCPEPs from one electroactive and one
electroinactive monomer

Strohriegl et al. conducted a study on nonlinear, optically active, semirandom
poly(methacrylate) copolymers in which various azobenzene functionalized optically active
monomers were co-polymerized with the bulky 1-adamantyl methacrylate comonomer.
122

Resulting thermal properties were compared across copolymers with the four comonomers N-
methyl-4-((4-nitrophenyl)diazenyl)aniline methacrylate (MNDA-MA), N-ethyl-4-((4-
nitrophenyl)diazenyl)aniline methacrylate (ENDA-MA), N-ethyl-4-(4-((4-
nitrophenyl)diazenyl)phenyl)diazenyl)aniline methacrylate (ENDPDA-MA) and 5-((4-
(ethylamino)phenyl)diazenyl)-3-methylthiophene-2,4-dicarbonitrile methacrylate (EPDMD-
MA). MNDA-MA was connected to the methacrylate backbone via a six carbon spacer, the other
three monomers via a two carbon spacer. All four were copolymerized with 1-adamantyl
methacrylate (AdMA) in AIBN initiated radical polymerizations in chlorobenzene at 60 °C
affording the statistical copolymers PAdMA-co-P(X) depicted in Figure 1.11. With MNDA-MA
and ENDA-MA two copolymers with varied ratios of the comonomer AdMA of 83 to 66 mol-%
and 76 to 63 mol-% respectively were reported with molecular weights of 41-70 kg/mol and Ð ≤
3.10. The copolymer with ENDPDA-MA had a molecular weight of 1.2 kg/mol and Ð = 8.10 at a
mole ratio of AdMA in the polymer of 76% while the copolymer with EPDMD-MA had a
molecular weight of 3.6 kg/mol and Ð = 3.40 at a similar mole ratio of AdMA of 73%.
69

Thermal characterizations demonstrated effects of both spacer length and mole ratio of
monomeric units functionalized with optically active pendants on Tg of the resulting polymers: the
increased spacer length for the MNDA-MA copolymer led to significantly more pronounced
decreases of Tg of especially at higher ratios of functionalized pendants compared to ENDA-MA
but generally Tg decreased with introduction of any of the functionalized pendants and the decrease
was more significant at higher pendant ratios.
Block-copolymers comprised of one electroactive and one electroinactive block were also the
focus of a 2023 study by Thompson et al. on polystyrene-b-poly((N-carbazolylethylthio)propyl
methacrylates) (PS-b-PCzETPMAs) that investigated the effects of molecular weight, relative
ratio of the two blocks and tacticity of the pendant functionalized block on the properties of the
resulting NCPEP-copolymers.
123
Two sets of block copolymers were reported, one with lower
molecular weights of 3.31-10.13 kg/mol and Ð ≤ 1.58 and one with higher molecular weights of
16.6-37.3 kg/mol and Ð ≤ 1.31. For each set block ratios were varied to give copolymers with
dominant PS blocks and polymers with dominant PCzETPMA blocks and additionally tacticities
of the pendant block were varied to give isotactic and atactic PCzETPMA blocks in both sets
(Figure 1.11). All polymers were synthesized by anionic living polymerization of styrene and the
unfunctionalized monomer allyl-methacrylate with n-BuLi in toluene for polymers with isotactic
poly(allyl-methacrylate) (PAMA) blocks and in toluene/THF mixtures for atactic PAMA blocks.
The PAMA blocks were then functionalized with carbazole pendant groups in post-polymerization
photochemical thiol-ene reactions.
UV/Vis absorption spectra were nearly identical for all copolymers showing carbazole π–π*
transitions around 295 nm that coincide with bands from intramolecular excimer induced
absorption in the PS-blocks as well as carbazole n–π* transitions at 330 and 344 nm. PL
70

spectroscopy revealed carbazole 0-0 transitions at 350 nm and a vibronic band at 370 nm while
excimer emission peaks around 405-420 nm were absent indicating a limited degree of π-stacking
of the PCzETPMA pendant groups. Upon annealing PL intensities are reduced for all polymers
suggesting aggregation based quenching that was explained by a more pronounced π–π stacking
of the pendant group. Hole mobilities for as cast and annealed samples were measured via the
SCLC method but did not show any significant trends for the family of lower Mn copolymers and
exhibited low mobilities of μh ~ 10
-6
-10
-7
cm
2
/V∙s which was believed to stem from the overall low
molecular weights. For the family of higher Mn however distinct trends could be observed
specifically for the annealed samples which exhibited higher hole mobilities than the unannealed
ones. Regardless of which block was dominant in the copolymers, the polymers with an isotactic
PCzETPMA block outperformed their atactic analogues. This effect was more pronounced when
PCzETPMA also made up the dominant block in the copolymers with the high Mn PS-b-
PCzETPMA with an isotactic, dominant PCzETPMA exhibiting the highest mobility of μh = 2.33
× 10
-5
cm
2
/V∙s after annealing. Overall, distinct effects of molecular weight, tacticity and block
ratio on the resulting charge carrier mobilities could be demonstrated for this class of NCPEP
block-copolymers. This report demonstrated for the first time that structure property relationships
previously established for NCPEP homopolymers such as increased charge carrier mobilities in
more stereoregular polymers can also hold true in more complex NCPEP architectures such as
block copolymers.
71

Figure 1.11 Chemical structures of poly(methacrylate) derived copolymers with one
electroinactive comonomer and of PMEMA-co-P(Y)s exclusively featuring electroactive monomers.

72

1.2.4.3 Copolymers of poly(methacrylate) NCPEPs from electroactive monomers

In addition to their aforementioned study, Strohriegl et al. introduced a second family of
random copolymers bearing exclusively electroactive monomers in addition to revisiting the
polymers shown in Figure 1.11 that were discussed previously.
124
This second family consists of
statistical copolymers of 2-(methacryloyloxy)ethyl-3-(5-methylfuranyl)acrylate (MEMA) with the
previously introduced optically active comonomers ENDA-MA or EPDMD-MA. The
stereorandom copolymers PMEMA-co-P(Y) shown in Figure 1.11 were synthesized from AIBN
initiated radical polymerization at 60 °C affording molecular weights of 1.2 kg/mol with Ð = 2.20
for the ENDA-MA copolymer and 4.3 kg/mol with Ð = 2.20 for the EDPMD-MA copolymer, both
with MEMA mole ratios of around 68%. The polymers in the family mentioned for the previous
study gave very similar molecular weights and mole ratio of the AdMA comonomer as discussed
before with the exception of AdMA-co-EDPMD-MA which had a significantly higher molecular
weight of 12.6 kg/mol reported for this study at a Ð = 1.80 and a AdMA mole ratio of 61%.
Thermal characterization comparing the two families of copolymers revealed significantly
lower Tg for the MEMA-containing copolymers of < 100 °C compared to > 165 °C for the AdMA-
containing copolymers with the same spacer length. UV/Vis absorption measurements of the
MEMA copolymers during crosslinking of the MEMA groups showed absorption maxima
stemming from the photocrosslinkeable MEMAs at 320 nm and from the chromophore
comonomer at 480 nm for the ENDA moiety and 550 nm for the EDPMD moiety. The MEMA
peak decreased over time as the number of cross-linked moieties increased while in the case of
ENDA the chromophore absorption peak also strongly decreased due to cis-trans isomerization of
the azo dye with the cis isomer exhibiting a much lower molecular hyperpolarizability. For the
73

EDPMD chromophore no such decrease was observed which was attributed to the steric effects of
the methyl groups in the thiophene preventing efficient cis-trans isomerization.
Continuing with a poly(methacrylate) random copolymer structure but switching to thiophene,
carbazole and fluorene pendant groups, changes in morphology and supramolecular self-assembly
and of optical properties upon incorporation of these various pendant groups were investigated by
Valiyaveettil et al.
125
The pendant groups in this study were thiophene with a two carbon spacer,
fluorene with no spacer and carbazole with a two carbon, an eleven carbon and a diethoxy-propyl
spacer. For synthesis of the four atactic statistical copolymers depicted in Figure 1.12 the
respective functionalized methacrylate derived monomers, carbazolyl-ethyl methacrylate
(CzEMA), fluorenyl methacrylate (FlMA), carbazolydecyl methacrylate (CzDMA), thiophenyl-
ethyl methacrylate (ThEMA) and carbazolyl-ethoxy-ethoxy-ethyl methacrylate (CzEEEMA),
were polymerized radically in toluene at 60 °C with AIBN as the initiator. The molecular weights
of the copolymers were ranging from 5.5 to 20.2 kg/mol with Ð ≤ 1.67 however ratios of the
different monomeric units in the copolymers were not measured.
Glass transition temperature measured by DSC ranged from 82-116 °C with longer spacers
leading to lower Tg and consequently ThEMA-co-FlMA having the highest Tg. UV/Vis-absorption
spectra of the copolymers showed the same bands observed for blends of homopolymers with the
respective chromophore groups suggesting that there is no interaction between the different
chromophores in their ground state. In fluorescence spectroscopy however lower fluorescence
intensity for the copolymers were observed compared to homopolymers of the same chromophore
concentration. Compared to CzEMA-co-CzEEEMA only containing carbazole chromophores
introduction of other functional moieties red shifted the emission maxima.
74

Figure 1.12 Chemical structures of poly(methacrylate) derived copolymers exclusively containing
electroactive comonomers.

Potential formation of solvent-dependent supramolecular self-assembly of the polymers was
investigated by TEM but only CzEMA-co-FlMA displayed an ordered arrangement of 1D hollow
tubes via chain aggregation through π–π stacking of side chain pendant groups.
Unlike all of the discussed examples of NCPEPs which were exclusively covalently bound
systems, a 2009 study Lin et al. relied on supramolecular assembly within NCPEPs by
synthesizing homo- and copolymers bearing pyridyl pendant groups that can act as acceptors for
hydrogen bonding and could assemble with small molecule dyes bearing terminal cynoacrylic acid
that can act as donor for hydrogen bonding.
126
Two atactic polymers, a pyridyl pendant
homopolymer and a statistical copolymer of pyridyl pendant and ethylcarbazole functionalized
methacrylate with equal mole ratios of both comonomers, were synthesized via AIBN initiated
75

radical polymerization in THF at 60 °C as the H-acceptors materials. The molecular weights were
14.4 kg/mol with Ð = 1.72 for the homopolymer and 38.1 kg/mol with Ð = 3.24 for the copolymer.
The four small molecule H-donors were (E)-2-cyano-3-(5'-(7-(4-(diphenylamino)phenyl)-9,9-
dihexyl-9H-fluoren-2-yl)-[2,2'-bithiophen]-5-yl)acrylic acid (S1), (E)-2-cyano-3-(5'-(7-(9-ethyl-
9H-carbazol-3-yl)-9,9-dihexyl-9H-fluoren-2-yl)-[2,2'-bithiophen]-5-yl)acrylic acid (S2), (E)-2-
cyano-3-(5'-(5'-(4-(diphenylamino)phenyl)-4,4'-dihexyl-[2,2'-bithiazol]-5-yl)-[2,2'-bithiophen]-5-
yl)acrylic acid (S3) and (E)-2-cyano-3-(5'-(5'-(9-ethyl-9H-carbazol-3-yl)-4,4'-dihexyl-[2,2'-
bithiazol]-5-yl)-[2,2'-bithiophen]-5-yl)acrylic acid (S4) as depicted in Figure 1.12 along with the
polymer structures.
The supramolecular assemblies were formed by slow evaporation of the solvent of solutions
in THF containing equimolar amounts of pyridyl pendant units on the polymer and acid units on
the respective dye. Successful assembly formation was confirmed through changes of the C=O
and O-H stretches of the carboxylic acid groups in FT-IR. In thermal characterizations by DSC
increased Tg in the supramolecularly bonded polymer in comparison to the neat polymers were
observed which were explained by the additional π–π interactions between the hydrogen bonded
donor dyes with the more rigid bithiazole based dyes S3 and S4 having a more significant effect
on Tg. The copolymer complexes had overall higher Tg than the homopolymer complexes due to
the presence of the bulkier and rigid carbazole comonomer. X-ray diffraction measurements found
nematic phase morphologies for the homopolymers but mesophases for the copolymers could not
be observed indicating that the nonmesomorphic carbazole monomeric units dilute and hinder the
molecular packing of the liquid crystalline moieties. In the hydrogen bonded complexes of the
copolymer however nematic phases were observed. UV/Vis-absorption spectroscopy showed a
distinct blue-shift of the absorption maxima of the polymers at 385 and 393 nm and of the dyes in
76

the range of 458-462 nm upon formation of the supramolecular assembly. Bithiazole-linked dyes
(S3 and S4) and their corresponding assemblies had longer absorption wavelengths than their
fluorene-linked counterparts (S1 and S2) and consequently also lower optical band gaps. Emission
spectra as determined from PL spectroscopy were blue-shifted as well and emission intensities of
the polymers were drastically reduced upon the formation of the hydrogen-bonded assemblies.
Band gaps calculated from CV measurements were reduced by about 0.5 eV in the assemblies
relative to the neat polymers however the bands were wider which was explained by dilution
effects upon introduction of the dyes into the polymers. Finally, the assemblies were tested
alongside a fullerene acceptor as the active layer in ITP/PEDOT:PSS/supramolecular polymer
assembly : PCBM (1:1 weigh ratio)/Ca/Al solar cell devices. With the exception of the two lowest
efficiency devices based on the copolymer with S2 and S4 which gave overall efficiencies of
0.06% and 0.07% respectively and the best performing device based on the homopolymer with S3
giving the highest JSC = 3.17 mA/cm
2
and FF value of 34 resulting in an efficiency of 0.50%, all
other devices exhibited similar device characteristics with efficiencies ranging from 0.13 to 0.32%.
Generally, the copolymer devices performed worse which was reasoned to stem from a reduced
dye content for the same weight. Triphenylamine end-capped dyes (S1 and S3) gave better
efficiencies than carbazole-capped dyes (S2 and S4) which was believed to result from enhanced
aggregation of carbazole-capped dyes. Overall, the study was able to demonstrate successful
formation of hydrogen-bonded supramolecular assemblies of NCPEPs with small molecules and
showcase a distinct effect of the structures of these small molecules on the properties of the
resulting supramolecular polymeric assembly. It is worth noting that despite showcasing the
synthetic route towards a unique subclass of NCPEPs this report is the first time specific structure
property relationships were studied in supramolecularly assembled NCPEPs.
77

1.2.5 Poly(norbornene) NCPEPs

In a 2004 study by Marder et al. effects of different backbone structures on NCPEP polymer
properties were investigated by synthesizing a poly(norbene) and a poly(methacrylate) both
bearing the same 2,7-(diarylamino)fluorene pendant group.
127
Synthesis of the stereorandom
poly(methacrylate) was realized through AIBN initiated radical polymerization of the
functionalized monomer, (2,7-Bis(phenyl-m’-tolylamino)-9-[3-(methacryloyloxy)propyl]-9-
methylfluorene)methacrylate (BPMMMA) shown in Figure 1.10, in benzene at 60 °C and yielded
a molecular weight of 17.0 kg/mol and Ð = 3.50. The norbornene functionalized monomer, (2,7-
Bis(phenyl-m’-tolylamino)-9-[3-(methacryloyloxy)propyl]-9-methylfluorene)norbornene
(BPMMN), was synthesized through a [Ru(PCy3)2(=CHPh)Cl2] catalyzed ROMP in DCM at room
temperature affording an atactic polymer with a molecular weight of 13.0 kg/mol and Ð = 1.30.
Additionally, the norbornene monomer was copolymerized with methyl 4-[(5-norbornen-2-
yl)methoxy]cinnamate (MNMC) in a 7:3 ratio in a ROMP catalyzed by [RuL(PCy3)(=CHPh)Cl2]
(L = 1,3-bis(mesityl)-2-imidazolidinylidene) in DCM at room temperature. The structure of the
respective random copolymer as well as the two homopolymers is depicted in Figure 1.13a.
Thermal characterizations by DSC showed a Tg of 97 °C for poly(BPMMN) and of 120 °C for
poly(BPMMN -co-MNMC). Crosslinking of the copolymer was followed by UV/Vis-
spectroscopy which revealed a decrease of the absorbance at 310 nm associated with the cinnamate
group while the absorbance at 377 nm associated with the bis(diarylamino)fluorene moiety
remained constant suggesting that crosslinking occurs exclusively between the cinnamate groups
without causing degradation of the bis(diarylamino)fluorene pendants.
78

Figure 1.13 a) Chemical structures of poly(norbene) derived NCPEPs. b) Electric-field
dependence of the hole mobilities of PBPMMA (diamonds) and PBPMMN (triangles) measured as a
function of electric field at 299 K; symbols represent experimental data, lines are linear fits according
to the disorder formalism. Reprinted with permission from Hreha et al.
127
Copyright 2004 Elsevier
Ltd.

79

Mobility measurements via the TOF method at different electric fields for the homopolymers
plotted in Figure 1.13b demonstrated a superior hole mobility μh ~ 10
-4
cm
2
/V∙s for the norbornene
derived polymer which was around three times the mobility measured for the methacrylate derived
polymer. This was explained by reduction of the energetic disorder due to a less polar backbone
in the case of the norbornene derived polymer. This report highlights how despite not being part
of the conjugated systems for charge carrier transport confined to the pendant groups, NCPEP
backbone architectures can have a distinct effect on electronic properties such as charge carrier
mobilities as well.
ROMP was also the synthetic route of choice for norbornene derivatives bearing a pendant
phenyl- or thiophene-capped quarterthiophene core on the side chains for which Ng et al.
investigated the effect of these different substituents on the core on the properties of the respective
poly(norbornene) NCPEPs.
128
The polymerizations of the respective functionalized monomers,
phenyl- and thiophene-capped bicyclo[2.2.1]hept-5-ene-2,3-diylbis(methylene) bis(7-
(quaterthiophen-3''-yl)heptanoate) (PHDBThHep), were catalyzed by
bis(tricyclohexylphosphine)benzylidine ruthenium(IV) dichloride and carried out in refluxing
DCM affording the two polymers depicted in Figure 1.13a. For the phenyl-capped polymer a
molecular weight of 1.50 kg/mol and Ð = 1.21 was achieved and for the thiophene-capped
analogue a molecular weight of 3.30 kg/mol and Ð = 1.23.
As determined from characterization via DSC, the phenyl-capped polymer had a higher Tg of
83.1 °C compared to 71.7 °C for the thiophene-capped polymer. In UV/Vis absorption the
absorption maximum for the thiophene-capped polymer at 432 nm was virtually identical to the
respective monomer while the phenyl-capped polymer displayed a slight blue-shift relative to the
respective monomer with a maximum at 421 nm. In PL emission spectra however both polymers
80

exhibited a red-shift relative to their monomers which was attributed to slightly increased π–π
stacking interactions in the polymers. Redox properties of the polymers were investigated by CV
which revealed two quasi-reversible oxidation processes for the phenyl-capped polymer but only
significant anodic peak for the thiophene-capped one which was found to stem from cross-linking
of the terminal thiophenes demonstrating a superior electrochemical stability of the phenyl-capped
polymer. Additionally, the phenyl-capped polymer showed a fairly reversible p-doping/dedoping
process while the doping of the thiophene-capped polymer was virtually irreversible. Finally, the
polymers were tested in single-layer photovoltaic devices with the general architecture
Al/polymer/PEDOT:PSS/ITO. While the overall device efficiencies were rather low, repeated
measurement of the device performance over time showed a significantly better stability of the
phenyl-capped devices which stabilized after the initial illumination unlike the thiophene-capped
ones which showed a much faster and continuous decay in performance. Overall, a distinct effect
of the pendant group structure on the stability of the resulting NCPEP could be demonstrated.
Rather than also polymerizing norbornene derived pendant monomers via ROMP, Do et al.
reported a vinyl-type polymerization yielding a poly(norbornene) based NCPEP.
129
The non-
electroactive monomer 6-(bicyclo[2.2.1]hept-5-en-2-yl)octyl 2-ethylhexanoate (BHOE) was
copolymerized with the PCBM functionalized, electroactive monomer 7-(bicyclo[2.2.1]hept-5-en-
2-yl)octyl 5-phenylpentanoate (PCBM-BHOP) to afford the atactic random copolymers
P(PCBM)BHOP-co-PBHOE depicted in Figure 1.13a. For the polymerizations an activated
catalyst solution from [(NHC)Pd( η
3
-allyl)Cl] and Li[B(C6F5)4 ·2.5Et2O] in chlorobenzene was
prepared which was then filtered and added to solutions of the monomers and the chain-transfer
agent 1-octene in chlorobenzene at 25 °C. Homopolymers of PCBM-BHOP were insoluble in all
common organic solvents but a homopolymer of BHOE was obtained with a molecular weight of
81

0.9 kg/mol and Ð = 1.70. Two copolymers were reported with varied PCBM-BHOP ratios of 62%
and 50% and molecular weights of 0.9 kg/mol with a Ð of 1.62 and 12.1 kg/mol with a Ð of 1.39
respectively.
In DSC measurements no apparent glass transition was observed for the copolymers indicating
amorphous morphologies. The UV/Vis-absorption spectra of the copolymer with the higher
PCBM-BHOP ratio was found to be virtually identical to that of the respective norbornene
monomer with a small shoulder at 700 nm corresponding to [6,6] addition in the C60 moiety and a
broad absorption band at 480 nm which is blue-shifted to neat PCBM consistent with reports on
similar higher alkyl ester derivatives of PCBM. The LUMO level of the copolymer as determined
from CV measurements was -3.67 eV which was also nearly identical to the LUMO of the PCBM-
BHOP monomer at -3.69 eV indicative of a negligible influence of the polynorbornene backbone
on the electronic properties of the copolymer. The copolymer was then tested as the acceptor
material alongside P3HT as a donor in OPV devices of the general structure
ITO/PEDOT:PSS/copolymer:P3HT/Ca/Al. The best performance was reported for a
donor:acceptor ratio of 1:0.45 by weight which gave a FF value of 54 and a device efficiency of
1.50% which about half the efficiency that was reported for a PCBM/P3HT device with a
donor:acceptor ratio of 1:0.7.

1.3 Conclusion

Selected, relevant studies on structure–property relationships in NCPEPs showcasing the
current state of the literature in this field have been presented. NCPEP homopolymers, random-
and block copolymers have been considered based on five general polymer backbone architectures,
82

poly(vinyls), poly(styrenes), poly(acrylates), poly(methacrylates) and poly(norbornenes). Optical,
electronic and physical properties of these polymers were demonstrated to be dependent on tunable
structural variables such as polymer backbone, length of the spacer, the structure of the pendant
group, molecular weight and in the case of copolymers ratios between the various comonomers
and individual polymer blocks by the reports in this review.
Improved charge carrier mobilities for higher degrees of backbone stereoregularity were
reported across poly(vinyl), poly(acrylate) and poly(methacrylate) NCPEP homopolymer. A
similar effect was observed for excimer emission in the PL spectra of poly(vinyl) and poly(styrene)
NCPEP, particularly with carbazole as the pendant group, which increased in intensity with higher
degrees of stereoregularity. Independent of the polymer backbone significant effects of tuning the
pendant group structure were demonstrated with generally improved charge carrier mobilities for
more extended pendants as well as shifted emission and absorption behavior of the polymers.
Aside from increasing the size of the pendant group, structural tuning via synthesis of isomeric
pendants and different end-capping units for the same pendant core were shown to affect mobility
and stability as well. For both poly(styrene) and poly(acrylate) NCPEPs effects of varied spacer
lengths were discussed with an increase in spacer length initially improving physical and electronic
properties before decreasing them once an optimal length is exceeded. In studies on poly(styrene)
derived NCPEP copolymers gradual changes in absorption and emission behavior based on the
comonomer ratios in the polymer were observed which, similar to poly(acrylate) and
poly(methacrylate) copolymers, also affected the microphase morphologies of the copolymers. In
poly(styrene) block-copolymers these morphologies were also depending on the molecular
weights of the block copolymers while charge carrier mobilities for the same polymers were
largely independent of molecular weight, unlike what was reported for poly(methacrylate) block-
83

copolymers which exhibited significantly enhanced mobilities with higher molecular weights as
well as with higher degrees of stereoregularity, consistent with the finding for the respective
poly(methacrylate) homopolymers. For poly(methacrylate) and poly(acrylate) block-copolymers
with an electroinactive polystyrene-block, high charge carrier mobilities for poly-styrene contents
of up to 45% and 30% respectively were maintained. For a poly(norbene) NCPEP homopolymer
improved charge carrier mobilities over the analogous poly(methacrylate) polymer with the same
spacer and pendant group and nearly identical molecular weight were demonstrated.
While this review is not intended to serve as a comprehensive summary of all studies on
structural tuning of NCPEPs, the selected studies highlight the relevancy of understanding how
polymer properties are impacted by these fundamental structural parameters for the rational design
of novel NCPEPs for targeted applications in the future.
We believe that based on the established structure-property relationships discussed here, this
review can serve as a guideline for such targeted design of NCPEPs.
Based on the promising results achieved with NCPEP systems to date and the enormous
potential associated with them especially in light of the limitations that current conjugated organic
systems still suffer from, the field of NCPEPs can be expected to expand rapidly over the next
decades with the literature on fundamental structure–property relationships for these polymers
growing substantially as well. Reviews like the one at hand can serve as an important tool for
polymer design in this process and we are excited to see where continued research efforts will lead
this promising field.

84

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95

Chapter 2: Synthesis of Block Copolymers Containing Stereoregular Pendant
Electroactive Blocks

2.1 Introduction
Conjugated polymers (CPs) are gaining increasing attention for use in applications such as
organic field effect transistors (OFETs),
1
organic photovoltaics (OPVs),
2,3
organic light-emitting
diodes (OLEDs),
4
electrochromics,
5
and bioelectronics owing to their electrochemical, optical, and
semiconducting properties.
6
They offer significant advantages over their inorganic counterparts
including light weight, flexibility, low cost, biocompatibility, and easy roll-to-roll processing.
7,8

Despite great advances, CPs still suffer from critical limitations, namely, poor mechanical
properties,
9
low environmental stability,
10
low molar masses,
11
and limited synthetic
methodologies, that generally do not allow access to more complex architectures such as block
copolymers.
12
In recent years nonconjugated pendant electroactive polymers (NCPEPs) have
gained interest for providing promise to overcome the limitations of CPs. NCPEPs are based on a
nonconjugated backbone with electroactive, pendant groups that connect to the backbone through
a spacer of fixed length and nature. We note that poly-(dibenzofulvene) and derivatives represent
highly π-stacked nonconjugated polymers, albeit with limited molar mass and solubility.
13
While
charge carrier mobilities for NCPEPs are typically orders of magnitude lower than for CPs,
14
recent
work in our group has demonstrated that optimizing parameters such as the spacer length and the
stereoregularity of the backbone can significantly increase hole mobilities, even outperforming the
well-established CP poly(3-hexylthiophene) (P3HT).
15−17
The impact of stereoregularity on
mobility in NCPEPs is analogous to the impact of regioregularity and structural regularity in
general on the properties of conjugated polymers.
18,19
Past work, most notably by Thelakkat et al.,
96

has further shown that hierarchically ordered structures, namely, block copolymers, can be realized
with NCPEPs through synthetic methodologies incompatible with traditional CPs.
20
While those
block copolymers did not have stereoregular backbones and gave low efficiencies in OPV devices,
they demonstrated a path for accessing more advanced polymer architectures. Here we report for
the first time a family of block copolymers in which one block is a stereoregular NCPEP.
Poly(styrene)-b-poly(allyl methacrylate) polymers (PS-b-PAMA) with both atactic and isotactic
PAMA-blocks were synthesized via living anionic polymerization, and the PAMA-block was
functionalized with carbazole as the electroactive pendant group through postpolymerization
functionalization. We were able to show that significant hole mobility (μh) is maintained in the
functionalized block copolymers despite the introduction of an insulating PS-block and that the
stereoregularity as well as the relative ratio of the electroactive PAMA-block in the copolymer
heavily impacts μh. This study showcases that complex polymer architectures with controlled
tacticities can be realized with NCPEPs and demonstrates that desired properties such as hole
mobility are maintained. For this study, block copolymers with one electroinactive block, atactic
PS, and one electroactive block, poly((N-carbazolylethylthio) propyl methacrylate) (PCzETPMA),
were chosen to study how electronic properties, namely μh, change when transitioning from
PCzETPMA homopolymers to block copolymers where PCzETPMA is now only making up one
of the blocks as schematically shown in Figure 2.1.
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Figure 2.1 Increasing complexity of NCPEP architecture when transitioning from linear
homopolymers to block-copolymers.

2.2 Experimental
PAMA functionalized with N-carbazolylethanethiol was chosen as the electroactive block for
consistency with our study on analogous NCPEP homopolymers.
15
The carbazole pendant groups
are attached via a six-atom spacer based on our previous study on isotactic poly(N-carbazolylalkyl
acrylates) reporting a six-atom spacer to give the highest μh.
16
Introduction of the pendant group
was achieved via postpolymerization functionalization of the PAMA-block in photochemical
thiol−ene reactions.
21
PS was chosen for the electroinactive block because of its well-established
98

synthetic procedures in block copolymers and the extensive characterization of PS (block-(co-))
polymers available in the literature.
22,23
The PS-b-PAMA polymer family was synthesized via
living anionic polymerization using n-BuLi as the initiator (Scheme 2.1). Since the PS-block was
meant to be atactic, higher reaction temperatures could be used than what was required for the
synthesis of the stereoregular PAMA-blocks which aids in ensuring full conversion of styrene prior
to addition of allyl methacrylate. Therefore, PS was chosen as the first block. Moreover, for PS,
the presence of living chains can be verified through a distinct orange coloration so that it was
synthetically more practical to verify the successful initiation of the PS polymerization and its
transfer onto the second block. The synthesis of the PS-block was based on previous work by Hall
et al. which found formation of a styrene macroinitiator from the alkyl lithium with a few drops of
styrene to be a critical step. Once the development of maximum color indicated the complete
conversion of alkyl lithium to styryl anions (instantaneous in THF/toluene and after ∼45 min in
toluene) the remaining styrene was added dropwise.
24
Molar mass and Đ for the PS-blocks (via
aliquots) and detailed reaction conditions for all copolymers can be found in Appendix A.

Scheme 2.1 General synthesis of block copolymers PS-b-PAMA and their functionalization with
N-Carbazolylethanethioate to give PS-b-PCzETPMA.

Synthesis of the PAMA-blocks was guided by our previous findings for stereoregular PAMA
homopolymers showing that anionic polymerization in toluene at low temperatures yields highly
99

isotactic PAMA as well as work by Brownstein et al. demonstrating that addition of as little as 2.5
vol % THF to the toluene leads to atactic PAMA.
15,25
Using these methods, we synthesized nine
PS-b-PAMA block copolymers indicated as B1u−B9u (Table 2.1), where the subscript u indicates
an unfunctionalized PAMA block. Here, we varied the molar mass, the tacticity of the PAMA-
block, and the relative ratio of the PS- and PAMA-blocks. As listed in Table 2.1, B1u−B4u are
copolymers with lower molar masses ranging from 2.36 to 7.82 kg/mol, while copolymers
B5u−B9u range from 15.61 to 41.82 kg/mol. Table 2.1 also lists the block ratios for each copolymer
as determined by
1
H-NMR. Additionally, the tacticity of the PAMA-blocks was controlled to give
both isotactic and atactic blocks with the triad tacticities also listed in Table 2.1.
Triad tacticities were determined from
1
H-NMR according to our previously published method
for PAMA homopolymers.
15
The PS-b-PAMA copolymers, B1u−B9u, were reacted with N-
carbazolylethanthioate under UV irradiation (λ = 300 nm) in the presence of the photoinitiator 2,2-
dimethoxy-2-phenylacetophenone (DMPA), affording the functionalized block copolymers PS-b-
PCzETPMA, B1f −B9f, following our previously established postpolymerization functionalization
procedure.
15
For B1f −B9f the subscript f indicates functionalized copolymers. For the thiol−ene
reaction either 1,2-dichlorobenzene or toluene was used as the reaction solvent. The choice of
solvent was dictated by the solubilities of the unfunctionalized block copolymers B1u−B9u. As
summarized in Table 2.1, this yielded polymers with ≥94% functionalization of the PAMA-blocks
for eight out of the nine polymers. In the
1
H-NMR spectra, functionalization can be followed via
the disappearance of the characteristic alkene PAMA-peaks and the appearance of the aromatic
peaks of the carbazole pendant group and the aliphatic spacer peaks.

100

Table 2.1 Molecular Weights, Polydispersities, Polymer Yields/Conversions, Triad Tacticities
and PS-to-PAMA Block Ratios for the Family of PS-b-PCzETPMA Polymers.
Copolymer Mn [kg/mol] Đ Yield [%]
Triad Tacticity [%]
(mm/mr/rr)
PS:PAMA
B1 u 3.08 1.18 70
a
15/32/53 1.75:1
B2 u 2.36 1.40 68
a
28/35/37 1:1.26
B3 u 4.48 1.18 57
a
88/8/4 1.96:1
B4 u 7.82 1.27 71
a
83/12/6 1:1.27
B5 u 15.61 1.14 74
a
17/23/60 1.53:1
B6 u 15.98 1.19 32
a
11/30/59 1.11:1
B7 u 41.82 1.14 41
a
83/10/7 3.58:1
B8 u 25.93 1.24 59
a
183/13/4 1.88:1
B9 u 27.55 1.21 22
a
80/311/9 1:1.22
B1 f 3.31 1.12 >99
b
15/32/53 1.75:1
B2 f 3.43 1.48 94
b
28/35/37 1:1.26
B3 f 4.56 1.18 >99
b
88/8/4 1.96:1
B4 f 10.13 1.30 >99
b
83/12/6 1:1.27
B5 f 16.62 1.10 97
b
17/23/60 1.53:1
B6 f 19.38 1.31 90
b
11/30/59 1.11:1
B7 f 37.27 1.27 94
b
83/10/7 3.58:1
B8 f 19.96 1.25 96
b
183/13/4 1.88:1
B9 f 28.17 1.22 >99
b
80/311/9 1:1.22
a
Isolated polymerization yields after purification.
b
Thiol–ene conversions as determined from
1
H-NMR.
After functionalization with the thiol−ene reaction, all polymers were precipitated in methanol,
dried, and characterized by
1
H-NMR (see Appendix A). The absence of sharp aromatic peaks
corresponding to unreacted molecular N-carbazolylethanthioate indicated the effective removal of
the molecular species in all cases except for B3f, where residual molecular species are likely still
present (Figure A.14). This is consistent with our reported results for the functionalization of
101

PAMA homopolymers.
15
While B1u−B4u copolymers with either a dominant PS or a dominant
PAMA block were synthesized, it proved more difficult to realize copolymers with a dominant
PAMA block in the higher molar mass range, especially under conditions required for atactic
PAMA. Therefore, PS is the dominant block in B5u and B6u; however, the relative ratio of the
blocks was varied to range from a clearly dominant PS-block to two blocks of roughly the same
length with B6u. In both B7u and B8u isotactic PAMA is the shorter block, but B7u has a
significantly more dominant PS-block. For B9u, a dominant isotactic PAMA-block was achieved.
The successful formation of block copolymers was confirmed through
1
H-NMR and gel
permeation chromatography (GPC) of aliquots of the PS-blocks and the final copolymers as well
as additional control studies (vide infra). The
1
H-NMR spectra confirm the presence of styrene and
allyl methacrylate blocks. GPC traces, which are shown in Appendix A, were used to verify the
synthesis of true covalently linked block copolymers rather than mixtures of homopolymers.
Specifically, for each copolymer, GPC traces of the PS-aliquot show one single peak with a
positive refractive index (RI) and a very narrow Đ of ∼1.20 indicative of a living polymerization.
After growth of the second block, the GPC traces show a wave-shaped pattern with a negative RI
associated with the PAMA block (which is consistent with previous studies on PAMA
homopolymers) that immediately transitions into the PS-peak with a positive RI without leveling
out on the baseline in between.
15
After functionalization of the PAMA-block, the copolymers show
just one peak with a positive RI at a shifted molar mass compared to the PS-peak. As an additional
control study, described in depth in Appendix A, we synthesized both PS and PAMA
homopolymers and made a physical mixture of the two which was stirred in boiling acetone, which
is known to dissolve lower molar mass PS.
26−28
After filtering the solution, we found PS and small
amounts of PAMA in the filtrate, whereas the filtered off solids were exclusively comprised of
102

PAMA. The same experiment with the block copolymer B9u gave no polymer in the filtrate and
showed the same
1
H-NMR and GPC trace for the filtered-off solids as before (Appendix A).

2.3 Results and Discussion
All PS-b-PAMA (B1u−B9u) and PS-b-PCzETPMA (B1f − B9f) polymers were characterized
via differential scanning calorimetry (DSC). While no significant features could be observed for
the unfunctionalized copolymers or the lower molar mass functionalized polymers (B1 f −B4f),
endothermic peaks around 75 and 100 °C, respectively, can be observed in the first cycles for B5f
−B9f which disappear in the second cycles. These transitions are believed to stem from smectic
liquid crystalline phase transitions which are known to occur within this temperature range for PS-
block-copolymers bearing liquid crystal side chains.
29
Carbazole is established to induce liquid
crystalline behavior.
30,31
No melt or crystallization transitions were observed for any copolymers.
The functionalized copolymers, both unannealed and annealed at 150 °C for 30 min, were further
analyzed by thin-film UV−vis absorption, showing little to no differences across the family of
copolymers (Appendix A), and did not show any change in features after annealing. For all
functionalized samples characteristic π−π* transitions around 295 nm and n−π* transitions around
330 and 344 nm for the carbazole pendant group were observed which is consistent with what is
observed for PCzETPMA homopolymers. PS homopolymers are known to exhibit an absorption
band around 290 nm ascribed to the formation of intramolecular excimers. Consequently,
absorption bands stemming from the PS-block in the copolymers are expected to largely coincide
with the carbazole π−π* transition.
32−34
Additionally, photoluminescence (PL) spectra for all
annealed and unannealed functionalized copolymers were measured. The spectra for the high
molar mass polymers (B5f −B9f) are shown before annealing in Figure 2.2a and after annealing at
150 °C for 30 min in Figure 2.2b. For all samples characteristic carbazole 0−0 transitions at 350
103

nm with a more sharply defined vibronic band at 370 nm were observed which match our
observations on PCzETPMA homopolymers.
15
Similarly, excimer emission peaks around
405−420 nm were absent across the entire family of copolymers as previously shown for
PCzETPMA homopolymers which suggests a limited degree of π-stacking of the pendant groups.
15

For the unannealed low molar mass copolymers B1f −B4f (Appendix A) and to a lesser degree
also for B5f −B9f (Figure 2.2a), a broad shoulder around 400−500 nm can be seen. This feature
likely stems from optical centers that are formed in the PS-blocks upon exposure to UV light, a
phenomenon observed in a study on PS-homopolymer films that found the formation of
fluorescing diphenylpolyene centers, giving rise to fluorescence bands in the 330−520 nm
region.
35,36

After annealing, the same features in very similar relative intensities are observed with the
exception of B6f which shows an increase in intensity for the shoulder around 400−500 nm relative
to the carbazole vibronic band. PL intensities are reduced across all annealed samples implying
aggregation based PL quenching which could be indicative of a more pronounced π−π stacking
within the PCzETPMA-blocks in the annealed films.
37,38

The space charge limited current (SCLC) technique was used to measure μh for all
functionalized copolymers. Measurements for each sample were repeated three times, and the
reported data are the average over at least 20 pixels. All copolymers were spin-coated from CHCl3
and gave film thicknesses of 43−94 nm (Appendix A).
Based on previous studies on PCzETPMA homopolymers showing instances of significant
increases in μh when the polymers are annealed, SCLC was also measured after annealing at
150 °C; however, no efforts were made to optimize the annealing temperature.
104

Figure 2.2 (a) PL spectra of PS-b-PCzETPMA copolymers B5 f-B9 f for as-cast films. (b) PL
spectra of PS-b-PCzETPMA copolymers B5 f-B9 f after annealing at 150 °C for 30 min.

No significant trends were identified for samples B1f −B4f, which gave mobilities between
1.41 × 10
−7
cm
2
/V·s and 2.89 × 10
−6
cm
2
/V·s, likely owing to the low molar masses of the four
copolymers (Appendix A). Comparison with B5f −B9f supports the hypothesis that molar mass
has a significant influence on the mobilities of the copolymers since these higher molar mass
105

samples show mobilities that are up to 2 orders of magnitude higher. The hole mobilities for
unannealed and annealed copolymers B5f −B9f are depicted in Figure 2.3. For the higher molar
mass samples (Figure 2.3) certain trends are identified. First, after annealing, μh increases for all
five copolymers but has a more significant effect when PCzETPMA is the dominant block as seen
with B9f. Second, the stereoregularity of the PCzETPMA-block significantly impacts the relative
increase in mobility after annealing upon increase of the PCzETPMA-ratio in the copolymers.
Specifically, going from atactic B5f to atactic B6f the ratio of the PCzETPMA-block increases by
a factor of 1.21, and a 2.02-fold increase in mobility was measured after annealing. In comparison,
when going from isotactic B8f to isotactic B9f the PCzETPMA-block ratio increases by a factor
of 1.6, but for the mobility a much more significant 372-fold increase was measured.

Figure 2.3 Hole mobilities of copolymers B5 f-B9 f as cast and after annealing at 150 °C for 30 min.

Additionally, when looking at μh for copolymers with comparable block ratios that only differ
in the tacticity of the PCzETPMA-block, B5f versus B8f and B6f versus B9f, the isotactic
106

copolymers considerably outperform the atactic ones, a trend that is more pronounced when
PCzETPMA is the dominant block with B9f giving a μh that is higher by an order of magnitude
when compared to B6f.
Within the entire family of copolymers B9f, the only higher molar mass copolymer with a
dominant isotactic PCzETPMA-block gives the highest μh upon annealing of 2.33 × 10
−5
cm
2
/V·s,
which is consistent with our previous findings that higher levels of stereoregularity and higher
molar masses correspond to increased μh in NCPEPhomopolymers.
15,17
While the previously
reported isotactic PCzETPMA homopolymer gave a superior μh of 2.19 × 10
−4
cm
2
/V·s upon
annealing, molar mass differences between the polymers have to be considered, where Mn = 46.5
kg/mol was reported for the homopolymer and Mn = 28.2 kg/mol for the copolymer (B9f) in this
study.
15
Given the noticeable impact of molar mass on μh when going from B1f −B4f to B5f −B9f,
the even higher molar mass of the homopolymer could serve as one explanation for its superior
mobility. Additionally, the reported homopolymer has a higher triad isotacticity of 85% compared
to 80% for B9f which likely further contributes to the higher μh of the homopolymer. Interestingly,
annealing of the reported homopolymer only led to a 2.7-fold increase in μh, while in B9f a 19.7-
fold increase was measured suggesting that achieving a favorable morphology for hole transport
in the electroactive block is increasingly more dependent on thermally induced rearrangements
once a second block is introduced to the polymer structure. As an outlier, annealed B7 f with a
significantly longer PS-block than B8f gave a higher mobility, 1.27 × 10
−5
cm
2
/V·s, compared to
6.26 × 10
−6
cm
2
/V·s, indicating that PS-blocks are not just innocent bystanders but likely affect
the ordering of the copolymers, resulting in a more favorable morphology for hole transport.
Overall, the SCLC data indicate that established principles for NCPEP homopolymers hold true:
specifically, the importance of controlling stereoregularity and achieving high molar mass to
107

improve mobilities even when a second, electroinactive block is added to the structure. As such,
having a more complex block-copolymer architecture does not significantly suppress hole mobility
in cases with higher molar mass and tacticity.

2.4 Conclusion
In conclusion, we report a family of PS-b-PCzETPMA-block copolymers with varied molar
masses, tacticities, and relative block ratios as the first examples of nonconjugated block
copolymers with an electroactive block having controlled stereoregularity. Our approach allowed
us to maintain control over the stereoregularity of the NCPEP-block and synthesize well-defined
block copolymers for which the relative ratios of the two blocks were tuned. Through SCLC
measurements we were able to show that significant hole mobilities are maintained in the
copolymers compared to PCzETPMA homopolymers. Trends previously observed in the
homopolymers held true in the copolymers, most notably significant increases in hole mobility
with higher molar mass and superior mobilities for stereoregular isotactic NCPEP-blocks over
atactic ones with the highest molar mass copolymer featuring a dominant isotactic PCzETPMA-
block, B9f, giving the best mobility of 2.33 × 10
−5
cm
2
/V·s. It was also found that annealing is
significantly more critical for increasing mobility in these copolymers than in homopolymers,
suggesting that introduction of a second block into the structure strongly affects packing of the
copolymer chains. Overall, this study demonstrates that having a more complex block-copolymer
architecture does not suppress hole mobility to a significant extent. This is a promising result for
potential future application of pendant block-copolymers featuring multiple electroactive blocks
as active materials that could allow hierarchical self-organization. Future work will center around
more in-depth morphological characterization of the block copolymers.
108

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111

Chapter 3: Stereoregular Pendant Electroactive Polymers with Extended Pendants via
Post-Polymerization Copper Catalyzed Azide-Alkyne Cycloaddition

3.1 Introduction
In recent years conjugated polymers (CPs) have emerged as promising materials for
application in organic photovoltaics (OPVs),
1
organic light-emitting diodes (OLEDs),
2
and organic
field-effect transistors (OFETs).
3,4
Their unique optical, electronic and semiconducting properties
in combination with their flexibility, light weight and low cost manufacturing make CPs an
increasingly attractive platform.
5-7
Despite significant advances with CPs yielding record breaking
performances, there are certain intrinsic limitations that remain unresolved. In general CPs are
characterized by poor environmental and mechanical stability as well as significantly lower
molecular weights when compared to non-conjugated polymers.
8-10
Additionally, CPs are much
more limited in polymerization methodologies, particularly for synthesizing complex architectures
capable of generating hierarchically ordered polymer structures.
8,11

An emerging class of polymers designed to address these challenges are nonconjugated
pendant electroactive polymers (NCPEPs). These polymers are characterized by a fully non-
conjugated backbone with electroactive pendant groups attached to the side chains. This class
enables access to the extensive library of polymerization methodologies developed for non-
conjugated polymers including those that are incompatible with most CPs such as living radical or
ionic polymerizations which offer significantly enhanced control.
12,13
While CPs generally
outperform NCPEPs in terms of charge carrier mobilities by orders of magnitude, our recent
studies demonstrated that through optimization of structural variables such as backbone
112

stereoregularity and the length of the spacer connecting the pedant to the backbone, hole mobilities
can be significantly improved and even exceed poly(3-hexylthiophene) (P3HT).
14-17
One of the
most critical structural variables for improved mobility is the tacticity of the polymer backbone as
demonstrated in our studies on poly(acrylate)- and poly(methacrylate)-based NCPEPs for which
the stereoregular polymers exhibited hole mobilities that were several orders of magnitude higher
than their stereorandom analogues.
For stereorandom NCPEPs in OLED and perovskite solar cell applications the size of the
pendant group was shown to be an important variable impacting mobilities, with high mobilities
reported for more extended pendant groups.
18-21
The same trend was found by Thelakkat et al.
when systematically extending a triphenylamine pendant group resulting in an increase of hole
mobility by an order of magnitude in atactic NCPEPs.
22,23

While there are a number of studies by ourselves and others that investigated structure-property
relationships in stereoregular NCPEPs with different polymer backbones spanning
poly(styrenes),
24,25
poly(vinyls),
26-28
poly(acrylates),
14,15,29
and poly(methacrylates)
16,17
the
polymers in these studies were all functionalized with simple electroactive pendant groups, most
commonly carbazole. Reports on structure-property relationships for extended pendant groups
however are limited to stereorandom NCPEPs. Here, we report a study on the impact of pendant
group extension on both the synthesis and properties of stereoregular NCPEPs. Specifically, we
focus on extension from carbazole to 3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-carbazole.
To selectively study the effects of an extension of the pendant group deconvoluted from
superimposed effects of molecular weight and tacticity of the non-conjugated polymer backbone,
the same backbone must be functionalized with the respective pendant groups post-
polymerization. This requires a robust functionalization methodology that quantitatively
113

functionalizes stereoregular polymer with various pendant groups. In our previous studies on the
effects of stereoregularity, spacer length and backbone architecture, we were able to successfully
demonstrate >99% conversion in post-polymerization functionalizations with carbazole both via
ZnTAC24-catalyzed transesterifications of PMAs
15
and via DMPA-catalyzed photochemical
thiol-ene reactions on PAMAs.
16
However, in the present work upon extending the size of the
pendant group to 3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-carbazole both methodologies failed to
produce fully functionalized polymers even after tuning of reaction conditions in terms of the
reaction times and equivalents of pendant unit and catalyst (Supporting Information).
Alternative reported transesterification conditions using a TBD catalyst as established by
Sumerlin et al. or a titanium alkoxide (Ti(IV)(O
i
Pr)4) for which successful post polymerization
functionalization of PMA with unsubstituted carbazole was verified, were also unsuccessful.
30,31

Translating the photochemical thiol-ene condition for PAMAs to a scandium-catalyzed route that
would circumvent potential photochemical issues with the extended pendant were also
unsuccessful.
32
Detailed reaction conditions and
1
H-NMR spectra of these attempted post-
polymerization functionalizations can be found in the Supporting Information. Therefore, we
decided to explore copper-catalyzed azide-alkyne cycloaddition and we found this to be the only
method that allowed for quantitative functionalization of a stereoregular pendant polymer with
3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-carbazole as schematically shown in Figure 3.1.
114

Figure 3.1 Compatibility of post-polymerization functionalization methods with 3,6-bis(4-(2-
ethylhexyl)thiophen-2-yl)-carbazole.

3.2 Synthesis
The successful synthesis route is shown in Scheme 3.1 and was inspired by Kitayama et al.
reporting a stereoregular polymer that was fully functionalized with 9-(azidomethyl)anthracene
via copper-catalyzed click chemistry.
33
Inspired by our previously established procedures for
anionic polymerization of allyl methacrylate, parent polymer P1 was synthesized from the silyl-
protected alkyne monomer using diphenylhexyl lithium (DPHLi) initiated anionic
polymerization.
16
We found that polymerization in toluene at low temperatures gave highly
115

isotactic P1 with 83% triad isotacticity with a high molar mass of M n = 35.72 kg/mol and a
dispersity of Đ = 2.86 (Table 3.1). Tacticity was determined from
1
H-NMR spectroscopy
according to a previously published method for stereoregular poly(PgMA).
33
Stirring P1 with
excess K2CO3 at room temperature gave the fully deprotected polymer poly(propargyl
methacrylate) poly(PgMA) P2.
33
Successful deprotection of P1 is monitored by disappearance
of the trimethylsilyl-peak in the
1
H-NMR at 0.19 ppm and simultaneous appearance of the
terminal alkyne hydrogen at 2.51 ppm (Appendix B). Due to very limited solubility in 1,2,4-
trichlorobenzene even at high temperatures no GPC data could be reported for P2.
Functionalization of P2 with the conditions employed by Kitayama et al. based on CuI and
i
Pr2EtN gave a reaction mixture from which the copper species could not efficiently be removed
when applied to our pendant group, however switching to click conditions reported by Thelakkat
et al. for functionalization of stereorandom poly(perylene bisimide acrylate) pendant polymers
gave poly((carbazolyl-alkyl-triazolyl)methyl methacrylates) PCzATMMAs P3-P5 functionalized
with carbazole-based pendant groups with molar masses of Mn = 38.64 to 71.59 kg/mol (Table
3.1).
33,34
As summarized in Table 3.1 this resulted in polymers with >99% functionalization as
determined from
1
H- and
13
C-NMR spectroscopy. Functionalization of P2 is monitored via
disappearance of the distinct peaks of the two carbon atoms of the terminal alkyne groups in the
13
C-NMR spectra at 77.78 ppm and 74.47 ppm. As shown in the supporting information, no trace
of those peaks is observed in the
13
C-NMR spectra of the functionalized polymers P3-P5. P5 is
the first example of a stereoregular NCPEP featuring such an extended pendant group to the best
of our knowledge. Importantly, copper-click chemistry proved to be the only methodology
compatible with this extended pendant group.
Within the family of functionalized polymers P3-P5 two variables are selectively tuned: the
length of the spacer connecting the electroactive pendant group to the polymer backbone and the
116

pendant group itself. With P3 and P4 unsubstituted carbazole is used while the spacer length in
between the triazole-moiety and the pendant group increases from two carbons for P3 to six
carbons for P4.

Scheme 3.1 Synthesis of isotactic poly(propargyl methacrylate) poly(PgMA) P2 and its
functionalization with (substituted) azide-carbazoles to give polymers P3-P5.

Table 3.1Molecular Weights, Dispersities, Polymer Yields/Conversions and Triad Tacticities for
the Family of Polymers.
Polymer Mn [kg/mol] Đ Yield [%] Triad Tacticity [%] (mm/mr/rr)
P1 35.72 2.86 53
a
83/13/4
P2 - - 77
a
83/13/4
P3 38.64 5.46 >99
b
83/13/4
P4 71.59 3.43 >99
b
83/13/4
P5 38.84 2.08 >99
b
83/13/4
a
Isolated polymerization yields after purification.
b
Thiol–ene conversions as determined from
1
H-NMR.
117

Inspired by our previous studies on poly(N-carbazolylalkyl acrylates) (PCzXAs) where a six
carbon spacer was found to be the optimal length for achieving high hole mobilities, we chose to
synthesize one polymer which would have a similar overall distance to the backbone including the
newly formed triazole unit in P3.
15
Additionally, we synthesized a polymer that maintains the ideal
six carbon alkyl spacer starting at the triazole with P4, since this moiety could be capable of
forming a more ordered structure by π- π stacking, as observed between triazoles and aromatic
groups such as triphenylene and benzenes, such that the stacked triazoles could be considered as
part of a more extended backbone structure.
35,36
For P5 a six-atom distance to the triazole was
maintained but the pendant group itself was extended by substitution of the carbazole with
ethylhexyl-thiophene. Ethylhexyl-sidechains on the thiophene are included to prevent any
potential solubility issues.

3.3 Results and Discussion
All functionalized polymers P3-P5 were characterized via differential scanning calorimetry
(DSC). P3 showed a slight endothermic peak around 120 °C likely stemming from the glass
transition of the polymer while no significant features could be identified for polymers P4 and P5.
The absence of peaks associated with melting or crystallization for all polymers suggest a primarily
amorphous morphology.
Additionally, the functionalized polymers, both unannealed and annealed at 150 °C for 30 min,
were analyzed by thin-film UV/Vis absorption (Appendix B). P3 and P4, bearing unsubstituted
carbazole, both show characteristic n- π
*
transitions around 330 and 344 nm and π- π
*
transitions
around 295 nm, consistent with our previous studies on poly(N-carbazolylalkyl acrylates)
118

(PCzXAs) and poly((N-carbazolylethylthio)propyl methacrylates) (PCzETPMAs) bearing the
same pendant group.
15,16
For P5 the extended causes a bathochromic shift of the π- π
*
transitions giving rise to a broad
peak in the range of 270 to 370 nm with a maximum at 320 nm and a shoulder at 350 nm. These
results are consistent with the absorption behavior observed for small molecule 3,6-dithienyl-
carbazoles and their derivatives in literature.
37,38
Annealing did not lead to any changes in the
observed features for the three polymers.
Photoluminescence spectra were also measured for the unannealed (Figure 3.2a) and annealed
(Figure 3.2b) functionalized polymers. For unannealed P3 and P4 the 0-0 transition at 350 nm
and a sharply defined vibronic band at 370 nm, characteristic of carbazole, were observed while
only weak excimer emission peaks around 405-420 nm were observed. This is indicative of only
a limited degree of π-stacking of the pendant groups and is consistent with our previous findings
for PCzETPMAs bearing carbazole pendants.
16
Similar to the absorption spectra, a bathochromic
shift was observed for the emission spectra of P5 shifting the 0-0 transitions to 395 and 420 nm
with a shoulder at around 450 nm. These emission bands as well as their relative shift compared
to the less extended carbazole pendant are consistent with emission data previously reported for
small molecule 3,6-dithienyl-carbazoles.
37,39
119

Figure 3.2 (a) PL spectra of P3-P5 in as-cast films. (b) PL spectra of P3-P5 after annealing at
150 °C for 30 min.

As evident from Figure 3.2b, upon annealing, the intensity of the vibronic band at 370 nm
increased in intensity relative to the 0-0 transition at 350 nm for P3 and P4 while for P5 the band
at 420 nm increased in intensity relative to the one at 395 nm. For P3 a significant decrease in
overall PL intensity can be observed after annealing suggesting enhanced aggregation-based
quenching in the annealed film which could be the result of increased π- π stacking of the pendant
120

groups.
40,41
PL intensities for P4 and P5 on the other hand remain mostly unchanged indicative of
similar degrees of π- π stacking before and after annealing.
Hole mobilities (μh) were measured for polymers P3-P5 via the space charge limited current
(SCLC) technique by spin-coating from CHCl3. The resulting film thicknesses ranged from 63-75
nm (Appendix B). For each sample measurements were repeated three times and the reported data
was averaged over at least 20 pixels. As in our previous studies on PCzXAs and PCzETPMA
homopolymers and PS-b-PCzETPMA block-copolymers we found annealing to have a significant
effect on μh. Mobility was measured for unannealed films and after annealing at 150 °C and 210
°C as shown in Figure 3.3.
14-17
The as-cast films gave mobilities between 3.06 × 10
-7
cm
2
/V∙s and 7.15 × 10
-6
cm
2
/V∙s with
P4 giving the highest μh which was an order of magnitude higher than for P3 and P5. Upon
annealing at 150 °C, mobilities increased about an order of magnitude for all samples and gave μh
between 1.91 × 10
-6
cm
2
/V∙s and 4.79 × 10
-5
cm
2
/V∙s. P4 exhibited the highest mobilities out of
the three polymers under all tested annealing conditions and gave the highest μh overall after
annealing at 210 °C at 7.22 × 10
-5
cm
2
/V∙s, a 1.5-fold increase relative to its mobility after
annealing at 150 °C. Annealing at this higher temperature led to a 2.7-fold increase in μh for P5
and more significantly an increase by more than one order of magnitude for P3 resulting in a
mobility of 5.26 × 10
-5
cm
2
/V∙s. The observed increases in mobility upon annealing are consistent
with our previous findings for PCzXA and PCzETPMA pendant polymers.
15,16
121

Figure 3.3 Hole mobilities of polymers P3-P5 as cast and after annealing at 150 °C for 30 min and
210 °C for 30 min.

When comparing the mobilities for P3 and P4, a clear effect of the spacer length can be
observed with the six-atom spacer leading to higher μh compared to the two-atom spacer especially
after annealing at 150 °C. Upon annealing at 210 °C, a more significant increase in mobility was
observed for P3, however μh for P4 was still almost 1.5-times higher than μh for P3. This suggests
that the longer, more flexible spacer in P4 is more responsive annealing at lower temperatures than
the shorter spacer in P3. The μh for P4 annealed at 210 °C is very similar to the previously reported
μh of isotactic PCzETPMA (1.47 × 10
-4
cm
2
/V∙s) with a six carbon alkyl spacer and no triazole
moiety.
16

Similar to our previous finding for alkyl spacers in PCzXAs, these results demonstrate that the
length of the spacer significantly impacts the hole mobility of triazole-containing polymers, with
a six atom spacer separating the triazole moiety from the pendant group giving a μh that depending
122

on the exact annealing conditions is up to an order of magnitude higher than that of the two atom
spacer.
When keeping the spacer length constant at six atoms but going from the unsubstituted
carbazole as the pendant group for P4 to 3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-carbazole for P5
with an extended core and additional branched side-chains, a noticeable effect on the resulting μh
is observed. In unannealed films P4 has a higher mobility than P5 which then increases by two
orders of magnitude when the film is annealed at 210 °C while P5 only increases by one order of
magnitude. It is expected that the increased steric demand of the extended pendant group in P5,
particularly due to the branched side-chains, is likely preventing optimal stacking of the π-system
for hole transport at this particular fixed spacer length which could serve as one possible
explanation for the decrease in mobility. Such adverse π –π interactions have previously been
reported by Wang et al. for similar 3,6-disubtituted carbazoles as electroactive pendant groups in
atactic non-conjugated polymers as a result of the substituent containing sterically demanding tBu-
groups.
42
3.4 Results and Discussion
In conclusion, we report the synthesis and characterization of a family of novel PCzATMMA
polymers with varied spacer lengths and pendant groups that were extended from carbazole to 3,6-
bis(4-(2-ethylhexyl)thiophen-2-yl)-carbazole. Importantly, we report on a copper-catalyzed click
cycloaddition for post-polymerization functionalization that was demonstrated to be the only
established method compatible with this extended pendant group. This extension allowed us to
investigate for the first time the effects of the pendant group in stereoregular NCPEPs. This is also
the first study to investigate spacer length effects for stereoregular NCPEPs functionalized via
azide-alkyne click chemistry. In agreement with our previous study on PCzXAs we found the
123

spacer length of PCzATMMAs to have a significant effect on the respective hole mobilities, with
a six carbon spacer giving μh up to an order of magnitude higher than a two carbon spacer for
annealed samples. Future work will focus on further elucidating the impact of pendant group size
and solubilizing group impact on post-polymerization methodology and polymer physical and
electronic properties.

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127

Chapter 4: Impact of Pendant Substituents on Post-Polymerization Functionalization
and Electronic Properties in Stereoregular Non-Conjugated Electroactive Pendant
Polymers
4.1 Introduction
Motivated by the unique advantages associated with organic electronic devices such as organic
light emitting diodes (OLEDs)
1
, organic photovoltaics (OPVs)
2
and organic field effect transistors
(OFETs)
3
compared to their inorganic counterparts including lighter weights, lower costs,
flexibility and the prospect of convenient roll-to-roll processing, conjugated polymers (CPs)
gained considerable attention over the last decades.
4-6
However, despite impressive progress in the
field of CPs that has enabled record breaking device performances, there are still a number of
critical limitations associated with CPs. Molecular weights are significantly lower compared to
non-conjugated polymers, environmental and mechanical stability are very limited and there are
only a few polymerization methodologies available which generally do not allow for the synthesis
of advanced architectures such as block-copolymers.
4,7,8

In response to these challenges, the novel class of non-conjugated pendant electroactive
polymers (NCPEPs) is receiving increasing interest as an alternative to CPs with the potential to
overcome these limitations without compromising the advantageous properties associated with
CPs. NCPEPs are polymers based on fully non-conjugated backbones with electroactive pendant
groups attached to their side chains. While CPs generally outperform most NCPEPs reported to
date in terms of charge-carrier mobility by orders of magnitude, recent work in our group
demonstrated that through careful optimization of structural variables such as stereoregularity of
the backbone and length of the spacer between the backbone and the pendant group, hole mobilities
128

can be significantly improved and even outperform the well-known CP poly(3-hexylthiophene)
(P3HT).
9-11

To allow for improved rational design of high performance NCPEPs with enhanced charge
carrier mobilities, developing a better understanding of the fundamental structure-property
relationships for this emerging class of materials is imperative. One structural variable that has
remained largely underexplored, particularly in stereoregular NCPEPs, is the pendant group itself.
While there have been reports on the effects of changing the position of substituents on the pendant
group to afford structural isomers
12
, extending the size of the pendant moitiey
13,14
and even
introducing electron-donating and withdrawing substituents onto the pendant group
15
, all of these
studies were conducted on atactic polymers.
Given the significant increase in hole mobilities that we have demonstrated for isotactic
poly((N-carbazolylethylthio)propyl methacrylate) (PCzETPMA) compared to atactic
PCzETPMA
11
, we set out to systematically investigate substituent effects of the carbazole pendant
group for this type on a stereoregular NCPEP by synthesizing 3,6-disubstituted carbazolyl-
ethanthiols with alkly (t-butyl), aryl (phenyl), electron donating (methoxy) and electron
withdrawing (nitrile) substituents (Figure 4.1). We selected these substituent so that effects of
electron density of the pendant group, extension of this conjugated system and introduction of
sterically demanding substituents on the pendant group could systematically be studied.
129

Figure 4.1 Extending the carbazole pendant group of PCzETPMA to various 3,6-disubstituted
carbazoles.

To allow us to selectively investigate the substituent effects without additional effects of varied
molecular weights and tacticities across the family of polymers, we intended to apply our
established photochemical post-polymerization functionalization via the thiol-ene reaction to
introduce the 3,6-disubtituted carbazoles.
11
While this strategy was successful in the case of the
130

carbazole bearing the alkyl-substituent (t-butyl) and in the case of the unsubstituted carbazole as
the control system, it was found that successful post-polymerization functionalization was not
achieved with the other functionalized carbazoles. Here, the attempted functionalization with the
selected 3,6-disubstituted carbazolyl-ethanethiols are presented and the observed limitations of the
thiol-ene post-polymerization functionalization method are discussed to enable consideration of
these limitations in future applications of this methodology for the design of NCPEPs. We also
report the effects of introducing t-butyl into the carbazole pendant group of stereoregular and
stereorandom PCzETPMAs on the optoelectronic properties of the resulting polymers

4.2 Results and Discussion
As illustrated in Scheme 4.1, the PAMA parent polymers were synthesized via anionic
polymerization using DPHLi as the initiator. For the synthesis of isotactic PAMA we followed our
established procedure for anionic polymerizations in toluene at low temperatures which was
demonstrated to afford highly stereoregular PAMAs and yielded 81% triad isotactic PAMA with
a molecular weight of 49.74 kg/mol and a dispersity of 1.73.
11
For the synthesis of the atactic
parent polymer we switched to a toluene/THF cosolvent system based on a report by Brownstein
et al. showing that addition of as little as 2.5 vol.-% THF to the reaction mixture leads to
stereorandom polymers.
16
Here atactic PAMA with a molecular weight of 28.42 kg/mol and a
dispersity of 2.49 was prepared. As described in detail in Appendix C, triad tacticities were
determined from
1
H-NMR according to our previous published method for PAMAs.
11,17

For functionalization of the PAMAs using thiol-ene click chemistry, a family of four 3,6-
disubstituted carbazolyl-ethanethiols with chemically distinct substituents was synthesized in
addition to an unsubstituted carbazolyl-ethanethiol. Substituents include an alkyl, -t-Bu, an aryl,
131

-Ph, an electron donating substituent, -OMe and an electron withdrawing substituent, -CN.
Synthetic routes for all respective compounds are described in Appendix C. An accurate
investigation of substituent effects as an isolated variable requires the use of a post-polymerization
functionalization method to ensure superimposed effects of varied molecular weights and
tacticities in between the differently substituted polymers are avoided. Therefore, we decided to
employ our previously reported post-polymerization functionalization method based on
photochemical thiol-ene click chemistry which has proven effective for the quantitative
functionalization of stereorandom and stereoregular PAMAs with unsubstituted carbazolyl-
ethanethiol.
11
Using our reported thiol-ene reaction, as shown in Scheme 4.1, fully functionalized
polymers were obtained with 3,6-di(t-Bu)-carbazolyl-ethanethiol and with carbazolyl-ethanethiol,
however for the carbazolyl-ethanethiols substituted with -Ph, -OMe and -CN at best partially
functionalized polymers were obtained.
Fully functionalized polymers were obtained when the PAMAs were reacted with N-
carbazolylethanthioate and di-t-butyl-N-carbazolylethylthioate respectively under UV irradiation
(λ = 300 nm) in the presence of the photoinitiator 2,2-dimethoxy-2-phenylacetophenone (DMPA)
yielding the functionalized PCzETPMAs in ≥96% conversion. Functionalization was monitored
by
1
H-NMR spectroscopy via disappearance of the characteristic alkene peaks in PAMAs and the
simultaneous appearance of the aliphatic spacer, substituent peaks, and the aromatic carbazole
peaks. Functionalization with N-carbazolylethanthioate afforded PCzETPMAs with Mn = 20.31-
24.55 kg/mol and Đ ≤ 1.82 while functionalization with di-t-butyl-N-carbazolylethylthioate
afforded PCzETPMAs with Mn = 65.01-66.92 kg/mol and Đ ≤ 2.98 (Table 4.1).
For 3,6-di(Ph)-carbazolyl-ethanethiol the low solubility of the pendant group in common
organic solvents required significantly higher dilution of the reaction mixture for the thiol-ene
132

reaction. As determined from
1
H-NMR analysis of the filtrate after filtration of the polymer
products, this favored the photochemical dimerization of the thiols to 1,2-bis(2-(3,6-diphenyl-9H-
carbazol-9-yl)ethyl)disulfane over the thiol-ene reaction and resulted in a virtually insoluble
product.
In the case of 3,6-di(CN)-carbazolyl-ethanethiol not even a partially functionalized polymer
could be recovered suggesting that photochemical side reactions occurred instead of the intended
thiol-ene click reaction. This could be explained by the aromatic nitrile-moieties acting as
photochemically active groups themselves analogously to the established photochemical behavior
of benzonitriles which have been shown in literature to undergo photochemical [2+2]
cycloaddition in the presence of unsaturated carbohydrates under conditions very similar to those
of the thiol-ene reaction in this study.
18,19

In thiol-ene reactions with 3,6-di(OMe)-carbazolyl-ethanethiol only partially functionalized
polymers could be obtained. Due to the absence of any obvious issues related to solubility or a
photochemically active substituent, we conducted an extensive optimization study of the thiol-ene
reaction condition for this pendant group. However, tuning of the catalyst loading, the equivalents
of thiol used, the reaction time and the identity of the photoinitiator were unsuccessful in affording
a fully functionalized polymer. Additionally, an altered reaction setup in which a solution of the
polymer was slowly added over time to a mixture of the thiol and the photoinitiator stirring under
UV-light irradiation also failed. Detailed reaction conditions for all attempted thiol-ene reactions
are included in Appendix C.
133

Scheme 4.1 General synthesis of PAMA parent polymers and functionalization with (substituted)
N-carbazolylethanethioate to give poly((N-carbazolylethylthio)propyl methacrylates)
(PCzETPMAs). For R = H, tBu the initiator in the thiol-ene reaction was DMPA, the solvent was
toluene and the time was 24 hours.

Table 4.1 Molecular Weights, Dispersities, Polymer Yields/Conversions and Triad Tacticities for
the Family of Polymers.
Polymer Mn [kg/mol] Đ Yield [%] Triad Tacticity [%] (mm/mr/rr)
PAMA-ata 28.42 2.49 54
a
57/18/25
PAMA-iso 49.74 1.73 29
a
86/11/3
Cz-ata 24.55 1.78 97
b
57/18/25
Cz-iso 20.31 1.82 96
b
86/11/3
tBuCz-ata 65.01 2.17 >99
b
57/18/25
tBuCz-iso 66.92 2.98 98
b
86/11/3
a
Isolated polymerization yields after purification.
b
Thiol–ene conversions as determined from
1
H-NMR.
These results demonstrate that while photochemical thiol-ene chemistry can be a mild and
highly efficient method for post-polymerization functionalization of non-conjugated polymers,
translating to more complex pendant groups requires considerations of compatibility of these
groups with the methodology especially in terms of potential photoactive behavior of the pendant
group and sufficient solubility to minimize photochemically induced side reactions.
134

The fully functionalized polymers were characterized by several techniques. Differential
scanning calorimetry (DSC) of tBuCz-ata and tBuCz-iso showed slight endothermic peaks around
105 °C likely stemming from the glass transitions of the polymers but no features could be
observed for the polymer functionalized with unsubstituted carbazole. The absence of any peaks
that could be associated with crystallization or melting indicates amorphous morphologies across
the family of polymers.
For all polymers thin-film UV/Vis absorption was measured both for unannealed, as-cast films
and for films after annealing at 150 °C for 30 min (Appendix C). Consistent with our previous
studies on PCzETPMAs and PCzXAs, all samples displayed the absorption behaviour
characteristic for pendant carbazole groups with a peak at 295 nm corresponding to π–π*
transitions and peaks around 330 and 344 nm corresponding to n–π* transitions.
10.11
While the
absorption features for tBuCz- and Cz-substituted polymers were virtually identical, tBuCz-ata
and tBuCz-iso had lower absorption coefficients than their unsubstituted analogues. Upon
annealing no significant changes in the absorption spectra could be observed.
135

Figure 4.2 a) PL spectra of PCzETPMAs for as-cast films. (b) PL spectra for PCzETPMAs after
annealing at 150 °C for 30 min.

Additionally, photoluminescence (PL) spectra were measured for both the unannealed (Figure
4.2a) and the annealed (Figure 4.2b) functionalized polymers. Cz-iso and Cz-ata exhibited the
emission features typical for 0-0 transitions in pendant carbazoles with a peak at 350 nm and a
vibronic band at 370 nm. Consistent with our previous reports on poly(methacrylates)
functionalized with carbazole pendant groups, peaks around 405-420 nm corresponding to excimer
136

emission from fully overlapping carbazoles were absent, however a shoulder around 440 nm likely
stemming from lower energy excimer emission as reported for adjacent carbazoles in 2,4-di-N-
carbazolylpentane and norbornene-derived non-conjugated polymers with pendant carbazoles
could be observed.
10,11,20.21
This suggests a limited degree of π-stacking for the unannealed
samples. tBuCz-iso and tBuCz-ata displayed characteristic 0-0 transitions as well however a slight
bathochromic shift of ~10 nm of the peaks was observed. The intensity of the shoulder at 440 nm
relative to the intensity of the peaks corresponding to the 0-0 transition was decreased compared
to the Cz-polymers which is indicative for a more limited degree of excimer formation in these di-
substituted polymers relative to their unsubstituted analogues.
In the PL spectra after annealing shown in Figure 4.2b the same features but at different
relative intensity were observed. The intensity of the shoulder at 440 nm was decreased relative to
the intensity of 0-0 transition and the vibronic band at 370 nm especially for Cz-iso and Cz-ata
indicating a relative decrease of the contribution of emission stemming from excimers. While the
overall PL intensity of Cz-ata is slightly increased upon annealing, the intensities for all other
samples decrease.
Decreased intensities suggest increased aggregation-based PL quenching indicative of more
pronounced π–π stacking of the stacking of the carbazole groups in the annealed polymers. This is
consistent with both our previous observations for annealed PCzETPMAs and the established
phenomenon of “aggregation-causes quenching” (ACQ) for luminophores and fluorophores which
has been observed in carbazole containing small molecules amongst numerous other comounds.
22-
26
For Cz-ata however the increased PL intensity would suggest a decrease in the degree of π–π
stacking despite an increase in hole mobility after annealing as discussed below. Overall, for
137

PCzETPMAs with a six atom spacer, annealing appears to induce higher levels of aggregation of
the tBuCz pendant group than for the Cz group.

Figure 4.3 Hole mobilities of PCzETPMA polymer with Cz and tBuCz pendant groups as cast
and after annealing at 150 °C for 30 min.

To further elucidate the impact of structure and annealing on electronic properties, hole
mobilities (μh) were measured for the functionalized polymers via the space charge limited current
(SCLC) technique. Based on previous findings for PCzETPMA homopolymers that showed
significantly improved mobilities after thermal annealing, we measured all samples as-cast and
after annealing at 150 °C, however no attempts were made to optimize the annealing conditions.
For each sample measurements were repeated three times and the reported data shown in
Figure 4.3 are the average over at least 20 pixels. The polymers were spin-coated from chloroform
and gave film thicknesses of 56-70 nm (Appendix C). Hole mobilities were found to follow three
major trends: μh was higher for the stereoregular polymers compared to their stereorandom
analogues, for any given polymer backbone μh was higher when the attached pendant group was
138

Cz rather than tBuCz, and μh increased for all samples after annealing. Prior to annealing, Cz-iso
exhibited the highest hole mobility of 5.04 × 10
-5
cm
2
/V∙s, which was about five times higher than
measured for for tBuCz-iso. The mobility of Cz-ata, 3.94 × 10
-5
cm
2
/V∙s, was lower than for its
stereoregular analogue however the decrease was less significant than for tBuCz-ata which gave a
μh that was an order of magnitude lower than all other samples. The superior mobility for the
isotactic samples is consistent with our previous findings comparing stereoregular and
stereorandom PCzETPMAs and can be attributed to a more favourable positioning of the pendant
groups for intramolecular charge carrier transport.
10,11
The lower hole mobilities for the tBuCz-
polymers compared to the Cz-polymers is likely the result of the additional steric bulk of the tert-
butyl substituents that hinder more optimal overlap of the π-conjugated systems of the carbazole
moieties needed for efficient hole transport. Such adverse π–π interactions as the result of terminal,
bulky t-butyl groups have previously been described by Wang et al. for more extended 3,6-
disubstituted-carbazole based pendant groups in atactic polymers which resulted in decreased
performances for perovskite solar cell devices.
27

Consistent with our studies on PCzETPMAs and PCzXAs, μh improved across all samples after
annealing.
10,11
The trends observed for the annealed samples were the same as described for the
as-cast samples with annealed Cz-iso giving the highest hole mobility of 1.09 × 10
-4
cm
2
/V∙s, an
increase by about a factor of two. This is in good agreement with our previous report on isotactic
PCzETPMA functionalized with a carbazole pendant group which gave a μh of 2.19 × 10
-4
cm
2
/V∙s
under the same annealing conditions. Annealing was found to have the most significant effect on
tBuCz-ata for which μh increased by an order of magnitude resulting in a hole mobility of 2.96 ×
10
-5
cm
2
/V∙s.

139

Figure 4.4 a) DFT-optimized structures of Cz polymers with 40 repeating units and highlighted
polymer backbone. Reprinted with permission from Samal et al.
11
Copyright 2021 American
Chemical Society. b) DFT-optimized structures of tBuCz polymers with 40 repeating units and
highlighted polymer backbone.

μh of tBuCz-iso was only marginally higher suggesting that for a fixed spacer length of six
atoms in PCzETPMAs with such bulky substituents the polymer conformations assumed after
thermally induced rearrangement are more heavily influenced by the steric demand of the
substituent than by the tacticity of the backbone which results in similar positioning of the pendant
groups and thus similar charge transport properties in polymers of both tacticities. However,
whether this effect upon introduction of bulky substituents can be more universally observed for
PCzETPMAs with varied spacer lengths was not investigated in this study.
Considering the amorphous nature of the polymers as determined from DSC, we decided to
turn to simulations of the polymer chains by DFT to gain further insight into their packing behavior
(Figure 4.4). We followed our approach from previous studies and optimized atactic and fully
isotactic PCzETPMA chains with tBuCz pendant groups with 40 monomers by B3LYP/6-31+G
in Q-Chem 5.2.
10,11,29
The obtained structures were compared to the optimized geometries for
atactic and isotactic PCzETPMAs with Cz pendant groups from a previous report. Cz-ata showed
a distinctly more clumped and randomized structure with very limited π–π stacking between the
pendant groups compared to Cz-iso which had a significantly more ordered, elongated, helical
140

backbone with only slight distortion and displayed π–π stacked dimers and trimers. Upon
introduction of the t-butyl substituents, the atactic polymer tBuCz-ata displayed less clumped,
more linearly stretched structure with only very limited π–π stacking between the pendant groups.
The backbone of tBuCz-iso displayed a helix like structure however as a result of the increased
steric demand of the substituted pendant groups with significantly more distortion and less
elongated compared to the backbone of Cz-iso. Due to this pronounced distortion, π–π stacking
between pendant groups was distinctly reduced relative to Cz-iso with no trimers and only very
limited amounts of stacked dimers. Overall, the optimized structures for both tBuCz polymers
indicate significantly reduced π–π stacking relative to their Cz analogues which is in good
agreement with the reported hole mobility data and support the hypothesis of significantly reduced
ordering of the pendant groups in the tBuCz-polymers regardless of the tacticity of the backbone
due to the introduction of such a bulky substituent which then leads to lower hole mobilities than
in the Cz-polymers.

4.3 Conclusion
In summary, this work is the first study on the impact of pendant functionalization on post-
polymerization chemistry and properties in stereoregular NCPEPs. A family of five carbazolyl-
ethanethiols was synthesized and tested in photochemical thiol-ene post-polymerization reactions.
The limitations of this functionalization method were observed for three of these thiols, namely
limited solubility in the case of 3,6-di(phenyl)-carbazolyl-ethanethiol and photochemical side
reactions preventing complete functionalization of the PAMA parent polymer. For the successfully
functionalized PCzETPMAs with unsubstituted carbazolyl-ethanethiol and 3,6-di-t-butyl-N-
carbazolylethylthioate a distinct effect of substitution on the hole mobilities μh of the resulting
141

polymers could be observed. Similar to our previous findings for PCzETPMAs, annealing lead to
significantly increased μh regardless of the nature of the pendant group or the tacticity of the
polymer backbone. Both isotactic and atactic tBuCz polymers exhibited lower mobilities than their
analogues bearing unsubstituted carbazole pendants. The effect of stereoregularity on μh decreased
with the introduction of the t-butyl substituents resulting in similar mobilities for iso-tBuCz and
ata-tBuCz while iso-Cz exhibited significantly higher μh compared to ata-Cz. These results
demonstrate that at a fixed spacer length of six atoms introducing bulky substituents minimizes
the impact of backbone tacticity and leads to lower mobilities. The experimental findings were
supported by structural modelling of polymer chains using DFT which found significantly reduced
ordering of the polymer backbone and less overall of the pendant groups specifically in the
isotactic polymer for the spacer length discussed here after introduction of the tBuCz-substituents.
This work can serve as a guideline for the rational design of future, more extended and substituted
NCPEPs and aid in determining the compatibility of certain pendant groups for post-
polymerization functionalization via the photochemical thiol-ene click chemistry.

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145

Biographical Sketch

Alexander Schmitt was born in Mannheim, Germany. He received his Bachelor of Chemistry
degree in 2018 from the Technical University of Munich (TUM) where he was advancing research
on oxide-supported Iridium catalysts for application in electrolysis in the researching group of Prof.
Hubert A. Gasteiger. Under the mentorship of Prof. Thorsten Bach, Technical University of
Munich, and Prof. Barry C. Thompson, University of Southern California, he received his Master
in Chemistry from the Technical University of Munich (TUM) in 2019 for his work on the
synthesis of conjugated polymers via copper-catalyzed direct arylation and of non-fullerene
acceptors for applications in organic solar cells. In 2018 he began his Ph.D. studies at the
University of Southern California (USC) where he joined the research group of Prof. Barry C.
Thompson in 2019. His research is focused on the synthesis of electroactive polymers for organic
photovoltaics with a focus on non-conjugated electroactive pendant polymers.

146

Appendices
Appendix A: Synthesis of Block Copolymers Containing Stereoregular Pendant
Electroactive Blocks

A.1 Materials and Methods
All reactions were performed under dry N2 in oven dried glassware, unless otherwise noted.
Unless noted otherwise, all reagents were purchased and used as received from commercial
sources though VWR. Solvents were purchased from VWR and used without purification, unless
otherwise noted. Toluene was dried over CaH2 before being distilled and stored over 3Å sieves.
THF was dried over sodium before distilled and stored over 3Å sieves.
All
1
H-NMR were recorded at 25 °C using CDCl3 on either a Varian Mercury 400 MHz, Varian
VNMRS-500 MHz, or a Varian VNMR-600 MHz. All spectra were referenced to CHCl3
(7.26 ppm), unless noted otherwise. Number average molecular weights (Mn) and dispersity (Ð)
were determined by size exclusion chromatography (SEC) on four 300 x 7.5 mm PL1110 Mixed
high grade organic columns (Agilent) at 140 °C using an Agilent PL-GPC separation module and
an Agilent 1260 Infinity II RI detector. All samples were dissolved in HPLC grade
trichlorobenzene at a concentration of 1.0 mg/mL, briefly heated and then allowed to cool to room
temperature prior to filtering through a 0.2 µm PTFE filter. The instrument was calibrated vs.
polystyrene standards (1050−3,800,000 g/mol), and data were analyzed using Agilent GPC/SEC
software.
For polymer thin-film measurements, solutions were spin-coated onto pre-cleaned glass slides
from chloroform (CHCl3) solutions at 7 mg/mL. UV-Vis absorption spectra were obtained on a
147

PerkinElmer Lamda 950 spectrophotmeter. Photoluminescence (PL) measurements were
performed on a Photon Technology International QuantaMaster C-60 Spectrometer using the
Qm/Ex300 Em400 light source with an excitation wavelength of λ = 310 nm, a 5 mm slit-width, a
step-size of 2 nm and an integration of 0.5 seconds and analyzed using the Felix GX software.
The thicknesses of the thin films were obtained using a Film-Sense FS-1 Ellipsometer and the
Film-Sense FS-1 analysis software version 1.59 in Single Measurement mode using the Cauchy
on Si with k3 model as the average of five measurements across the slide.
Differential scanning calorimetry (DSC) profiles were recorded on a Perkin-Elmer DSC 8000
with a scan rate of 10 °C/min. The sample size was ~ 5 mg; polymers were used as obtained after
purification. The first cycle for each sample is depicted in Figures A.45-A.62 below because no
features were visible in the second cycles. The heating/cooling protocol used is:
1. Hold for 2.0 min at 20.0 °C
2. Heat from 20.0 °C to 300.0 °C at 10.0 °C/min
3. Cool from 300.0 °C to 20.0 °C at 10.0 °C/min
4. Heat from 20.0 °C to 300.0 °C at 10.0 °C/min
5. Cool from 300.0 °C to 20.0 °C at 10.0 °C/min
All DSC traces in Figures A.45-A.62 show the same sharp feature at ~ 50 °C which is an
artifact stemming from the instrument and the samples themselves.
Mobility was measured using a hole-only device configuration of
ITO/PEDOT:PSS/Polymer/Al in the space charge limited current regime (SCLC). All steps of the
device fabrication and testing were performed in air. ITO-coated glass substrates (10 Ω/square,
Thin Film Devices Inc.) were subsequently cleaned by sonication in detergent, de-ionised water,
tetrachloroethylene, acetone and isopropyl alcohol and dried in a N2 stream. A thin layer of
PEDOT:PSS (Clevios PH500, filtered with a 0.45 μm PVDF syringe filter – Pall Life Science)
148

was first spin-coated on the pre-cleaned ITO-coated glass substrate and annealed at 130 °C for 60
minutes under vacuum. Polymer solutions were prepared in chloroform and stirred for 24 hours at
40 °C. The polymer active layer was spin-coated (with a 0.45 μm PTFE syringe filter – Whatman)
on top of the PEDOT:PSS layer. Films were placed in a nitrogen cabinet for 20 minutes before
being transferred to a vacuum chamber. The substrates were pumped down to a high vacuum and
aluminium (100 nm) was thermally evaporated at 3-4 Å/s using an Angstrom 01353 Coating
System onto the active layer through shadow masks to define the active area of the devices. The
dark current was measured under ambient conditions. At sufficient potential the mobilities of
charges in the device can be determined by fitting the dark current to the model of SCL current
and is described by the following equation where JSCLC is the current density, ε0 is the permittivity
of space, εR is the dielectric constant of the polymer (assumed to be 3), μ is the zero-field mobility
of the majority charge carriers, V is the effective voltage across the device (V = Vapplied – Vbi – Vr),
and L is the polymer layer thickness:
𝐽 𝑆 𝐶𝐿𝐶 =
9
8
∙ 𝜀 𝑅 ∙ 𝜀 0
∙ 𝜇 ∙
𝑉 2
𝐿 3

The series and contact resistance of the hole-only device was measured using a blank
(ITO/PEDOT/Al) configuration and the voltage drop due to this resistance (Vr) was subtracted
from the applied voltage. The built-in voltage (Vbi), which is based on the relative work function
difference of the two electrodes, was also subtracted from the applied voltage. The built-in voltage
can be determined from the transition between the ohmic region and the SCL region and is found
to be about 1 V. Polymer film thicknesses were measured using a Film-Sense FS-1 Ellipsometer
and the Film-Sense FS-1 analysis software version 1.59 in Single Measurement mode using the
Cauchy on Si with k3 model as the average of five measurements across the slides.
149

A.2 Synthetic Procedures
Synthetic procedures for the synthesis of 2-(9H-carbazol-9-yl)ethanethiol was used without
modifications as reported in literature.
1
Styrene, allyl methacrylate and 1,1-diphenylethylene were
freshly distilled from CaH2 and were stored over 3Å sieves.
General polymerization procedure:

An oven dried Schlenck-flask was flame dried three times and subsequently charger with
50 mL of solvent. The solvent was degassed by three freeze pump thaw cycles. 0.1 mL styrene
and the n-BuLi initiator were added in and stirred at room temperature for 90 minutes. Then the
remaining styrene was added in dropwise, the Schlenck-flask was sealed off under nitrogen inert
gas and stirred at room temperature overnight. After cooling the mixture to the desired temperature
the allyl methacrylate was added in dropwise and the flask was then again sealed off under nitrogen
inert gas. The resulting mixture was then stirred at the desired temperatures overnight. The reaction
was quenched by the addition of 1 mL MeOH and the solvents were removed in vacuo. The
resulting crude product was redissolved in chloroform, precipitated into 250 mL MeOH, filtered
and dried under high vacuum yielding the desired products as white solids.
The exact reaction conditions for block-copolymers B1u-B9u are listed in Table A1 and their
characterization data is summarized in Table A2.
150

Table A.1 Polymerization conditions and yields for block-copolymers B1 u-B9 u.
Copolymer
n (styrene)
[mmol]
n (AMA)
[mmol]
n (n-BuLi)
[mmol]
Solvent
Temperature
[°C]
Yield
[%]
B1 u 3.06 2.84 0.019
Toluene/THF =
14.3/1.43 mL
-78 for 5h then
RT
70%
B2 u 3.06 5.67 0.019
Toluene/THF =
14.3/1.43 mL
40 68%
B3 u 3.06 5.67 0.019 15 mL Toluene 40 57%
B4 u 3.06 5.67 0.019 15 mL Toluene
-78 for 6h then
RT
71%
B5 u 12.22 18.33 0.153
Toluene/THF =
42/8 mL
-78 for 90min
then RT
74%
B6 u 12.22 24.44 0.153
Toluene/THF =
81/9 mL
-78 for 30min
then RT
32%
B7 u 12.22 27.49 0.038 30 mL Toluene
-78 for 6h then
RT
41%
B8 u 12.22 24.44 0.153 50 mL Toluene
-94 for 5h, 45
for 4h then RT
59%
B9 u 10.27 20.54 0.031 80 mL Toluene
-78 for 6h, then
RT
22%

Table A.2 Characterization data for block copolymers B1 u-B9 u.
Copolymer
Mn PS
[kg/mol]
Đ (PS)
Mn block
[kg/mol]
Đ (block)
Yield
[%]
Tacticity PS:PAMA
B1 u 3.20 1.16 3.08 1.18 70% 52% syn 1.75 : 1
B2 u 2.60 1.51 2.36 2.60 68% 36% syn 1 : 1.26
B3 u 3.31 1.20 4.48 3.313 57% 85% iso 1.96 : 1
B4 u 6.05 1.13 7.82 1.27 71% 84% iso 1 : 1.27
B5 u 14.99 1.17 15.61 1.14 74% 57% syn 1.53 : 1
B6 u 15.27 1.31 15.98 1.19 32% 57% syn 1.11 : 1
B7 u 35.61 1.25 41.82 1.14 41% 79% iso 3.58 : 1
B8 u 23.12 1.24 25.93 1.24 59% 80% iso 1.88 : 1
B9 u 19.24 1.20 27.55 1.21 22% 78% iso 1:1.22

151

Tacticities were determined using the three distinct
1
H-NMR peaks for the methyl-group a in
the backbone of the PAMA-block for the three triad tacticities mm, mr/rm and rr with mm being
the peak corresponding to an isotactic environment for the methyl groups as establish in a previous
study.
1

The relative ratio of the PS-block and the PAMA-block to one another were determined
through integration of the corresponding peaks in the
1
H-NMR with the broad aromatic multiplet
from 6.3-7.2 ppm corresponding to the 5 aromatic hydrogens on the pendant benzene of the PS-
block and the multiplet at 5.9 ppm corresponding to the single hydrogen Hb on the terminal alkene
in the PAMA-block.
152

Precipitation in Acetone of block-copolymer versus physical mixture of the two
homopolymers:

To confirm the formation of true block-copolymers over mixtures of two homopolymers we
synthesized the respective PS and PAMA homopolymers which are characterized in Table A3 to
compare how a physical mixture of the two polymers would compare to our block-copolymers
upon precipitation in hot Acetone and subsequent filtration. This control study is based on the
solubility of especially lower molecular weight, atactic PS in Acetone as established in literature
while PAMA is expected to be insoluble in Acetone.
2-4
Table A.3 Molecular weights, dispersities and tacticities for the PS and the PAMA homopolymer.
Homopolymer Mn [kg/mol] Đ Tacticity
Polystyrene 21.50 1.46 atactic
Poly(allyl methacrylate) 24.24 2.45 81% iso
153

Initially both the unfunctionalized block-copolymer B9u and the physical mixture of the PS
and PAMA homopolymer were dissolved in chloroform, precipitated into cold MeOH and filtered.
The respective NMR spectra for the physical mixture as well as the spectra and characterization
data for the two homopolymers are shown below:

Figure A.1:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the polystyrene homopolymer
listed in table A3.
154

Figure A.2:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the poly(allyl methacrylate)
homopolymer listed in table A3.

Figure A.3:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the physical mixture of the
polystyrene and poly(allyl methacrylate) homopolymers listed in table A3.
155

Then both the block-copolymer B9u and the physical mixture of the homopolymers were stirred
in boiling Acetone, filtered and both the filtrate and the filtered off solids were analyzed by
1
H-
NMR and GPC. Upon concentration in vacuo there was no polymer detected in the filtrate in the
case of the block-copolymer. However, in the case of the physical mixture the PS and minimal
amounts of the PAMA were dissolved in the hot Acetone and were recovered from the filtrate
while the filtered off solids were exclusively undissolved PAMA.

Figure A.4:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the filtrate of the homopolymers
listed in table A3 after stirring in hot Acetone.
156

Figure A.5:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the filtered off solids from the
physical mixture of the homopolymers listed in table A3 after stirring in hot Acetone.

Figure A.6:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of block-copolymer B9u after
stirring in hot Acetone.
157

Figure A.7: GPC traces of the PS homopolymer listed in table A3 (top left), the PAMA
homopolymer listed in table A3 (top right) and the physical mixture of the two after
precipitation in cold MeOH (bottom).

158

Figure A.8: GPC traces of the filtrate (left) and filtered off solids (right) after stirring the
physical mixture of the PS and PAMA homopolymers listed in table A3 in hot Acetone
and filtering them.

Figure A.9: GPC traces of the filtered off block-copolymer B9u after stirring it in cold
MeOH (left) and in hot Acetone (right).

159

General Thiol-ene click procedure:

Two oven-dried Schlenck-flasks were flame dried three times. One was charged with 50 mg
(1 eq. with respect to the allyl methacrylate block) of the respective block-copolymer and vacuum
backfilled once. The other one was charged with the respective solvent which was degassed via
three freeze pump thaw cycles. 4 mL of the degassed solvent were added to the polymer and the
resulting mixture was heated (90 °C for toluene and 110 °C for 1,2-dichlorobenzene) until all the
polymer was dissolved. After cooling to room temperature 3 eq. of 2-(9H-carbazol-9-yl)ethane-1-
thiol and 0.5 eq. of 2,2-Dimethoxy-2-phenylacetophenone followed by 1 mL of the degassed
solvent were added in. The resulting mixture was irradiated by a 300 nm UV LED light irradiation
while covered at room temperature overnight. After precipitation in 100 mL MeOH the solids were
collected by vacuum filtration and dried under high vacuum to afford the desired products.
The exact conditions for the thiol-ene reaction for each block-copolymer as well as the
characterization data for the obtained functionalized block-copolymers B1f-B9f are listed in Table
A4.

160

Table A.4 Reaction conditions for the thiol-ene photoreactions yielding the functionalized block-
copolymers B1 f-B9 f and their characterization data.
Copolymer
n (allyl methacrylate units) in
50 mg copolymer
Solvent Mn [kg/mol] Đ
B1 f 0.162 mmol 1,2-dichlorobenzene 3.31 1.12
B2 f 0.239 mmol Toluene 3.43 1.58
B3 f 0.199 mmol 1,2-dichlorobenzene 4.56 1.18
B4 f 0.238 mmol 1,2-dichlorobenzene 10.13 1.30
B5 f 0.175 mmol Toluene 16.62 1.10
B6 f 0.207 mmol Toluene 19.38 1.31
B7 f 0.100 mmol Toluene 37.27 1.27
B8 f 0.155 mmol Toluene 19.96 1.25
B9 f 0.193 mmol 1,2-dichlorobenzene 28.17 1.22

A.3
1
H-NMR spectra of the Polymers

Figure A.10:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B1f.

161

Figure A.11:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B1u.

Figure A.12:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B2f.

162

Figure A.13:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B2u.

Figure A.14:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B3f.

163

Figure A.15:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B3u.
9
Figure A.16:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B4f.

164

Figure A.17:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B4u.

Figure A.18:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B5f.

165

Figure A.19:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B5u.

Figure A.20:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B6f.

166

Figure A.21:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B6u.

Figure A.22:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B7f.

167

Figure A.23:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B7u.

Figure A.24:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B8f.

168

Figure A.25:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B8u.

Figure A.26:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B9f.

169

Figure A.27:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of B9u.

170

A.4 GPC Traces

Figure A.28: GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer
(top right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B1.

Figure A.29: GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer
(top right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B2.
171

Figure A.30: GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer
(top right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B3.

Figure A.31: GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer
(top right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B4.
172

Figure A.32: GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer
(top right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B5.

Figure A.33: GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer
(top right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B6.
173

Figure A.34: GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer
(top right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B7.

Figure A.35: GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer
(top right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B8.
174

Figure A.36: GPC traces of the PS-aliquot (top left), the PS-b-PAMA block-copolymer
(top right) and the functionalized PS-b-PCzETPMA block-copolymer (bottom) for B9.

175

A.5 UV-Vis Absorption Data

Figure A.37: UV-Vis absorption spectra of as cast low molecular weight copolymers B1f-
B4f.

Figure A.38: UV-Vis absorption spectra of low molecular weight copolymers B1f-B4f
after annealing at 150 °C for 30 min.
176

Figure A.39: UV-Vis absorption spectra of as cast high molecular weight copolymers B5f-
B9f.

Figure A.40: UV-Vis absorption spectra of high molecular weight copolymers B5f-B9f
after annealing at 150 °C for 30 min.
177

A.6 Photoluminescence Data

Figure A.41: PL emission spectra of as cast low molecular weight copolymers B1f-B4f.

Figure A.42: PL emission spectra of low molecular weight copolymers B1f-B4f after
annealing at 150 °C for 30 min.
178

Figure A.43: PL emission spectra of as cast high molecular weight copolymers B5f-B9f.

Figure A.44: PL emission spectra of high molecular weight copolymers B5f-B9f after
annealing at 150 °C for 30 min.
179

A.7 DSC Data

Figure A.45: DSC scan of polymer B1u.

Figure A.46: DSC scan of polymer B2u.
180

Figure A.47: DSC scan of polymer B3u.

Figure A.48: DSC scan of polymer B4u.
181

Figure A.49: DSC scan of polymer B5u.

Figure A.50: DSC scan of polymer B6u.
182

Figure A.51: DSC scan of polymer B7u.

Figure A.52: DSC scan of polymer B8u.
183

Figure A.53: DSC scan of polymer B9u.

Figure A.54: DSC scan of polymer B1f.
184

Figure A.55: DSC scan of polymer B2f.

Figure A.56: DSC scan of polymer B3f.
185

Figure A.57: DSC scan of polymer B4f.

Figure A.58: DSC scan of polymer B5f.
186

Figure A.59: DSC scan of polymer B6f.

Figure A.60: DSC scan of polymer B7f.
187

Figure A.61: DSC scan of polymer B8f.

Figure A.62: DSC scan of polymer B9f.
188

A.8 Mobility Data
Table A.5 Hole mobilities μ h both unannealed and annealed at 150 °C for 30 min in air and film
thicknesses for all copolymers.
Polymer μh, unannealed [cm
2
V
-1
s
-1
] μh, annealed [cm
2
V
-1
s
-1
] Thickness [nm]
B1 f (1.93 ± 0.53) ∙ 10
-6
(2.89 ± 0.53) ∙ 10
-6
60.3
B2 f (5.26 ± 0.53) ∙ 10
-7
(1.41 ± 0.53) ∙ 10
-7
63.4
B3 f (1.88 ± 0.53) ∙ 10
-6
(7.49 ± 0.53) ∙ 10
-7
62.4
B4 f (1.73 ± 0.53) ∙ 10
-6
(1.35 ± 0.53) ∙ 10
-6
62.1
B5 f (2.50 ± 0.53) ∙ 10
-6
(3.16 ± 0.53) ∙ 10
-6
52.7
B6 f (3.88 ± 0.53) ∙ 10
-6
(6.37 ± 0.53) ∙ 10
-6
94.1
B7 f (5.08 ± 0.53) ∙ 10
-6
(1.27 ± 0.53) ∙ 10
-5
42.6
B8 f (5.82 ± 0.53) ∙ 10
-6
(6.26 ± 0.53) ∙ 10
-6
42.6
B9 f (1.18 ± 0.53) ∙ 10
-6
(2.33 ± 0.53) ∙ 10
-5
65.3

A.9 References
(1) Samal, S.; Schmitt, A.; Thompson, B. C. Contrasting the Charge Carrier Mobility of
Isotactic, Syndiotactic and Atactic Poly((N-carbazolylethylthio)propyl methacrylate). ACS Macro
Lett. 2021, 10 (12), 1493-1500.
(2) Suh, K. W.; Clarke, D. H. Cohesive Energy Densities of Polymers from Turbidimetric
Titrations. J. Polym. Sci. – Part A: Polym. Chem. 1967, 5, 1671-1681.
(3) Son, K.-S.; Jöge, F.; Waymouth, R. M. Copolymerization of Styrene and Ethylene at
High Temperature with Titanocenes Containing a Pendant Amine Donor. Macromolecules 2008,
41 (24), 9663-9338.
(4) Noh, S. K.; Lee, M.; Kum, D. H.; Kim, K.; Lyoo, W. S.; Lee, D.-H. Studies of
ethylene-styrene copolymerization with dinuclear contrained geometry complexes with methyl
substitution at the five-membered ring in idenyl of [Ti(η
5
:η
1
-C9H5SiMe2NCMe3)]2[CH2]n. J.
Polym. Sci. – Part A: Polym. Chem. 2004, 42 (7), 1712-1723.

189

Appendix B: Stereoregular Pendant Electroactive Polymers with Extended Pendants via
Post-Polymerization Copper Catalyzed Azide-Alkyne Cycloaddition

B.1 Materials and Methods
All reactions were performed under dry N2 in oven dried glassware, unless otherwise noted.
Unless noted otherwise, all reagents were purchased and used as received from commercial
sources though VWR. Solvents were purchased from VWR and used without purification, unless
otherwise noted. Toluene was dried over CaH2 before being distilled and stored over 3Å sieves.
THF was dried over sodium before distilled and stored over 3Å sieves.
All
1
H-NMR were recorded at 25 °C using CDCl3 on either a Varian Mercury 400 MHz, Varian
VNMRS-500 MHz, or a Varian VNMR-600 MHz. All spectra were referenced to CHCl3
(7.26 ppm), unless noted otherwise. Number average molecular weights (Mn) and dispersity (Ð)
were determined by size exclusion chromatography (SEC) on four 300 x 7.5 mm PL1110 Mixed
high grade organic columns (Agilent) at 140 °C using an Agilent PL-GPC separation module and
an Agilent 1260 Infinity II RI detector. All samples were dissolved in HPLC grade
trichlorobenzene at a concentration of 1.0 mg/mL, briefly heated and then allowed to cool to room
temperature prior to filtering through a 0.2 µm PTFE filter. The instrument was calibrated vs.
polystyrene standards (1050−3,800,000 g/mol), and data were analysed using Agilent GPC/SEC
software.
For polymer thin-film measurements, solutions were spin-coated onto pre-cleaned glass slides
from chloroform (CHCl3) solutions at 7 mg/mL. UV-Vis absorption spectra were obtained on a
PerkinElmer Lamda 950 spectrophotmeter. Photoluminescence (PL) measurements were
190

performed on a Photon Technology International QuantaMaster C-60 Spectrometer using the
Qm/Ex300 Em400 light source with an excitation wavelength of λ = 310 nm, a 5 mm slit-width, a
step-size of 2 nm and an integration of 0.5 seconds and analyzed using the Felix GX software.
The thicknesses of the thin films were obtained using a Film-Sense FS-1 Ellipsometer and the
Film-Sense FS-1 analysis software version 1.59 in Single Measurement mode using the Cauchy
on Si with k3 model as the average of five measurements across the slides.
Differential scanning calorimetry (DSC) profiles were recorded on a Perkin-Elmer DSC 8000
with a scan rate of 10 °C/min. The sample size was ~ 5 mg; polymers were used as obtained after
purification. The second cycle for each sample is depicted in Figures S28-S30 below because no
features were visible in the second cycles. The heating/cooling protocol used is:
1. Hold for 2.0 min at 20.0 °C
2. Heat from 20.0 °C to 300.0 °C at 10.0 °C/min
3. Cool from 300.0 °C to 20.0 °C at 10.0 °C/min
4. Heat from 20.0 °C to 300.0 °C at 10.0 °C/min
5. Cool from 300.0 °C to 20.0 °C at 10.0 °C/min
All DSC traces show the same sharp feature at ~ 50 °C which is an artifact stemming from the
instrument and not the samples themselves.
Mobility was measured using a hole-only device configuration of
ITO/PEDOT:PSS/Polymer/Al in the space charge limited current regime (SCLC). All steps of the
device fabrication and testing were performed in air. ITO-coated glass substrates (10 Ω/square,
Thin Film Devices Inc.) were subsequently cleaned by sonication in detergent, de-ionised water,
tetrachloroethylene, acetone and isopropyl alcohol and dried in a N2 stream. A thin layer of
PEDOT:PSS (Clevios PH500, filtered with a 0.45 μm PVDF syringe filter – Pall Life Science)
was first spin-coated on the pre-cleaned ITO-coated glass substrate and annealed at 150 °C for 30
191

minutes under nitrogen inert gas. Polymer solutions were prepared in chloroform and stirred for
24 hours at 40 °C. The polymer active layer was spin-coated (with a 0.45 μm PTFE syringe filter
– Whatman) on top of the PEDOT:PSS layer. Films were placed in a nitrogen cabinet for 20
minutes before being transferred to a vacuum chamber. The substrates were pumped down to a
high vacuum and aluminium (100 nm) was thermally evaporated at 3-4 Å/s using an Angstrom
01353 Coating System onto the active layer through shadow masks to define the active area of the
devices. The dark current was measured under ambient conditions. At sufficient potential the
mobilities of charges in the device can be determined by fitting the dark current to the model of
SCL current and is described by the following equation where JSCLC is the current density, ε0 is the
permittivity of space, εR is the dielectric constant of the polymer (assumed to be 3), μ is the zero-
field mobility of the majority charge carriers, V is the effective voltage across the device (V =
Vapplied – Vbi – Vr), and L is the polymer layer thickness:
𝐽 𝑆 𝐶𝐿𝐶 =
9
8
∙ 𝜀 𝑅 ∙ 𝜀 0
∙ 𝜇 ∙
𝑉 2
𝐿 3

The series and contact resistance of the hole-only device was measured using a blank
(ITO/PEDOT/Al) configuration and the voltage drop due to this resistance (Vr) was subtracted
from the applied voltage. The built-in voltage (Vbi), which is based on the relative work function
difference of the two electrodes, was also subtracted from the applied voltage. The built-in voltage
can be determined from the transition between the ohmic region and the SCL region and is found
to be about 1 V. Polymer film thicknesses were measured using a Film-Sense FS-1 Ellipsometer
and the Film-Sense FS-1 analysis software version 1.59 in Single Measurement mode using the
Cauchy on Si with k3 model as the average of five measurements across the slides.
192

B.2 Synthetic Procedures
Synthetic procedures for the synthesis of 9-(2-bromoethyl)-9H-carbazole was used without
modifications as reported in literature.
1
Toluene, and 1,1-diphenylethylene were freshly distilled
from CaH2 and were stored over 3Å sieves. Carbazole, 3-ethylhexylthiophene and 3,6-
dibromocarbazole were purchased from commercial sources and used as received.
Synthesis of 9-(2-azidoethyl)-9H-carbazole:

An oven dried three-neck flask was vacuum backfilled three times and charged with 1.00 g
(3.65 mmol, 1.00 eq.) of 9-(2-bromoethyl)-9H-carbazole and 1.42 g (21.88 mmol, 6.00 eq.) of
sodium azide. 30 mL DMF were added and the resulting mixture was heated to 80 °C overnight.
Upon cooling to RT, the mixture was poured into 350 mL H2O and the precipitate filtered off.
Washing the precipitate with additional water and drying it under high vacuum afforded the desired
product as a light brown solid in 98% yield (847.7 mg).
1
H-NMR (400 MHz, Chloroform-d): δ =
8.08 (d, 2H), 7.44 (m, 4H), 7.23 (m, 2H), 4.47 (t, 2H), 3.71 (t, 2H).

193

Synthesis of 6-(9H-carbazol-9-yl)hexan-1-ol:

An oven dried three-neck flask was vacuum backfilled three times and charged with 2.00 g
carbazole (11.96 mmol, 1.00 eq.) and 2.01 g potassium hydroxide (35.88 mmol, 3.00 eq.). 40 mL
DMF were added, and the resulting mixture was stirred at RT for 1 h. 2.03 mL 6-Bromo-1-hexanol
(2.82 g, 15.55 mmol, 1.30 eq.) were added dropwise and the mixture was heated to 65 °C overnight.
Upon cooling to the mixture was poured into 70 mL H2O, the aqueous solution was extracted with
EtOAc (3 × 70 mL), washed with H2O (4 × 150 mL), dried over MgSO4, filtered and concentrated
in vacuo. Purification of the crude product via column chromatography (hexanes/EtOAc = 60:40)
afforded the desired product as an off-white solid in 94% yield (2.45 g).
1
H-NMR (400 MHz,
Chloroform-d): δ = 8.11 (d, 2H), 7.44 (m, 4H), 7.23 (m, 2H), 4.32 (t, 2H), 3.60 (q, 2H), 1.90 (p,
2H), 1.54 (m, 2H), 1.41 (m, 4H).

194

Synthesis of 9-(6-bromohexyl)-9H-carbazole:

An oven dried three-neck flask was vacuum backfilled three times and charged with 3.20 g 6-
(9H-carbazol-9-yl)hexan-1-ol (11.96 mmol, 1.00 eq.) and 4.71 g triphenylphosphine (17.94 mmol,
1.50 eq.). 20 mL THF were added and the resulting mixture was cooled to 0°C. A second oven
dried three-neck flask was charged with 4.96 g of carbon tetrabromine (14.95 mmol, 1.25 eq.) and
20 mL THF. This solution was added dropwise at 0°C and the resulting mixture was stirred at 0
°C for another two hours before being warmed up to room temperature overnight. The reaction
solvent was removed in vacuo and the crude solid was redissolved in DCM. The organic phase
was washed with 10% NaOH(aq.) (1 × 70 mL) and H2O (2 × 70 mL), dried over MgSO4, filtered
and concentrated in vacuo. Purification of the crude product via column chromatography
(hexanes/DCM = 85:15) afforded the desired product as an off-white solid in 79% yield (3.12 g).
1
H-NMR (400 MHz, Chloroform-d): δ = 8.11 (d, 2H), 7.44 (m, 4H), 7.26 (m, 2H), 4.32 (t, 2H),
3.36 (t, 2H), 1.91 (p, 2H), 1.81 (p, 2H), 1.45 (m, 4H).

195

Synthesis of 9-(6-azidohexyl)-9H-carbazole:

An oven dried three-neck flask was vacuum backfilled three times and charged with 1.00 g
(3.65 mmol, 1.00 eq.) of 9-(6-bromohexyl)-9H-carbazole and 1.42 g (21.88 mmol, 6.00 eq.) of
sodium azide. 30 mL DMF were added and the resulting mixture was heated to 80 °C overnight.
Upon cooling to RT, the mixture was poured into 350 mL H2O and the precipitate filtered off.
Washing the precipitate with additional water and drying it under high vacuum afforded the desired
product as a light brown solid in 98% yield (847.7 mg).
1
H-NMR (400 MHz, Chloroform-d): δ =
8.11 (d, 2H), 7.45 (m, 4H), 7.26 (m, 2H), 4.32 (t, 2H), 3.22 (t, 2H), 1.90 (p, 2H), 1.55, (m, 2H),
1.41 (m, 4H).

196

Synthesis of (4-(2-ethylhexyl)thiophene-2-yl)trimethylstannane:

An oven dried three-neck flask was flame-dried three times and charged with 10 mL THF and
2.50 g 3-ethylhexylthiophene (12.73 mmol, 1.00 eq.) and cooled to -78 °C. 9.15 mL 1.6 M n-BuLi
(937.91 mg, 14.64 mmol, 1.15 eq.) were added dropwise, the resulting mixture was stirred at -78
°C for 1 h and then allowed to warm up to RT followed by stirred at RT for 30 min. A second oven
dried three-neck flask was flame-dried three times and charged with 40 mL THF and 14.90 mL 1
M SnMe3Cl (2.97 g, 14.90 mmol, 1.17 eq.). Upon cooling the initial flask back down to -78 °C,
the SnMe3Cl-solution was added dropwise. The resulting mixture was stirred at -78 °C for 1 h and
then warmed up to RT overnight before being poured into 150 mL H2O. The aqueous mixture was
extracted with hexane (3 × 150 mL), dried over MgSO4, filtered and concentrated in vacuo.
Purification of the crude product via vacuum distillation afforded the desired product as a clear,
colorless oil in 88% yield (4.02 g).
1
H-NMR (400 MHz, Chloroform-d): δ = 7.16 (d, 1H), 6.96 (d,
1H), 2.58 (d, 2H), 1.56 (m, 1H), 1.28 (m, 8H), 0.88 (m, 6H), 0.35 (s, 9H).
Synthesis of 6-(3,6-dibromo-9H-carbazol-9-yl)hexan-1-ol:

197

An oven dried three-neck flask was vacuum backfilled three times and charged with 2.00 g
3,6-dibromocarbazole (6.15 mmol, 1.00 eq.) and 1.04 g potassium hydroxide (18.46 mmol, 3.00
eq.). 40 mL DMF were added, and the resulting mixture was stirred at RT for 1 h. 1.05 mL 6-
Bromo-1-hexanol (1.45 g, 8.00 mmol, 1.30 eq.) were added dropwise and the mixture was heated
to 65 °C overnight. Upon cooling to the mixture was poured into 70 mL H2O, the aqueous solution
was extracted with EtOAc (3 × 70 mL), washed with H2O (4 × 100 mL), dried over MgSO4, filtered
and concentrated in vacuo. Purification of the crude product via column chromatography
(hexanes/EtOAc = 60:40) afforded the desired product as a white solid in 94% yield (2.45 g).
1
H-
NMR (400 MHz, Chloroform-d): δ = 8.14 (s, 2H), 7.55 (m, 2H), 7.26 (m, 2H), 4.25 (t, 2H), 3.60
(q, 2H), 1.85 (p, 2H), 1.52 (m, 2H), 1.38 (m, 4H).

Synthesis of 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazolyl)hexan-1-ol:

An oven dried three-neck flask equipped with a condenser was vacuum backfilled three times
and charged with 2.50 g 6-(3,6-dibromo-9H-carbazol-9-yl)hexan-1-ol (5.88 mmol, 1.00 eq.) and
4.86 g (4-(2-ethylhexyl)thiophene-2-yl)trimethylstannane (13.52 mmol, 2.30 eq.). 70 mL THF
198

were added and the resulting mixture was degassed for 20 min. 339.75 mg
Tetrakis(triphenylphosphine)palladium(0) (0.29 mmol, 0.05 eq.) were added in, the mixture was
degassed for an additional 20 min and then heated to 75 °C for 72 h. Upon cooling to RT the
mixture was poured into 250 mL H2O, extracted with CHCl3 (3 × 120 mL), dried over MgSO4,
filtered and concentrated in vacuo. Purification of the crude product via column chromatography
(EtOAc/hexanes = 60:40) afforded the desired product as a yellow oil in 59% yield (2.27 g).
1
H-
NMR (400 MHz, Chloroform-d): δ = 8.32 (d, 2H), 7.72 (dd, 2H), 7.37 (d, 2H), 7.18 (s, 2H), 6.83
(s, 2H), 4.31 (t, 2H), 3.61 (q, 2H), 2.59 (d, 4H), 1.91 (m, 2H), 1.63 (m, 2H), 1.53 (m, 2H), 1.47-
1.25 (m, 20H), 1.04-0.87 (m, 12H).

Synthesis of 9-(bromohexyl)-3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazole:

An oven dried three-neck flask was vacuum backfilled three times and charged with 925.0 mg
6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazolyl)hexan-1-ol (1.41 mmol, 1.00 eq.) and
554.73 mg triphenylphosphine (2.11 mmol, 1.50 eq.). 10 mL THF were added and the resulting
mixture was cooled to 0°C. A second oven dried three-neck flask was charged with 548.48 mg of
carbon tetrabromine (1.76 mmol, 1.25 eq.) and 10 mL THF. This solution was added dropwise at
199

0°C and the resulting mixture was stirred at 0 °C for another two hours before being warmed up
to room temperature overnight. The reaction solvent was removed in vacuo and the crude solid
was redissolved in DCM. The organic phase was washed with 10% NaOH(aq.) (1 × 70 mL) and
H2O (2 × 70 mL), dried over MgSO4, filtered and concentrated in vacuo. Purification of the crude
product via column chromatography (100% hexanes to hexanes/DCM = 1:1) afforded the desired
product as an off-white solid in 99% yield (2.23 g).
1
H-NMR (400 MHz, Chloroform-d): δ = 8.32
(s, 2H), 7.72 (dd, 2H), 7.37 (d, 2H), 7.18 (s, 2H), 6.83 (s, 2H), 4.32 (t, 2H), 3.37 (t, 2H), 2.59 (d,
4H), 1.92 (q, 2H), 1.83 (q, 2H), 1.64 (m, 2H), 1.48 (m, 2H), 1.44-1.22 (m, 18H), 0.94-0.83 (m,
12H).

Synthesis of 9-(6-azidohexyl)-3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazole:

An oven dried three-neck flask was vacuum backfilled three times and charged with 1.01 g
(1.40 mmol, 1.00 eq.) of 9-(bromohexyl)-3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazole
and 546.09 mg (8.40 mmol, 6.00 eq.) of sodium azide. 20 mL DMF were added and the resulting
mixture was heated to 80 °C overnight. Upon cooling to RT, the mixture was poured into 350 mL
H2O. The aqueous mixture was extracted with CHCl3 (3 × 200 mL), dried over MgSO4, filtered
200

and concentrated in vacuo affording the desired product as a brown oil in 83% yield (791.8 mg).
1
H-NMR (400 MHz, Chloroform-d): δ = 8.33 (s, 2H), 7.72 (dd, 2H), 7.36 (d, 2H), 7.18 (s, 2H),
6.83 (s, 2H), 4.31 (t, 2H), 3.22 (t, 2H), 2.59 (d, 4H), 1.91 (q, 2H), 1.64 (q, 2H), 1.55 (2H), 1.43-
1.25 (m, 20H), 0.95-0.85 (m, 12H).

Synthesis of 3-(trimethylsilyl)-prop-2-yn-1-yl methacrylate:

An oven dried three-neck flask equipped with an addition funnel was flame-dried three times
and charged with 4.77 mL (4.12 g, 32.15 mmol, 0.84 eq.) of trimethylsilyl propyn-1-ol and 5.81
mL (4.22 g, 41.71 mmol, 1.09 eq.) of triethylamine. 40 mL Et2O were added and the resulting
mixture was cooled down to -20 °C overnight. A solution of 3.74 mL (4.00 g, 38.27 mmol, 1.00
eq.) methacryloyl chloride in 20 mL Et2O was added to the addition funnel and added dropwise to
the initial reaction mixture over the course of one hour. The resulting mixture was stirred at -20
°C for an additional 30 min and then warmed up to RT overnight. Ammonium salts in the mixture
were removed via vacuum filtration, the filtrate was concentrated in vacuo and purified by column
chromatography (hexane/Et2O = 50:1) affording the desired product as a clear, colorless liquid in
70% yield (5.28 g).
1
H-NMR (400 MHz, Chloroform-d): δ = 6.17 (s, 1H), 5.61 (t, 1H), 4.76 (d,
2H), 1.97 (m, 3H), 0.19 (s, 9H).

201

Polymerization of silyl-protected MMA to give P1:

An oven dried Schlenck-flask was flame dried three times and subsequently charger with
50 mL toluene. The mixture was degassed by three freeze pump thaw cycles. 9.00 µL 1,1-
diphenylethylene (9.01 mg, 0.05 mmol, 0.007 eq.) and 0.03 mL n-butyl lithium (1.6 M in hexanes)
(3.20 mg, 0.05 mmol, 0.007 eq.) were added and the mixture was stirred at room temperature for
90 minutes. Upon cooling of the reaction to -78 °C 1.47 g 3-(trimethylsilyl)-prop-2-yn-1-yl
methacrylate (7.50 mmol, 1.00 eq.) were added in dropwise. The mixture was stirred at -78 °C for
five hours and then gradually warmed up to room temperature overnight. After quenching of the
reaction via addition of 1 mL MeOH the solvents were removed in vacuo. The crude solid was
redissolved in CHCl3, precipitated into 200 mL cold MeOH, filtered and dried under high-vacuum
yielding the desired product as a white solid in 53% yield (776.5 mg).
202

Figure B1:
1
H-NMR (CDCl3, 25°C, 500 MHz) of P1.

Deprotection of silyl-protected P1 to give P2:

An oven dried Schlenck-flask was flame dried three times and charged with 500.0 mg
Poly(TMS-alkyne-MMA) (2.55 mmol, 1.00 eq.) and 1.11 g potassium carbonate (8.03 g, 3.15 eq.).
Subsequently 20 mL of THF and 5 mL of MeOH were added into the flask which was then stirred
at RT overnight. The mixture was precipitated into 200 mL cold hexane, filtered and washed with
HCl(aq.), H2O and MeOH and finally dried under high-vacuum yielding the desired product as a
white solid in 77% yield (244.8 mg).
203

Figure B.2:
1
H-NMR (CDCl3, 25°C, 500 MHz) of P2.

Figure B.3:
13
C-NMR (CDCl3, 25°C, 600 MHz) of P2.

204

General procedure for Copper-catalyzed click reaction to give P3-P5:

An oven dried Schlenck-flask was flame dried three times, charged with 65.0 mg of alkyne-
PMMA polymer (0.52 mmol, 1.00 eq.) and the respective azide (0.62 mmol, 1.20 eq.) and vacuum
backfilled once more. 9.09 mg (N,N,N′,N′′,N′′-pentamethyldiethylenetriamine) (0.053 mmol,
0.10 eq.) and 12 mL THF were added and the mixture was degassed by three freeze pump thaw
cycles. 7.46 mg CuBr (0.052 mmol, 0.10 eq.) were added in and the resulting mixture was stirred
at RT overnight. The mixture was run over a short pad of silica which was washed with CHCl3.
The solution was concentrated in vacuo, precipitated into 200 mL cold MeOH, filtered and dried
under high vacuum to afford the desired product.

205

B.3 Characterization of Polymers
Table B.1 Characterization data for P1.
Polymer Mn [kg/mol] Đ Yield [%]
Tacticity
(mm/mr/rr)
P1 35.722 2.86 53 83/13/4

Table B.2 Characterization data for functionalized polymers P3-P5 after click reaction.
Polymer Conversion [%] Mn [kg/mol] Đ
P3 >99 38.641 5.46
P4 >99 71.595 3.43
P5 >99 38.838 2.08

Determination of tacticities as shown for polymer 2:
Tacticities were determined using the three distinct
1
H-NMR peaks for the methyl-group a in
the backbone of the parent poly(propargyl methacrylate) P2 for the three triad tacticities mm,
mr/rm and rr with mm being the peak corresponding to an isotactic environment for the methyl
groups consistent with the established literature on the same stereoregular polymer.
1
206

1
H-NMR of Polymers:

Figure B.4:
1
H-NMR (CDCl3, 25°C, 500 MHz) of P3.
207

Figure B.5:
13
C-NMR (CDCl3, 25°C, 600 MHz) pf P3.

Figure B.6:
1
H-NMR (CDCl3, 25°C, 500 MHz) of P4.
208

Figure B.7:
13
C-NMR (CDCl3, 25°C, 600 MHz) of P4.

Figure B.8:
1
H-NMR (CDCl3, 25°C, 500 MHz) of P5.
209

Figure B.9:
13
C-NMR (CDCl3, 25°C, 600 MHz) of P5.

210

Full functionalization of polymer P2 to give P3-P5 followed through
13
C-NMR:

P2

P3

P4

P5
211

B.4 Failed Post-Polymerization Functionalizations
Attempted post-polymerization functionalization with the 3,6-bis(4-(2-
ethylhexyl)thiophen-2-yl)carbazole pendant group via transesterification and thiol-ene
reactions:
For all functionalization methodologies discussed in the following with the exception of the
Sc(OTf)3 catalyzed thiol-ene click reaction successful quantitative functionalization of the
respective polymers with unsubstituted 2-(9H-carbazol-9-yl)ethan-1-ol or 2-(9H-carbazol-9-
yl)ethane-1-thiol respectively as a model system was confirmed prior to the attempted
functionalizations with 3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)carbazole. The
1
H-NMR spectra of
the various functionalizations with the model compounds are depicted alongside the spectra of the
failed functionalizations with 3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)carbazole below.

Transesterification with Ti(O
i
Pr)4:

212

An oven dried Schlenck-flask was flame dried three times, charged with 26.0 mg of
poly(methyl acrylate) (0.30 mmol, 1.00 eq.) and vacuum backfilled. 300.0 mg 6-(3,6-bis(4-(2-
ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)hexan-1-ol (0.56 mmol, 1.50 eq.), 8.53 mg Ti(O
i
Pr)4
(0.03 mmol, 0.10 eq.) and 3.00 mL dry toluene were added to the mixture. The Schlenck-flask was
then connected to a Dean-Stark apparatus that was equipped with 4 Å molecular sieves and placed
in a preheated oil-bath at 130 °C for 72 hours. Upon cooling to RT, the reaction mixture was
precipitated into 100 mL cold MeOH, the precipitating solids were filtered off, dried under high-
vacuum and analyzed via
1
H-NMR spectroscopy revealing only partial functionalization of the
polymer which in the case of functionalization by transesterification is evident by the presence of
an additional peak ~ 3.60 ppm stemming from the methyl group of unreacted methyl acrylate
moieties in the polymer (indicated with a green arrow in Fig. S10). The degree of functionalization
can be estimated from the relative integrations of this residual methyl peak and the adjacent peaks
at 4.30 ppm and 4.03 ppm corresponding to the -CH2- in the spacer that are bound to the nitrogen
atom of the carbazole and the oxygen atom of the ester moiety respectively as shown in Figure
S10 and was found to be 44%.

213

Figure B.10:
1
H-NMR (CDCl3, 25°C, 500 MHz) of Ti(O
i
Pr)4 catalyzed transesterification
of poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-
yl)hexan-1-ol.
Increasing the reaction time from 72 hours to 7 days only marginally increased the degree of
functionalization of the polymer to 46% while changing the solvent to o-DCB decreased the degree
of functionalization to 32%.
214

Figure B.11:
1
H-NMR (CDCl3, 25°C, 500 MHz) of Ti(O
i
Pr)4 catalyzed transesterification of
poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)hexan-1-
ol with a reaction time of 7 days.

215

Figure B.12:
1
H-NMR (CDCl3, 25°C, 500 MHz) of Ti(O
i
Pr)4 catalyzed transesterification of
poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)hexan-1-
ol with o-DCB as the solvent.

216

Figure B.13:
1
H-NMR (CDCl3, 25°C, 500 MHz) of Ti(O
i
Pr)4 catalyzed transesterification of
poly(methyl acrylate) with 2-(9H-carbazol-9-yl)ethan-1-ol.

Transesterification with ZnTAC24:

217

An oven dried Schlenck-flask was flame dried three times, charged with 26.0 mg of
poly(methyl acrylate) (0.30 mmol, 1.00 eq.) and vacuum backfilled. 258.0 mg 6-(3,6-bis(4-(2-
ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)hexan-1-ol (0.39 mmol, 1.30 eq.), 7.33 mg 4-
dimethylaminopyridine (0.06 mmol, 0.20 eq.), 3.58 mg ZnTAC24 (3.75 μmol, 0.0125 eq.) and
4.00 mL dry toluene were added to the mixture. The Schlenck-flask was then connected to a Dean-
Stark apparatus that was equipped with 4 Å molecular sieves and placed in a preheated oil-bath at
130 °C for 72 hours. Upon cooling to RT, the reaction mixture was precipitated into 100 mL cold
MeOH, the precipitating solids were filtered off, dried under high-vacuum and analyzed via
1
H-
NMR spectroscopy revealing only partial functionalization of the polymer. The degree of
functionalization was 7%.

Figure B.14:
1
H-NMR (CDCl3, 25°C, 500 MHz) of ZnTAC24 catalyzed transesterification of
poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)hexan-1-
ol.
218

Increasing the equivalents of the alcohol to 1.50 eq. and the catalyst loading to 3 mol-% did
not improve the outcome of the reaction and resulted in a degree of functionalization of 8%.

Figure B.15:
1
H-NMR (CDCl3, 25°C, 500 MHz) of ZnTAC24 catalyzed transesterification of
poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)hexan-1-
ol with increased catalyst loading and increased equivalents of the alcohol.
219

Figure B.16:
1
H-NMR (CDCl3, 25°C, 500 MHz) of ZnTAC24 catalyzed transesterification of
poly(methyl acrylate) with 2-(9H-carbazol-9-yl)ethan-1-ol.

Transesterification with TBD:

220

An oven dried Schlenck-flask was flame dried three times, charged with 26.0 mg of
poly(methyl acrylate) (0.30 mmol, 1.00 eq.) and vacuum backfilled. 300.0 mg 6-(3,6-bis(4-(2-
ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)hexan-1-ol (0.56 mmol, 1.50 eq.), 8.49 mg 1,5,7-
triazabicyclo[4.4.0]dec-5-ene (0.06 mmol, 0.20 eq.) and 3.00 mL dry toluene were added to the
mixture. The Schlenck-flask was then connected to a Dean-Stark apparatus that was equipped with
4 Å molecular sieves and placed in a preheated oil-bath at 130 °C for 72 hours. Upon cooling to
RT, the reaction mixture was precipitated into 100 mL cold MeOH, the precipitating solids were
filtered off, dried under high-vacuum and analyzed via
1
H-NMR spectroscopy revealing only
partial functionalization of the polymer. The degree of functionalization was 19%.

Figure B.17:
1
H-NMR (CDCl3, 25°C, 500 MHz) of TBD catalyzed transesterification of
poly(methyl acrylate) with 6-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)hexan-1-
ol.
221

Figure B.18:
1
H-NMR (CDCl3, 25°C, 500 MHz) of TBD catalyzed transesterification of
poly(methyl acrylate) with 2-(9H-carbazol-9-yl)ethan-1-ol.
Photochemical thiol-ene reaction:

222

An oven dried Schlenck-flask was flame dried three times, charged with 11.2 mg of poly(allyl
methacrylate) (0.09 mmol, 1.00 eq.) and vacuum backfilled. 5 mL of dry toluene were added in
and the mixture was degassed via three freeze pump-thaw cycles. The mixture was then heated up
to 90 °C until all the polymer was dissolved. After cooling to RT 219.0 mg 2-(3,6-bis(4-(2-
ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)ethane-1-thiol (0.36 mmol, 4.00 eq.) and 11.37 mg of
the photoinitiator 2,2-dimethoxy-2-phenylacetophenone (0.04 mmol, 0.50 eq.) were added in and
the resulting mixture was stirred in the dark under irradiation by a 300 nm UV LED lamp for 24
hours. The mixture was then precipitated into 170 mL cold MeOH, the solids were filtered off,
dried under high-vacuum and analyzed via
1
H-NMR spectroscopy revealing virtually no
functionalization of the polymer. In these thiol-ene reactions partial functionalization can be
confirmed through the presence of residual proton signals of the terminal double bond of unreacted
allyl moieties at 5.95 ppm and 5.32 ppm (indicated with green arrows in Figure S19). The degree
of functionalization can be estimated from the relative integrations of these residual allyl peaks
and the adjacent peaks around 4.60 ppm 3.80 and ppm corresponding to the -CH2- in the spacer
that are bound to the nitrogen atom of the carbazole and the oxygen atom of the ester moiety
respectively (see Figure S20). In Figure S19 no visible peaks for the spacer could be observed so
the degree of functionalization was assumed to be <1%.
223

Figure B.19:
1
H-NMR (CDCl3, 25°C, 500 MHz) of DMPA catalyzed thiol-ene reaction of
poly(allyl methacrylate) with 2-(3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)ethane-
1-thiol.

224

Figure B.20:
1
H-NMR (CDCl3, 25°C, 500 MHz) of DMPA catalyzed thiol-ene reaction of
poly(allyl methacrylate) with 2-(9H-carbazol-9-yl)ethane-1-thiol.
Scandium catalyzed thiol-ene reaction:
For the attempted thiol-ene post-polymerization functionalizations with a Sc(OTf)3 described
in the following, 9H-carbazoly-ethane-1-thiol was used instead of 2-(3,6-bis(4-(2-
ethylhexyl)thiophen-2-yl)-9H-carbazol-9-yl)ethane-1-thiol as the thiol-functionalized carbazole
compound. Unfunctionalized carbazoles with terminally functionalized ethyl-chains were in fact
the initial model systems for all post-polymerization functionalizations discussed here to confirm
that these are efficient methodologies for fully functionalizing our polymers with such simple
pendant groups. For all previously presented methodologies quantitative functionalization could
be achieved with the simple pendant groups which allowed us to conclude that the unsuccessful
functionalizations with our extended pendant group, 3,6-bis(4-(2-ethylhexyl)thiophen-2-yl)-
carbazole, are the result of incompatibility of these methodologies with such an extended group an
225

not the result of an ineffective procedure for quantitative post-polymerization functionalization. In
the case of the Sc(OTf)3 catalyzed thiol-ene reactions however we could not even achieve
quantitative functionalization of the polymer with the simple carbazole group and therefore
functionalization with the extended pendant group was not attempted.

An oven dried Schlenck-flask was flame dried three times, charged with 40.0 mg of poly(allyl
methacrylate) (0.32 mmol, 1.00 eq.) and vacuum backfilled. 3 mL of dry toluene were added in
and the mixture was heated up to 90 °C until all the polymer was dissolved. After cooling to RT
216.2 mg 9H-carbazoly-ethane-1-thiol (0.95 mmol, 3.00 eq.) and 4.68 mg of Scandium(III) triflate
(9.50 μmol, 0.03 eq.) were added in and the resulting mixture was submerged in a preheated oil
bath at 80 °C for 24 hours. After cooling to RT, the mixture was then precipitated into 125 mL
cold MeOH, the solids were filtered off, dried under high-vacuum and analyzed via
1
H-NMR
spectroscopy revealing only partial functionalization of the polymer.
226

Figure B.21:
1
H-NMR (CDCl3, 25°C, 500 MHz) of Sc(OTf)3 catalyzed thiol-ene reaction of
poly(allyl methacrylate) with 9H-carbazolyl-ethane-1-thiol.
Raising the reaction temperature to 100 °C while increasing the reaction time to 5 days did not
improve the outcome of the reaction. Neither did an additional increased in the catalyst loading to
40 mol-%.
227

Figure B.22:
1
H-NMR (CDCl3, 25°C, 500 MHz) of Sc(OTf)3 catalyzed thiol-ene reaction of
poly(allyl methacrylate) with 9H-carbazolyl-ethane-1-thiol with an increased reaction temperature
of 100 °C and an increased reaction time of 5 days.

228

Figure B.23:
1
H-NMR (CDCl3, 25°C, 500 MHz) of Sc(OTf)3 catalyzed thiol-ene reaction of
poly(allyl methacrylate) with 9H-carbazolyl-ethane-1-thiol with an increased reaction temperature
of 100 °C, an increased reaction time of 5 days and an increased catalyst loading of 40 mol-%.

B.5 GPC Traces
For the parent polymer P1 and the polymers functionalized with unsubstituted carbazole, P3
and P4, the GPC traces show negative refractive indices which is in agreement with our previously
reported findings for non-conjugated poly(allyl methacrylate) parent polymers and their
derivatives after functionalization with carbazole pendants, poly((N-carbazolylethylthio)propyl
methacrylates).
2,3

229

Figure B.24: GPC trace of P1 with Mn = 35.72 kg/mol and Đ = 2.86.

Figure B.25: GPC trace of P3 with Mn = 38.64 kg/mol and Đ = 5.46.

230

Figure B.26: GPC trace of P4 Mn = 71.59 kg/mol and Đ = 3.43.

Figure B.27: GPC trace of P5 Mn = 38.84 kg/mol and Đ = 2.08.

B.6 Differential Scanning Calorimetry
All DSC traces show the same sharp feature at ~ 50 °C which is an artifact stemming from the
instrument and not the samples themselves.
231

Figure B.28: Differential scanning calorimeter trace of P3.

Figure B.29: Differential scanning calorimeter trace of P4.
232

Figure B.30: Differential scanning calorimeter trace of P5.

B.7 UV/Vis Spectroscopy

Figure B.31: UV/Vis-absorption spectra of as cast polymers.
233

Figure B.32: UV/Vis-absorption spectra of polymers after annealing at 150 °C for 30
min.

234

B.8 Photoluminescence Data

Figure B.33: PL emission spectra of as cast polymers.

Figure B.34: PL emission spectra of polymers after annealing at 150 °C for 30 min.
235

B.9 Mobility Data

Figure B.35: Representative current-voltage plots for P3 as-cast (black), after annealing at 150
°C (red) and after annealing at 210 °C (blue).

Figure B.36: Representative current-voltage plots for P4 as-cast (black), after annealing at 150
°C (red) and after annealing at 210 °C (blue).
236

Figure B.37: Representative current-voltage plots for P5 as-cast (black), after annealing at 150
°C (red) and after annealing at 210 °C (blue).
Table B.3 Hole mobilities μ h both unannealed and annealed at 150 °C and 210 °C for 30 min in
air and film thicknesses for all copolymers.
Polymer
μh, unannealed [cm
2
V
-1

s
-1
]
μh, annealed at 150 °C [cm
2
V
-1
s
-1
]
μh, annealed at 210 °C
[cm
2
V
-1
s
-1
]
Thickness [nm]
P3 5.44 ± 2.5 ∙ 10
-7
4.40 ± 1.0 ∙ 10
-6
5.26 ± 1.6 ∙ 10
-5
62.5
P4 7.15 ± 2.2 ∙ 10
-6
4.79 ± 1.6 ∙ 10
-5
7.22 ± 0.5 ∙ 10
-5
68.4
P5 3.06 ± 1.3 ∙ 10
-7
1.91 ± 0.9 ∙ 10
-6
5.20 ± 2.5 ∙ 10
-6
74.5

B.10 References
(1) Kitaura, T.; Tomioka, H.; Fukatani, N.; Kitayama, T. Anchimeric assistance on
sequence regulations in partial modification of isotactic poly(propargyl methacrylate) by click
reaction. Polym. Chem., 2013, 4, 887-890.
(2) Samal, S.; Schmitt, A.; Thompson, B. C. Contrasting the Charge Carrier Mobility of
Isotactic, Syndiotactic, and Atactic Poly((N-carbazolylethylthio)propyl methacrylate). ACS Macro
Lett. 2021, 10 (12), 1493-1500.
237

(3) Schmitt, A.; Kazerouni, N.; Castillo, G. E.; Thompson, B. C. Synthesis of Block
Copolymers Containing Stereoregular Pendant Electroactive Blocks. ACS Macro. Lett. 2023, 12,
159-164.

238

Appendix C: Impact of Pendant Substituents on Post-Polymerization Functionalization
and Electronic Properties in Stereoregular Non-Conjugated Pendant Electroactive
Polymers

C.1 Materials and Methods
All reactions were performed under dry N2 in oven dried glassware, unless otherwise noted.
Unless noted otherwise, all reagents were purchased and used as received from commercial
sources though VWR. Solvents were purchased from VWR and used without purification, unless
otherwise noted. Toluene was dried over CaH2 before being distilled and stored over 3Å sieves.
THF was dried over sodium before distilled and stored over 3Å sieves.
All
1
H-NMR were recorded at 25 °C using CDCl3 on either a Varian Mercury 400 MHz, Varian
VNMRS-500 MHz, or a Varian VNMR-600 MHz. All spectra were referenced to CHCl3
(7.26 ppm), unless noted otherwise. Number average molecular weights (Mn) and dispersity (Ð)
were determined by size exclusion chromatography (SEC) on four 300 x 7.5 mm PL1110 Mixed
high grade organic columns (Agilent) at 140 °C using an Agilent PL-GPC separation module and
an Agilent 1260 Infinity II RI detector. All samples were dissolved in HPLC grade
trichlorobenzene at a concentration of 1.0 mg/mL, briefly heated and then allowed to cool to room
temperature prior to filtering through a 0.2 µm PTFE filter. The instrument was calibrated vs.
polystyrene standards (1050−3,800,000 g/mol), and data were analysed using Agilent GPC/SEC
software.
For polymer thin-film measurements, solutions were spin-coated onto pre-cleaned glass slides
from chloroform (CHCl3) solutions at 7 mg/mL. UV-Vis absorption spectra were obtained on a
239

PerkinElmer Lamda 950 spectrophotmeter. Photoluminescence (PL) measurements were
performed on a Photon Technology International QuantaMaster C-60 Spectrometer using the
Qm/Ex300 Em400 light source with an excitation wavelength of λ = 310 nm, a 5 mm slit-width, a
step-size of 2 nm and an integration of 0.5 seconds and analyzed using the Felix GX software.
The thicknesses of the thin films were obtained using a Film-Sense FS-1 Ellipsometer and the
Film-Sense FS-1 analysis software version 1.59 in Single Measurement mode using the Cauchy
on Si with k3 model as the average of five measurements across the slides.
Differential scanning calorimetry (DSC) profiles were recorded on a Perkin-Elmer DSC 8000
with a scan rate of 10 °C/min. The sample size was ~ 5 mg; polymers were used as obtained after
purification. The second cycle for each sample is depicted in Figure S18-S21 below. The
heating/cooling protocol used is:
1. Hold for 2.0 min at 20.0 °C
2. Heat from 20.0 °C to 250.0 °C at 10.0 °C/min
3. Cool from 250.0 °C to 20.0 °C at 10.0 °C/min
4. Heat from 20.0 °C to 250.0 °C at 10.0 °C/min
5. Cool from 250.0 °C to 20.0 °C at 10.0 °C/min

All DSC traces show the same sharp feature at ~ 50 °C which is an artifact stemming from the
instrument and not the samples themselves.
Mobility was measured using a hole-only device configuration of
ITO/PEDOT:PSS/Polymer/Al in the space charge limited current regime (SCLC). All steps of the
device fabrication and testing were performed in air. ITO-coated glass substrates (10 Ω/square,
Thin Film Devices Inc.) were subsequently cleaned by sonication in detergent, de-ionised water,
240

tetrachloroethylene, acetone and isopropyl alcohol and dried in a N2 stream. A thin layer of
PEDOT:PSS (Baytron® P VP Al 4083, filtered with a 0.45 μm PVDF syringe filter – Pall Life
Science) was first spin-coated on the pre-cleaned ITO-coated glass substrate and annealed at 130
°C for 60 minutes under vacuum. Polymer solutions were prepared in chloroform and stirred for
24 hours at 40 °C. The polymer active layer was spin-coated (with a 0.45 μm PTFE syringe filter
– Whatman) on top of the PEDOT:PSS layer. Films were placed in a nitrogen cabinet for 20
minutes before being transferred to a vacuum chamber. The substrates were pumped down to a
high vacuum and aluminium (100 nm) was thermally evaporated at 3-4 Å/s using an Angstrom
01353 Coating System onto the active layer through shadow masks to define the active area of the
devices. The dark current was measured under ambient conditions. At sufficient potential the
mobilities of charges in the device can be determined by fitting the dark current to the model of
SCL current and is described by the following equation where JSCLC is the current density, ε0 is the
permittivity of space, εR is the dielectric constant of the polymer (assumed to be 3), μ is the zero-
field mobility of the majority charge carriers, V is the effective voltage across the device (V =
Vapplied – Vbi – Vr), and L is the polymer layer thickness.
𝐽 𝑆 𝐶𝐿𝐶 =
9
8
∙ 𝜀 𝑅 ∙ 𝜀 0
∙ 𝜇 ∙
𝑉 2
𝐿 3

The series and contact resistance of the hole-only device was measured using a blank
(ITO/PEDOT/Al) configuration and the voltage drop due to this resistance (Vr) was subtracted
from the applied voltage. The built-in voltage (Vbi), which is based on the relative work function
difference of the two electrodes, was also subtracted from the applied voltage. The built-in voltage
can be determined from the transition between the ohmic region and the SCL region and is found
to be about 1 V. Polymer film thicknesses were measured using a Film-Sense FS-1 Ellipsometer
241

and the Film-Sense FS-1 analysis software version 1.59 in Single Measurement mode using the
Cauchy on Si with k3 model as the average of five measurements across the slides.
Simulations were carried out at the USC High Performance Computing Cluster (Discovery).
Discovery has over 400 compute nodes with 1200 cores of 2.60 GHz Xeon and 2.90 GHz EPYC
processors. All DFT calculations were done in 2.60 GHz Xeon processors using up to 128 Gb
memory.
C.2 Synthetic Procedures
Synthetic procedures for the synthesis of 2-(9H-carbazol-9-yl)ethanethiol were used without
modifications as reported in literature.
1
Toluene, THF, allyl methacrylate and 1,1-
diphenylethylene were freshly distilled from CaH2 and were stored over 3Å sieves. Carbazole, 3,6-
di(tbutyl)carbazole, 3,6-di(phenyl)carbazole, 3,6-di(methoxy)carbazole and 3,6-
di(bromo)carbazole were purchased from commercial sources and used as received without any
further purification.

242

Synthesis of 2-(3,6-disubstituted-9H-carbazol-9-yl)ethan-1-ol:

An oven dried three-neck flask equipped with a condenser was vacuum backfilled three times
and charged with the respective 3,6-disubstituted-9H-carbazole ethanol (1.00 eq.), ethylene
carbonate (1.50 eq.) and freshly ground potassium hydroxide (0.50 eq.). Dry DMF was added and
the reaction mixture subsequently heated to 170 °C overnight. After allowing the mixture to cool
to room temperature, the mixture was poured into H2O, extracted with EtOAc three times and
washed with H2O. The organic phase was dried over MgSO4, filtered and concentrated in vacuo.
Purification of the crude product via column chromatography (100% DCM) afforded the desired
products.
2-(3,6-di-tbutyl-9H-carbazol-9-yl)ethan-1-ol was afforded as a white solid in 65% yield.
1
H-
NMR (400 MHz, Chloroform-d): δ = 8.11 (d, 2H), 7.52 (dd, 2H), 7.37 (d, 2H), 4.44 (t, 2H), 4.06
(t, 2H), 1.46 (s, 18H).
2-(3,6-diphenyl-9H-carbazol-9-yl)ethan-1-ol was afforded as a white solid in 84% yield.
1
H-
NMR (400 MHz, Chloroform-d): δ = 8.37 (d, 2H), 7.74 (m, 6H), 7.55 (d, 2H), 7.48 (dt, 4H), 7.36
(dt, 2H), 4.55 (t, 2H), 4.13 (t, 2H).
243

2-(3,6-dimethoxy-9H-carbazol-9-yl)ethan-1-ol was afforded as a white solid in 80% yield.
1
H-
NMR (400 MHz, Chloroform-d): δ = 7.52 (d, 2H), 7.34 (d, 2H), 7.09 (dd, 2H), 4.41 (t, 2H), 4.03
(t, 2H), 3.93 (s, 6H).
Synthesis of 9-(2-bromoethyl)-3,6-disubstituted-9H-carbazole:

An oven dried three-neck flask was vacuum backfilled three times and charged with the
respective 2-(3,6-disubstituted-9H-carbazol-9-yl)ethan-1-ol (1.00 eq.) and triphenylphosphine
(1.50 eq.). Dry THF was added and the resulting mixture was cooled to 0°C. A second oven dried
three-neck flask was charged with carbon tetrabromine (1.25 eq.) and dry THF. This solution was
added dropwise at 0°C and the resulting mixture was stirred at 0 °C for another two hours before
being warmed up to room temperature overnight. The reaction solvent was removed in vacuo and
the crude solid was redissolved in DCM. The organic phase was washed with 10% NaOH(aq.) and
twice with H2O, dried over MgSO4, filtered and concentrated in vacuo. Purification of the crude
product via column chromatography (100% hexanes to hexanes/DCM = 1:1) afforded the desired
products.
9-(2-bromoethyl)-3,6-di-tbutyl-9H-carbazole was afforded as an off-white solid in 99% yield.
1
H-NMR (400 MHz, Chloroform-d): δ = 8.09 (d, 2H), 7.52 (d, 2H), 7.33 (d, 2H), 4.65 (t, 2H), 3.65
(t, 2H), 1.46 (s, 18H).
244

9-(2-bromoethyl)-3,6-diphenyl-9H-carbazole was afforded as an off-white solid in 99% yield.
1
H-NMR (400 MHz, Chloroform-d): δ = 8.36 (d, 2H), 7.74 (m, 6H), 7.50 (m, 6H), 7.36 (dt, 2H),
4.77 (t, 2H), 3.74 (t, 2H).
9-(2-bromoethyl)-3,6-dimethoxy-9H-carbazole was afforded as an off-white solid in 89%
yield.
1
H-NMR (400 MHz, Chloroform-d): δ = 7.52 (d, 2H), 7.30 (d, 2H), 7.10 (dd, 2H), 4.63 (t,
2H), 3.93 (s, 6H), 3.63 (t, 2H).
Synthesis of S-(2-(3,6-disubstituted-9H-carbazol-9-yl)ethyl) ethanthioate:

An oven dried three-neck flask equipped with a condenser was vacuum backfilled three times
and charged with potassium thioacetate (1.00 eq.), the respective 9-(2-bromoethyl)-3,6-
disubstituted-9H-carbazole (1.20 eq.) and tetrabutylammonium chloride (0.04 eq.). Dry THF was
added and the mixture was heated to 75 °C overnight. After cooling to room temperature, the
mixture was filtered, washed with EtOAc and the filtrate was concentrated in vacuo to afford the
crude product. Purification of the crude product via column chromatography (hexanes/DCM = 1:1)
afforded the desired products.
245

S-(2-(3,6-di-tbutyl-9H-carbazol-9-yl)ethyl) ethanthioate was afforded as a lightly orange solid
in 91% yield.
1
H-NMR (400 MHz, Chloroform-d): δ = 8.09 (d, 2H), 7.54 (dd, 2H), 7.43 (d, 2H),
4.41 (t, 2H), 3.24 (t, 2H), 2.41 (d, 3H), 1.46 (s, 18H).
S-(2-(3,6-diphenyl-9H-carbazol-9-yl)ethyl) ethanthioate was afforded as a lightly orange solid
in 70% yield.
1
H-NMR (400 MHz, Chloroform-d): δ = 8.36 (d, 2H), 7.75 (m, 6H), 7.61 (d, 2H),
7.49 (dt, 4H), 7.36 (dt, 2H), 4.52 (t, 2H), 3.32 (t, 2H), 2.43 (s, 3H).
S-(2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl) ethanthioate was afforded as a lightly orange
solid in 88% yield.
1
H-NMR (400 MHz, Chloroform-d): δ = 7.52 (d, 2H), 7.40 (d, 2H), 7.12 (dd,
2H), 4.39 (t, 2H), 3.94 (s, 6H), 3.22 (t, 2H), 2.93 (s, 3H).
Synthesis of 2-(3,6-disubstituted-9H-carbazol-9-yl)ethane-1-thiol:

An oven dried three-neck flask equipped with a condenser was vacuum backfilled three times
and charged with the respective S-(2-(3,6-disubstituted-9H-carbazol-9-yl)ethyl) ethanthioate
(1.00 eq.). Dry CHCl3 was added followed by the dropwise addition of 4-methylpiperidine
(3.00 eq.) and the resulting mixture was stirred at 60 °C overnight. After cooling to room
temperature, a few drops of EtOAc were added for quenching. The organic phase was washed
246

three times with H2O, dried over MgSO4, filtered and concentrated in vacuo. Purification of the
crude product via column chromatography (hexanes/DCM = 20:80) afforded the desired products.
2-(3,6-di-tbutyl-9H-carbazol-9-yl)ethane-1-thiol as afforded a white solid in 74% yield.
1
H-
NMR (400 MHz, Chloroform-d): δ = 8.10 (d, 2H), 7.52 (dd, 2H), 7.34 (d, 2H), 4.47 (t, 2H), 2.98
(q, 2H), 1.46 (s, 18H).
2-(3,6-diphenyl-9H-carbazol-9-yl)ethane-1-thiol as afforded a white solid in 85% yield.
1
H-
NMR (400 MHz, Chloroform-d): δ = 8.36 (d, 2H), 7.74 (m, 6H), 7.50 (m, 6H), 7.35 (dt, 2H), 4.58
(t, 2H), 3.06 (q, 2H), 1.46 (s, 1H).
2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol as afforded a white solid in 92% yield.
1
H-
NMR (400 MHz, Chloroform-d): δ = 7.52 (d, 2H), 7.31 (d, 2H), 7.10 (dd, 2H), 4.45 (t, 2H), 3.94
(s, 6H), 2.95 (q, 2H), 1.37 (t, 1H).
Synthesis of 9H-carbazole-3,6-dicarbonitrile:

An oven dried three-neck flask equipped with a condenser was charged with 3.00 g 3,6-
dibromocarbazole (9.23 mmol, 1.00 eq.) and 24.56 mg of 1,1'-bis(diphenylphosphino)ferrocene
(44.3 μmol, 0.005 eq.) and vacuum backfilled. 10 mL DMF and 0.1 mL H2O were added in and
the resulting mixtures was degassed for 45 min. After adding 1.30 g Zinc(II) cyanide (11.1 mg,
1.20 eq.), 24.12 mg Zinc powder (0.37 mmol, 0.04 eq.), 67.74 mg Zinc(II) acetate (0.37 mmol,
0.04 eq.) and 16.90 mg tris(dibenzylideneacetone)dipalladium(0) (18.5 μmol, 0.002 eq.), the
247

mixture was heated to 100 °C for 24 hours. Upon cooling to RT, the reaction mixture was poured
into 40 mL of an aqueous mixture of sat. NH4Cl/H2O/NH4OH (4:5:1). The precipitating solid was
collected via vacuum filtration and washed with another 40 mL of the same mixture, then with 50
mL H2O followed by toluene and finally MeOH affording the desired product as an off-white solid
in 99% yield (1.99 g).
1
H-NMR (400 MHz, DMSO-d6): δ = 12.37 (bs, 1H), 8.82 (d, 2H), 7.86 (dd,
2H), 7.73 (dd, 2H).
Synthesis of 9-(2-hydroxyethyl)-9H-carbazole-3,6-dicarbonitrile:

An oven dried three-neck flask equipped with a condenser was vacuum backfilled three times
and charged with 1.50 g 9H-carbazole-3,6-dicarbonitrile (6.91 mmol, 1.00 eq.), 912.11 mg
ethylene carbonate (10.36 mmol, 1.50 eq.) and 193.71 mg freshly ground potassium hydroxide
(3.45 mmol, 0.50 eq.). 15 mL DMF were added and the reaction mixture subsequently heated to
170 °C overnight. After allowing the mixture to cool to room temperature, the mixture was poured
into 60 mL H2O, extracted with EtOAc (3 × 70 mL) and washed with H2O (2 × 70 mL). The
organic phase was dried over MgSO4, filtered and concentrated in vacuo. Purification of the crude
product via column chromatography (100% EtOAc) afforded the desired product as an off-white
solid in 36% yield (657.9 mg).
1
H-NMR (400 MHz, Chloroform-d): δ = 8.43 (d, 2H), 7.80 (dd,
2H), 7.61 (d, 2H), 4.55 (t, 2H), 4.12 (t, 2H).

248

Synthesis of 2-(3,6-dicyano-9H-carbazol-9-yl)ethyl 4-methylbenzenesulfonate:

An oven dried three-neck flask was backfilled three times and charged 454.20 mg 4-
methylbenzenesulfonyl chloride (2.38 mmol, 1.50 eq.), 19.46 mg 4-dimethylaminopyridine
(0.16 mmol, 0.10 eq.) and 10 mL dry THF and subsequently cooled in an ice bath. At 0 °C
241.09 mg triethylamine (2.38 mmol, 1.50 eq.) and subsequently 415.9 mg 9-(2-hydroxyethyl)-
9H-carbazole-3,6-dicarbonitrile (1.59 mmol, 1.00 eq.) dissolved in 30 mL dry THF were added in
dropwise. After stirring at 0 °C the mixture was allowed to warm up to RT overnight. The mixture
was then diluted with EtOAc and the organic phase was washed with 1 M HCl(aq.) (1 × 50 mL) and
H2O (2 × 50 mL), dried over MgSO4, filtered and concentrated in vacuo. Purification of the crude
product via column chromatography (Hex/EtOAc = 60:40 to 100% EtOAc) afforded the desired
product as a white solid in 23% yield (181.6 mg).
1
H-NMR (400 MHz, Chloroform-d): δ = 8.35
(d, 2H), 7.76 (dd, 2H), 7.45 (d, 2H), 7.26 (d, 2H), 6.94 (d, 2H), 4.63 (t, 2H), 4.47 (t, 2H), 2.34 (s,
3H).

249

Synthesis of S-(2-(3,6-dicyano-9H-carbazol-9-yl)ethyl) ethanethioate:

An oven dried three-neck flask equipped with a condenser was vacuum backfilled three times
and charged with 45.0 mg potassium thioacetate (0.39 mmol, 1.00 eq.), 180.0 mg 2-(3,6-dicyano-
9H-carbazol-9-yl)ethyl 4-methylbenzenesulfonate (0.43 mmol, 1.10 eq.) and 4.38 mg
tetrabutylammonium chloride (16.0 μmol, 0.04 eq.). 3 mL THF were added and the mixture was
heated to 75 °C overnight. After cooling to room temperature the mixture was filtered, washed
with EtOAc and the filtrate was concentrated in vacuo to afford the crude product. Purification of
the crude product via column chromatography (hexanes/EtOAc = 40:60) afforded the desired
product as a light brown solid in 99% yield (125.3 mg).
1
H-NMR (400 MHz, Chloroform-d): δ =
8.42 (d, 2H), 7.83 (dd, 2H), 7.69 (d, 2H), 4.51 (t, 2H), 3.25 (t, 2H), 2.40 (s, 3H).
Synthesis of 9-(2-mercaptoethyl)-9H-carbazole-3,6-dicarbonitrile:

250

An oven dried three-neck flask equipped with a condenser was vacuum backfilled three times
and charged with 125.0 mg S-(2-(3,6-dicyano-9H-carbazol-9-yl)ethyl) ethanethioate (0.39 mmol,
1.00 eq.). 5 mL CHCl3 were added followed by the dropwise addition of 0.093 mL 4-
methylpiperidine (77.63 mg, 0.78 mmol, 2.00 eq.) and the resulting mixture was stirred at 45 °C
overnight. After cooling to room temperature the crude mixture was concentrated in vacuo.
Purification of the crude product via column chromatography (hexanes/EtOAc = 60:40) afforded
the desired product as a white solid in 74% yield (80.0 mg).
1
H-NMR (400 MHz, Chloroform-d):
δ = 8.42 (d, 2H), 7.81 (dd, 2H), 7.58 (d, 2H), 4.59 (t, 2H), 3.03 (q, 2H), 1.41 (s, 1H).
Synthesis of atactic poly(allyl methacrylate):

An oven dried Schlenck-flask was flame dried three times and subsequently charger with
45 mL toluene and 5 mL THF. The mixture was degassed by three freeze pump thaw cycles. 45.0
µL 1,1-diphenylethylene (45.06 mg, 0.25 mmol, 0.025 eq.) and 0.156 mL n-butyl lithium (1.6 M
in hexanes) (16.02 mg, 0.25 mmol, 0.025 eq.) were added and the mixture was stirred at room
temperature for 90 minutes. Upon cooling of the reaction to -78 °C 1.345 mL allyl methacrylate
(1.26 g, 10.0 mmol, 1.00 eq.) were added in dropwise. The mixture was stirred at -78 °C for two
hours and then gradually warmed up to room temperature overnight. After quenching of the
reaction via addition of 1 mL MeOH the solvents were removed in vacuo. The crude solid was
redissolved in CHCl3, precipitated into 200 mL cold MeOH, filtered and dried under high-vacuum
yielding the desired product as a sticky white solid in 54% yield (701.0 mg).
1
H-NMR (500 MHz,
251

Chloroform-d): δ = 5.91 (m, 1H), 5.28 (m, 2H), 4.47 (d, 2H), 1.48-2.22 (m, 2H), 0.83-1.29 (m,
3H).

Figure C.1:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of atactic PAMA.

Synthesis of isotactic poly(allyl methacrylate):

An oven dried Schlenck-flask was flame dried three times and subsequently charger with
50 mL toluene. The toluene was degassed by three freeze pump thaw cycles. 90.0 µL 1,1-
diphenylethylene (90.12 mg, 0.50 mmol, 0.05 eq.) and 0.302 mL n-butyl lithium (1.6 M in
252

hexanes) (32.04 mg, 0.50 mmol, 0.05 eq.) were added and the mixture was stirred at room
temperature for 90 minutes. Upon cooling of the reaction to -78 °C 1.345 mL allyl methacrylate
(1.26 g, 10.0 mmol, 1.00 eq.) were added in dropwise. The mixture was stirred at -78 °C for two
hours and then gradually warmed up to room temperature overnight. After quenching of the
reaction via addition of 1 mL MeOH the solvent was removed in vacuo. The crude solid was
redissolved in CHCl3, precipitated into 200 mL cold MeOH, filtered and dried under high-vacuum
yielding the desired product as a sticky white solid in 54% yield (701.0 mg).
1
H-NMR (500 MHz,
Chloroform-d): δ = 5.91 (m, 1H), 5.27 (m, 2H), 4.48 (d, 2H), 2.16 (m, 1H), 1.58 (m, 1H), 0.83-
1.29 (m, 3H).

Figure C.2:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of isotactic PAMA.

253

General procedure for thiol-ene click reactions:

An oven dried Schlenck-flask was flame dried three times and subsequently charged with
50 mg of PAMA polymer (0.396 mmol, 1.00 eq.). A separate oven dried Schlenck-flask was flame
dried three times and then charged with toluene which was degassed via three freeze pump thaw
cycles. 5 mL toluene were added to the polymer and the mixture was heated to 90 °C until all
polymer was dissolved. After cooling the mixture to room temperature 3.00 eq. of the respective
thiol and 50.79 mg 2,2-dimethoxy-2-phenylacetophenone (0.198 mmol, 0.50 eq.) were added in.
The resulting mixture was stirred under 300 nm UV LED light irradiation while covered at room
temperature overnight. After precipitating the mixture in 100 mL cold MeOH the solids were
filtered off and dried under high-vacuum affording the desired products

C.3 Polymer Characterization
All devices were fabricated and characterized An oven dried Schlenck-flask was flame dried
three times and subsequently charged with 50 mg of PAMA polymer (0.396 mmol, 1.00 eq.). A
separate oven dried Schlenck-flask was flame dried three times and then charged with toluene
254

which was degassed via three freeze pump thaw cycles. 5 mL toluene were added to the polymer
and the mixture was heated to 90 °C until all polymer was dissolved. After cooling the mixture to
room temperature 3.00 eq. of the respective thiol and 50.79 mg 2,2-dimethoxy-2-
phenylacetophenone (0.198 mmol, 0.50 eq.) were added in. The resulting mixture was stirred
under 300 nm UV LED light irradiation while covered at room temperature overnight. After
precipitating the mixture in 100 mL cold MeOH the solids were filtered off and dried under high-
vacuum affording the desired products.
Table C.1 Molecular weights, dispersities, yield and triad tacticities for parent PAMA
homopolymers.
Polymer Mn [kDa] Đ Yield [%] Triad Tacticity [mm/mr/rr]
ata PAMA 28.42 2.49 54 57/18/25
iso PAMA 49.74 1.73 29 86/11/3

Table C.2 Conversions, molecular weights and polydispersities for the functionalized
PCzETPMA polymers.
Polymer Conversion [%] Mn [kDa] PDI
tBuCz-ata >99 65.01 2.17
tBuCz-iso 98 66.92 2.98

Determination of tacticities as shown for iso PAMA:
Tacticities were determined using the three distinct
1
H-NMR peaks for the methyl-group a in
the backbone of the PAMA-block for the three triad tacticities mm, mr/rm and rr with mm being
the peak corresponding to an isotactic environment for the methyl groups as establish in a previous
study.
1

255

1
H-NMR of Polymers:

Figure C.3:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of tBuCz-ata.
256

Figure C.4:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of tBuCz-iso.

Figure C.5:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of Cz-ata.
257

Figure C.6:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of Cz-iso.

C.3 Attempted thiol-ene functionalizations with 2-(3,6-disubstituted-9H-carbazol-9-
yl)ethane-1-thiols for phenyl, methoxy and nitrile as the respective substituents:
a) Thiol-ene with 2-(3,6-diphenyl-9H-carbazol-9-yl)ethane-1-thiol
An oven dried Schlenck-flask was flame dried three times and subsequently charged with
50 mg of the atactic PAMA polymer (0.396 mmol, 1.00 eq.). A separate oven dried Schlenck-flask
was flame dried three times and then charged with toluene which was degassed via three freeze
pump thaw cycles. 30 mL toluene were added to the polymer and the mixture was heated to 90 °C
until all polymer was dissolved. After cooling the mixture to room temperature 3.00 eq. of 2-(3,6-
diphenyl-9H-carbazol-9-yl)ethane-1-thiol and 50.79 mg 2,2-dimethoxy-2-phenylacetophenone
(0.198 mmol, 0.50 eq.) were added in. The resulting mixture was stirred under 300 nm UV LED
258

light irradiation while covered at room temperature overnight. After precipitating the mixture in
100 mL cold MeOH the solids were filtered off, dried under high-vacuum analyzed by
1
H-NMR
spectroscopy.
For this reaction precipitation afforded virtually insoluble solids. Analysis by
1
H-NMR
spectroscopy did not show any peaks corresponding to the successfully functionalized product as
evident by the absence of any spacer peaks around 4.30 ppm 3.80 and ppm corresponding to the -
CH2- in the spacer that are bound to the nitrogen atom of the carbazole and the oxygen atom of the
ester moiety respectively. Unreacted PAMA starting material could also not be observed as evident
by the absence of residual proton signals of the terminal double bond of unreacted allyl moieties
at 5.95 ppm and 5.32 ppm. Considering the observed low solubility of 2-(3,6-diphenyl-9H-
carbazol-9-yl)ethane-1-thiol this could be due decreasing solubility of the polymer as the degree
of functionalized with this insoluble pendant group increases.
Analysis of the filtrate after precipitation and filtration by
1
H-NMR spectroscopy (Figure S8)
showed no residual 2-(3,6-diphenyl-9H-carbazol-9-yl)ethane-1-thiol and instead only the
photodimerized 1,2-bis(2-(3,6-diphenyl-9H-carbazol-9-yl)ethyl)disulfane clearly demonstrating
that significant photodimerization occurred as a side reaction in this thiol-ene reaction.
259

Figure C.7:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the solid filtrate of the thiol-ene
reaction of atactic PAMA with 2-(3,6-diphenyl-9H-carbazol-9-yl)ethane-1-thiol.

Figure C.8:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the filtrate after the thiol-ene
reaction of atactic PAMA with 2-(3,6-diphenyl-9H-carbazol-9-yl)ethane-1-thiol.
260

Figure C.9 shows the
1
H-NMR spectra of 1,2-bis(2-(3,6-diphenyl-9H-carbazol-9-
yl)ethyl)disulfane side by side. The dimerized product is characterized by the absence of the proton
signal at 1.46 ppm stemming from the thiol-group (indicated by a green arrow) as well as be a
distinct shift of the chemical shifts of the -CH2- groups of the spacer at 4.65 ppm and 3.16 ppm
(shown in the red box). Additionally, for the peak corresponding to the -CH2- group adjacent to
the thiol/disulfide moiety around 3 ppm, the multiplicity changes from a quartet in the case of the
thiol to a triplet in the case of the disulfide coupled side product (see red box).

Figure C.9:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of 2-(3,6-diphenyl-9H-carbazol-9-
yl)ethane-1-thiol (top) and the dimerized 1,2-bis(2-(3,6-diphenyl-9H-carbazol-9-
yl)ethyl)disulfane (bottom).

261

b) Thiol-ene with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol
General procedure:
An oven dried Schlenck-flask was flame dried three times and subsequently charged with the
atactic PAMA polymer (1.00 eq.). A separate oven dried Schlenck-flask was flame dried three
times and then charged with toluene which was degassed via three freeze pump thaw cycles. 5 mL
toluene were added to the polymer and the mixture was heated to 90 °C until all polymer was
dissolved. After cooling the mixture to room temperature the respective thiol and 2,2-dimethoxy-
2-phenylacetophenone were added in. The resulting mixture was stirred under 300 nm UV LED
light irradiation while covered. After precipitating the mixture in 100 mL cold MeOH the solids
were filtered off, dried under high-vacuum and analyzed by
1
H-NMR spectroscopy. In these thiol-
ene reactions partial functionalization can be confirmed through the presence of residual proton
signals of the terminal double bond of unreacted allyl moieties at 5.95 ppm and 5.32 ppm. The
degree of functionalization can be estimated from the relative integrations of these residual allyl
peaks and the adjacent peaks around 4.30 ppm 3.80 and ppm corresponding to the -CH2- in the
spacer that are bound to the nitrogen atom of the carbazole and the oxygen atom of the ester moiety
respectively.

262

Table C.3 Reaction conditions for the thiol-ene reactions of atactic PAMA with 2-(3,6-
dimethoxy-9H-carbazol-9-yl)ethane-1-thiol
Entry Eq. of thiol
DMPA loading [mol-
%]
Reaction time
[h]
Degree of functionalization
[%]
1 3.0 0.5 24 62
2 3.0 0.5 72 76
3 3.0 0.25 24 64
4 3.0 1.0 24 62
5
a
1.5 1.1 24 77
6
a
3.0 0.1 24 45
7
b
2.0 1.0 25 31
a
Irgacure 819 was used as the photocatalyst instead of DMPA.
b
A solution of PAMA in toluene was slowly
added dropwise to the mixture of the thiol and DMPA over 3h.

Figure C.10:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed in
Table C.3, entry 1.
263

Figure C.11:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed in
Table C.3, entry 2.

264

Figure C.12:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed in
Table C.3, entry 3.

265

Figure C.13:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed in
Table C.3, entry 4.

266

Figure C.14:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed in
Table C.3, entry 5.

267

Figure C.15:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed in
Table C.3, entry 6.

268

Figure C.16:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethane-1-thiol under the conditions listed in
Table C.3, entry 7.
c) Thiol-ene with 9-(2-mercaptoethyl)-9H-carbazole-3,6-dicarbonitrile
An oven dried Schlenck-flask was flame dried three times and subsequently charged with
50 mg of PAMA polymer (0.396 mmol, 1.00 eq.). A separate oven dried Schlenck-flask was flame
dried three times and then charged with toluene which was degassed via three freeze pump thaw
cycles. 5 mL toluene were added to the polymer and the mixture was heated to 90 °C until all
polymer was dissolved. After cooling the mixture to room temperature 3.00 eq. of 9-(2-
mercaptoethyl)-9H-carbazole-3,6-dicarbonitrile and 50.79 mg 2,2-dimethoxy-2-
phenylacetophenone (0.198 mmol, 0.50 eq.) were added in. The resulting mixture was stirred
under 300 nm UV LED light irradiation while covered at room temperature overnight. After
precipitating the mixture in 100 mL cold MeOH the solids were filtered off, dried under high-
269

vacuum analyzed by
1
H-NMR spectroscopy. Failure of the reaction was confirmed through
residual proton signals of the terminal double bond of unreacted allyl moieties at 5.95 ppm and
5.32 ppm as well as the absence of any peaks corresponding to the -CH2- in the spacer that are
bound to the nitrogen atom of the carbazole and the oxygen atom of the ester moiety respectively
around 4.60 ppm 3.80 and ppm (see Figure C.15).

Figure C.17:
1
H-NMR (CDCl3, 25°C, 500 MHz) spectra of the thiol-ene reaction of atactic
PAMA with 9-(2-mercaptoethyl)-9H-carbazole-3,6-dicarbonitrile.
C.4 Differential Scanning Calorimetry
All DSC traces show the same sharp feature at ~ 50 °C which is an artifact stemming from the
instrument and not the samples themselves.
270

Figure C.18: Differential scanning calorimeter trace of tBuCz-ata.

Figure C.19: Differential scanning calorimeter trace of tBuCz-iso.
271

Figure C.20: Differential scanning calorimeter trace of Cz-ata.

Figure C.21: Differential scanning calorimeter trace of Cz-iso.

272

C.5 UV/Vis Absorption Data

Figure C.22: UV/Vis-absorption spectra of as cast polymers.

Figure C.23: UV/Vis-absorption spectra of polymers after annealing at 150 °C for 30 min.
273

C.6 Photoluminescence Data

Figure C.24: PL emission spectra of as cast polymers.

Figure C25: PL emission spectra of polymers after annealing at 150 °C for 30 min.
274

C.7 Mobility Data
Table C.4 Hole mobilities μh both unannealed and annealed at 150 °C for 30 min in air
and film thicknesses for all polymers.
Polymer
μh, unannealed [cm
2
V
-1
s
-
1
]
μh, annealed [cm
2
V
-1
s
-1
] Thickness [nm]
tBuCz-ata 2.84 ± 0.4 ∙ 10
-6
2.96 ± 1.1 ∙ 10
-5
69.2
tBuCz-iso 1.03 ± 0.8 ∙ 10
-5
3.12 ± 0.2 ∙ 10
-5
69.6
Cz-ata 3.94 ± 1.3 ∙ 10
-5
8.72 ± 1.4 ∙ 10
-5
60.2
Cz-iso 5.04 ± 0.9 ∙ 10
-5
1.09 ± 0.3 ∙ 10
-4
55.7

C.8 Simulations
Using IQmol molecular builder, an initial starting conformation was developed for atactic and
isotactic polymers. These polymer chains were limited to 40 repeating units because of
computational limitations. Within IQmol itself, once the initial conformation was made, the initial
structure was optimized using Molecular Mechanics and MMFF94 force field. Once energy
optimization were done, using IQmol a Q-Chem input file was created for geometry optimization
using Hartree-Fock (HF) theory and the STO-6G basis set. Then the optimized geometry from
HF/STO-6G was taken and loaded into IQmol and another Q-Chem input file was created for
geometry optimization using DFT (B3LYP) and 6-31+G(d) basis set to obtain our final optimized
polymer chains.
275

Figure C26: Optimized structure for atactic tBuCz-polymer with 40 repeat units.

Figure C27: Optimized structure for isotactic tBuCz-polymer with 40 repeat units.
276

Figure C28: Optimized structure for atactic Cz-polymer with 40 repeat units. Reprinted with
Permission from Samal et al.
1
Copyright 2021 American Chemical Society.

Figure C29: Optimized structure for isotactic Cz-polymer with 40 repeat units. Reprinted with
Permission from Samal et al.
1
Copyright 2021 American Chemical Society.
277

C.9 References
(1) Samal, S.; Schmitt, A.; Thompson, B. C. Contrasting the Charge Carrier Mobility of
Isotactic, Syndiotactic, and Atactic Poly((N-Carbazolylethylthio)Propyl Methacrylate). ACS
Macro Lett. 2021, 10 (12), 1493–1500. https://doi.org/10.1021/acsmacrolett.1c00622.

Abstract (if available)

Abstract Over the last decades conjugated polymers (CPs) have gained increasing attention for the use in various organic electronics such as organic photovoltaics (OPVs), organic field effect transistors (OFETs), organic light emitting diodes (OLEDs), bioelectronics and electrochromics. The unique advantages associated with these organic polymers such a light weight, high flexibility, low costs, biocompatibility and the potential for easily scalable roll-to-roll processing make them a highly attractive alternative to more traditionally used, inorganic materials in (opto-)electronic devices. However, despite the significant advances made in the field of CPs which has resulted in a plethora of intricately designed polymers yielding record breaking devices performances, they still suffer from a number of critical limitations. CPs have significantly lower molecular weights and higher dispersities compared to established non-conjugated polymers while also exhibiting low environmental stability, very limited mechanical stability and low solubility. Additionally, the need for compatibility of the polymerization methodologies with fully conjugated monomers significantly restricts the suite of polymerization procedures available for the synthesis of CPs which generally do not allow for the synthesis of more complex, hierarchically ordered polymer structures or an efficient control over the polymer end groups.
A novel class of materials with the potential of overcoming these challenges without sacrificing the advantageous properties associated with CPs are non-conjugated electroactive pendant polymers (NCPEPs). NCPEPs are polymers with a fully non-conjugated backbone to which electroactive pendant groups are attached via spacers of fixed length and nature. Unlike CPs, they are compatible with the methodologies for highly controlled polymerizations established for non-conjugated polymers such as living radical, living ionic, ring opening or metallocene polymerizations. Additionally, these methodologies also allow for the synthesis of more complex electroactive polymer structures inlcuding block-copolymer, graft-polymers or star-shaped polymers. Although due to significant disorder and only limited π–π stacking, charge carrier mobilities of typical NCPEPs were orders of magnitude lower than in CPs, recent work in the field has demonstrated that through understanding of fundamental structure–property relationships in these NCPEP their structural parameters, most notably stereoregularity of the backbone and length of the spacer, can effectively be tuned leading to significantly improved charge carrier mobilities that even outperform certain well-established CPs.
In this dissertation such structure–property relationships are investigated for tuning of the polymer architecture and the nature of the pendant group. The complexity of the architecture of a NCPEP system was increased from homopolymers to block-copolymers and in separate NCPEP homopolymers the structure of the pendant group was extended to disubstituted carbazoles bearing conjugated thiophene and bulky alkyl substituents respectively. Along with the structural parameter, the compatibility of extended pendant groups with established post-polymerization methodologies is explored and new functionalization techniques are developed to synthesize functionalized NCPEPs with high charge carrier mobilities.

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Asset Metadata

Creator Schmitt, Alexander (author)

Core Title Synthesis of stereoregular non-conjugated pendant electroactive polymers

School College of Letters, Arts and Sciences

Degree Doctor of Philosophy

Degree Program Chemistry

Degree Conferral Date 2023-05

Publication Date 05/05/2024

Defense Date 05/01/2023

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag electroactive polymers,OAI-PMH Harvest,organic chemistry,organic synthesis,polymer chemistry

Format theses (aat)

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