Synthesis and Characterisation of some Electroactive Polymers Fang Chen B.Sc.

252 Pages·2013·4.52 MB·English

Synthesis and Characterisation of some Electroactive Polymers
Fang Chen B.Sc.(Hons.), M.Sc.
A thesis presented to Dublin City University
for the degree of Doctor in Philosophy
October 1992
This thesis is dedicated to my parents.
Acknowledgements
First and foremost I would like to express my sincere thanks to my supervisor
Professor Albert C. Pratt for his continuous help, encouragement, and advice
during the course of this work, also to Dr. Han Vos for his interest in my work
and advice with the electrochemistry.
I would also like to thank the School of Chemical Sciences for its financial
assistance and its staff and postgraduate students for their help and friendship
during the course of this work.
I'd like to express my gratitude to my wife, Bei Wu, for her persistent
encouragement, support and assistance.
Declaration
This thesis has not been submitted as an exercise for a degree at this or any
other University. Except as otherwise indicated, this work has been carried out
by the author alone.
Fang Chen
School of Chemical Sciences
Dublin City University
Abstract
In order to synthesise suitable starting materials for the synthesis of
electroactive monomers, the mono-methylation of some primary amines was
firstly investigated. This méthylation reaction involved a Mannich reaction of
primary amine with succinimide and formaldehyde followed by the reduction
using sodium borohydride in DMSO. This reaction was applied to
p-dimethylaminoaniline, p-diaminobenzene, o-diaminobenzene and
1 -aminoanthraquinone.
Three electroactive monomers, 2-(p-dimethylamino-N-methylarrilino)ethyl
methacrylate, 2-(p-dimethylamino-N-methylanilino)ethyl acrylate, and 4-(p-
dimethylamino-N-methylan ilino)butyl acrylate were synthesised through the
tosylation of certain hydroxy alkyl acrylates followed by nucleophilic substitution
with p-dimethylamino-N-methylaniline.
Homopolymers of the three electroactive monomers and copolymers of the
electroactive monomers with methyl acrylate and styrene, with different
compositions, were synthesised through free radical polymerizations. The
characterization of these polymers by NMR gave interesting stereochemical
informations of the polymer chain.
The electrochemical properties of these electroactive polymers were
investigated both in solution and in solid state (as modified electrodes) using
cyclic voltammetric experiments. According to the electrochemical behaviour of
these polymers in different conditions, some good electrolyte systems (TEAP or
Lithium perchlorate in propylene carbonate) and potential range (-0.3 to 0.5V
vs. SCE) were suggested for the applications of these polymers.
Contents
Title page i
Dedication ii
Acknowledgements iii
Declaration iv
Abstract v
Contents vi
Chapter I General introduction
1.1 Background 2
1.2 Electrically conductive polymers 3
1.2.1 Development of electrically conductive polymers 3
1.2.2 Synthesis and properties of polyacetylene 4
1.2.3 Synthesis and properties of polyaniline 9
1.2.4 Synthesis and properties of polypyrrole 10
1.2.5 Applications of conducting polymers 12
1.3 Donor-acceptor complexes 16
1.3.1 Introduction 16
1.3.2 Structure considerations 17
1.3.3 Synthesis of donors and acceptors 18
1.3.4 Polymeric charge transfer complexes 20
1.3.5 Applications of donor-acceptor complexes 21
1.4 Redox polymers 23
1.4.1 Introduction 23
1.4.2 Addition polymerisation 25
1.4.2.1 Vinylhydroquinone and derivatives and their polymers 25
1.4.2.2 Vinylferrocene 28
1.4.2.3 Viologen redox system 29
1.4.2.4 Dihydropyridine-pyridinium redox system 30
1.4.3 Step-growth polymerisation 31
1.4.4 Polymer modification 33
1.4.5 Applications of redox polymers 35
1.4.5.1 Reagents 37
1.4.5.2 Application in digital display devices 38
1.4.5.3 Photoredox processes in macromolecular assemblies 39
1.4.5.4 Electrocatalysis 40
vi
1.5 Background to the work described in this thesis 41
Chapter II Synthesis and Characterization of Monomers
2.1 Introduction 45
2.2 General synthetic approach 47
2.3 Monomethylation of amines 49
2.4 Results and discussion 51
2.4.1 Synthesis of p-dimethylamino-N-methylaniline 51
2.4.2 Méthylation of p-diaminobenzene 52
2.4.3 Synthesis and characterisation of N.N'-dimethyl-o- 54
diaminobenzene
2.4.4 Attempted méthylation of m-diaminobenzene 56
2.4.5 Méthylation of 1 -aminoanthraquinone 58
2.4.6 Synthesis and characterization of 2-(p-dimethylamino-N- 60
methylanilino)ethyl methacrylate
2.4.7 Synthesis and characterisation of monomer 2-(p- 63
dimethylamino-N-methylaniiino)ethyl acrylate
2.4.8 Synthesis and characterisation of 4-(p-dimethylamino-N- 66
methylanilino)butyl acrylate
2.4.9 Line broadening in the NMR spectra of the diaminobenzene 68
type monomers
2.4.10 Synthesis and characterisation of N-aryloyl-N-methyl-1- 76
aminoanthraquinone
2.4.11 Some other attempts to synthesize diaminobenzene type 76
nonomers
2.4.12 Investigations of the synthesis of some hydroquinone type 78
monomers
2.5 Experimental section 82
2.5.1 General experiments 82
2.5.2 Preparation of N-succinimidomethyl-p-dimethylaminoaniline 83
2.5.3 Preparation of N-methyl-p-dimethylaminoaniline 84
2.5.4 Preparation of N,N'-bis(succinimidomethyl)-p- 84
diaminobenzene
2.5.5 Acétylation of N,N'-bis(succinimidomethyl)-p-diaminobenzene 85
2.5.6 Preparation of N,N'-dimethyl-p-diaminobenzene 85
2.5.7 Preparation of N, N'-bis(succinimidomethyl)-o- 86
diaminobenzene
vii
2.5.8 Preparation of N.N'-dimethyl-o-diaminobenzene 87
2.5.9 Attempted synthesis of N, N'-bis(succinimidomethyl)-m- 88
diaminobenzene
2.5.10 Preparation of N-succinimidomethyl-1-aminoanthraquinone 89
2.5.11 Preparation of N-methyl-1-aminoanthraquinone 90
2.5.12 Tosylation of 2-hydroxyethyl methacrylate 91
2.5.13 Synthesis of 2-(p-dimethylamino-N-methylanilino)ethyl 91
methacrylate as its p-toluenesulphonic acid salt
2.5.14 Tosylation of 2-hydroxyethyl acrylate 93
2.5.15 Preparation of 2-(p-dimethylamino-N-methylanilino)ethyl 94
acrylate as its p-toluenesulphonic acid salt
2.5.16 Tosylation of 4-hydroxybutyl acrylate 95
2.5.17 Synthesis of 4-(p-dimethylamino-N-methylanilino)butyl 96
acrylate as its dinitrobenzoic acid salt
2.5.18 Synthesis of N-aryloyl-N-methyl-1 -aminoanthraquinone 97
2.5.19 Synthesis of 3-chloropropyl acrylate 98
2.5.20 Synthesis of 2-morpholinomethylhydroquinone 99
2.5.21 Synthesis of 2,5-bis(morpholinomethyl)hydroquinone 100
2.5.22 Synthesis of 2,5-bis(piperidinomethyl)hydroquinone 101
2.5.23 Attempted reactions with 2-morpholinomethylhydroquinone 102
Chapter III Synthesis and characterization of electroactive polymers
3.1 Introduction 105
3.1.1 Step-growth polymerization 105
3.1.2 Addition polymerization 107
3.1.2.1 Free radical initiation 107
3.1.2.2 Propagation 109
3.1.2.3 Termination 110
3.1.2.4 Ionic polymerization 112
3.1.2.5 Ziegler-Natta polymerisation 114
3.1.2.6 Group transfer polymerisation 115
3.1.2.7 Copolymerization 116
3.1.3 Molecular weight and molecular weight distribution 118
3.1.4 Gel permeation Chromatography 121
3.2 Results and discussion 124
3.2.1 Synthesis and characterisation of poly[2-(p-dimethylamino-N- 124
methy I an i I i no) ethyl m ethacry late]
viii
3.2.2 Synthesis and characterization of poly[2-(p-dimethylamino- 136
N-methylanilino)ethyl acrylate]
3.2.3 Synthesis and characterization of poly[4-(p-dimethylamino-N- 139
methylanilino)butyl acrylate]
3.2.4 Synthesis and characterization of copolymers of 2-(p- 142
dimethylamino-N-methylanilino)ethyl methacrylate with
methyl acrylate
3.2.5 Synthesis and characterization of copolymers of 2-(p- 147
dimethylamino-N-methylanilino)ethyl acrylate with methyl
acrylate
3.2.6 Synthesis and characterization of copolymers of 4-(p- 152
dimethylamino-N-methylanilino)butyl acrylate with methyl
acrylate
3.2.7 Synthesis and characterization of copolymers of 2-(p- 157
dimethylamino-N-methylanilino)ethyl methacrylate with
styrene
3.2.8 Synthesis and characterization of copolymers of 2-(p- 161
dimethylamino-N-methylanilino)ethyl acrylate with styrene
3.2.9 Synthesis and characterization of copolymers of 4-(p- 162
dimethylamino-N-methylanilino)butyl acrylate with styrene
3.3 Experimental section 165
3.3.1 General 165
3.3.2 Gel permeation chromatography 165
3.3.3 Purification of AIBN 166
3.3.4 Purification of methyl acrylate 166
3.3.5 Purification of styrene 166
3.3.6 Attempted anionic polymerization of 2-(p-dimethylamino-N- 167
methylanilino)ethyl methacrylate
3.3.7 Synthesis of poly[2-(p-dimethylamino-N-methylanilino)ethyl 169
methacrylate]
3.3.8 Synthesis of poly[2-(p-dimethylamino-N-methylanilino)ethyl 170
acrylate]
3.3.9 Synthesis of poly[4-(p-dimethylamino-N-methylanilino)butyl 172
acrylate]
3.3.10 Synthesis of copolymers of 2-(p-dimethylamino-N- 173
methylanilino)ethyl methacrylate with methyl acrylate
3.3.11 Copolymers of 2-(p-dimethylamino-N-methylanilino)ethyl 176
acrylate with methyl acrylate
ix
3.3.12 Copolymers of 4-(p-dimethylamlno-N-methylanlllno)butyl 178
acrylate with methyl acrylate
3.3.13 Synthesis of copolymers of 2-(p-dimethylamino-N- 180
methylanilino)ethyl methacrylate with styrene
3.3.14 Copolymers of 2-(p-dimethylamino-N-methylanilino)ethyl 183
acrylate with styrene
3.3.15 Copolymers of 4-(p-dimethylamino-N-methylanilino)butyl 185
acrylate with styrene
Chapter IV Electrochemical investigation of the polymers
4.1 Introduction 188
4.1.1 Cyclic voltammetry 188
4.1.1.1 Cyclic voltammetric responses for freely diffusing species 189
4.1.1.2 Cyclic voltammetric responses for surface immobilized 191
monolayers
4.1.1.3 Polymer films 193
4.1.2 Methods for modifying the surface of an electrode with 195
electroactive polymers
4.2 Results and discussion 196
4.2.1 Electrochemical studies of p-dimethylamino-N,N- 196
dimethylaniline
4.2.2 Cyclic voltammetric studies of the homopolymers in solution 199
4.2.3 Spectroelectrochemical studies with the homopolymers 205
4.2.4 Cyclic voltammetric studies for copolymers with methyl 208
acrylate
4.2.5 Cyclic voltammetric studies of the styrene copolymers 209
4.2.6 Investigation of the mediation by the electroactive polymers 222
4.2.7 Some suggestions for application of these electroactive 226
polymers
4.3 Experimental section 227
X