Conjugated Polymers: The Novel Science and Technology of Highly Conducting and Nonlinear Optically Active Materials

624 Pages·1991·21.63 MB·English

by  C. B. Gorman

CONJUGATED POLYMERS
Conjugated Polymers
The Novel Science and Technology of
Highly Conducting and Nonlinear
Optically Active Materials
Edited by
J.L. Bredas
Laboratory for Chemistry of Novel Materials,
University of Mons-Hainaut, Mons, Belgium
and
R. Silbey
Department ofChemistry,
Massachusetts Institute ofTechnology, Cambridge, U.S.A.
SPRINGER SCIENCE+BUSINESS MEDIA, B.V.
Library of Congress Cataloging-in-Publication Data
Conjugated polymers : the novel science and technology of highly
conducting and nonlinear optic~lly acttve materials I edited by J.L.
Bredas and R. Stlbey.
p. cm.
Includes btbliographtcal references and index.
ISBN 978-94-010-5536-9 ISBN 978-94-011-3476-7 (eBook)
DOI 10.1007/978-94-011-3476-7
1. Polymers--Electric properties--Congresses. 1. Bredas, J. L.
(Jean Luc), 1954- II. Silbey, Robert J,
OD381,9.E38C665 1991
620_"9297--dc20 91-27648
ISBN 978-94-010-5536-9
Printed on acid-free paper
All Rights Reserved
© 1991 Springer Science+Business Media Dordrecht
Originally published by Kluwer Academic Publishers in 1991
Softcover reprint ofthe hardcover Ist edition 1991
No part of the material protected by this copyright notice may be reproduced or
utilized in any form or by any means, electronic or mechanical,
including photocopying, recording or by any information storage and
retrieval systern, without written permission from the copyright owner.
TABLE OF COMTEHTS
PREFACE
CONJUGATED POLYMERS: THE IMTERPLAY BETWEEN SYNTHESIS, 1
STRUCTURE, AND PROPERTIES
C.B. GORMAN and R.H. GRUBBS
1. Introduction 2
2. Structural Features of Conjuqated. Polyaers 3
3. Polymer Synthesis: Basic Methods 4
3.1 Step-Growth Polymerization 5
3.2 Chain-Growth Polymerization 6
3.3 Rinq-Openinq Polymerization 8
4. Direct Synthetic Methods 8
4.1 Electrochemical Synthesis 9
4.2 Synthesis by Step-Growth Polymerization 11
4.2.1 Polyaniline (PAN) 11
4.2.2 Poly(Phenylene Sulfide) 12
4.2.3 Polyt hiophene and its Derivatives 13
4.2.4 Other 5-membered Heterocyclic 16
Derivatives
4.2.5 Polyparaphenylene (PPP) 17
4.2.6 Polysilanes 18
4.2.7 Polymers of Phthalocyanines 19
4.2.8 Other Conjugated Metal Coordination 20
Polymers
4.2.9 Ladder Polymers 21
4.3 The Unusual Topochemical Polymerization to 23
form Polydiacetylenes
4.4 Chain-Growth Polymerizations 24
4.4.1 Polyacetylene via Ziegler-Natta 24
Polymerization
4.4.2 Ring-Opening Metathesis Polymerization 26
Routes to Polyacetylenes
5. Polymers fro. precursors 27
5.1 Polyparaphenylene (PPP) 27
5.2 Poly(Phenylene Vinylene) (PPV) and Other 28
Vinylene Polymers
5.3 Precursors to Polyacetylene 29
6. Extentions of these Methods in the Synthesis of 31
·saall-Bandqap· Pplymers
7. Conjuqated. Polymer Matrices 33
8. Conclusions and Caveats 35
Acknowled.qements 36
References 36
vi TABLE OF CONTENTS
PROPERTIES OF HIGHLY CONDUCTIHG POLYACETYLEHE 49
Th. SCHIMMEL, D. GLASER, M. SCHWOERER AND
H. NAARMANN
1. Introduction 50
2. SBIlpie Synthesis, lIorphology and Properties 52
2.1 Standard Routes of Synthesis 52
2.2 Naarmann-Type Polyacetylene 53
3. Conductivity: Experiaental 53
3.1 The Standard Four-Probe and Montgomery 53
Techniques
3.2 Test of Sample Homogeneity 55
3.3 Conductivity Measurement 56
3.4 Sample Preparation 57
4. COnductivity lIeasureaents: Experi:aental Results 58
4.1 General Remark 58
4.2 Temperature Dependence of a and a~ 59
4.3 Conductivity at Very Low Temperatures 60
(14mK - 4.2 K)
4.4 Anisotropy and Stretching Ration 61
4.5 Aging Effects in aCT) 62
4.6 Anisotropy and Aging 64
4.7 Dependence of aCT) on the Dopant Concentration 66
4.8 Doping with FeC1 68
3
4.9 Pressure Dependence 68
5. Discussion of aCT) 69
5.1 Experimental Prerequisites for a Model of 69
Charge Transport for T > 400 mK
5.2 The Failure of Conventional Models 70
5.3 Description with the Sheng Formula 72
5.4 Limits of the Applicability of Sheng's Model 76
5.4.1 Low Temperature Limit 76
5.4.2 Image Charge Correction Parameter A 77
5.4.3 Possible Temperature Dependence of a. 79
5.4.4 Paasch's Approach - 79
5.5 Evaluation within a Phenomenological Model 79
5.6 Influence of the Barriers on a (300 K) 81
5.7'The Influence of Phonon Scattering on the 82
Conductivity
5.8 Low Temperature Behaviour and Aging 84
5.8.1 Describing afT) with Sheng's Formula 84
5.8.2 Influence of Finite Chain Lenghts 85
5.9 Conclusions 87
6. lIorphology and Charge Transport 88
6.1 SEM on Freshly-Prepared Samples 88
6.1.1 Sample Preparation for SEH 88
6.1.2 Results 88
6.2 Local Density and Bulk Density 93
6.3 Geometrical and Electrical Anisotropy 94
6.4 Influence of Oxygen Aging and Iodine Doping 96
TABLEOFCONTENTS vii
6.4.1 oxidation by oxygen ("Aging") 96
6 • 4 • 2 oxidation by Iodine ("Doping") 97
6.4.3 Charging Effects 98
6.5 TEM on Individual polyacetylene Fibrils 100
6.5.1 Experimental 100
6.5.2 Results 102
7. Conductivity Barriers and Morphology: 105
a Comparison
8. Summary and Outlook 106
Acknowledgements 108
Literature 109
ELECTRONIC PROPERTIES OF HEAVILY DOPED TRANS- 113
POLYACETYLENE
S. STAFSTROM
1. Introduction 113
2. Models for the Metallic state of Heavily Doped 114
Trans-(CH)"
3. Methodology 118
3.1 Hamiltonian 118
3.2 Self-Consistent Calculation Scheme 122
3.3 Description of the Optimized Systems 123
3.4 Polaron Lattice 123
3.5 Density of States 124
4. Results and Discussion 124
4.1 Optimized Geometry using the Conwell-Mizes- 125
Jeyadev Potential
4.2 The Effect of Intra-Chain Electron-Electron 128
Interactions
4.3 Disordered System 130
4.4 Polaron Lattice 132
4.5 Evolution of the Energy Gap as a Function of 133
Doping Level
4.6 Density of States 134
5. Summary and Conclusion 136
Acknowledgements 137
References 138
SOLUTION PROCESSING OF CONDUCTING POLYMERS: 141
OPPORTUNITIES FOR SCIENCE AND TECHNOLOGY
ALAN J. HEEGER AND PAUL SMITH
I. Introduction 141
A. Conducting Polymers: Materials with a Unique 141
Combination of Electrical and Mechanical
Properties
B. Conducting Polymers: Approaches to Processing 142
viii TABLE OF CONTENTS
C. Blends of Conducting polymers with saturated 146
Polymers
II. Conducting Polyaers in SOlution 146
A. Electronic structure (and conformation) of 146
the Neutral Polymers in Solution
B. Electronic Structure (and Conformation) of 149
the Doped Polymers in Solution
III. Electrical and Mechanical Properties of 172
oriented Poly(3-alkylthiophenes) Processed
from SOlution
A. Fiber Spinning and Drawing 173
B. Characterization of the Drawn P30T Fibers 174
C. Effect of Side-Chain Length 178
IV. Gels and Blends of the P3AT's Processed from 179
solution
A. Conducting polymer Blends of Soluble 179
Polyt hiophene Derivatives in Polystyrene
B. Conducting Polymer Gels: A Self Assembling 181
Conducting Network with Remarkably Low
Percolation Threshold
V. Electrical and Mechanical Properties of 184
Polyaniline and Blends of Polyaniline with PPTA
Processed from Solution in Sulfuric Acid
A. Preparation of the PANI/PPTA Blends and PANI/ 185
PPTA Fiber Spinning
B. Properties of the PANI/PPTA Fibers 185
VI. Electrical and Mechanical Properties of Pl'V and 188
PDMPV
A. Preparation of Precursor Polymers, Fiber 188
Spinning, Drawing and Conversion of PTV and
PDMPV
B. Electrical and Mechanical Properties of PTV 192
C. Electrical and Mechanical Properties of PDMPV 194
VII. Mechanical and Electrical Properties of Poly- 196
acetylene Fil.s oriented by Tensile Drawing
A. Polymerization and Tensile Drawing 197
B. X-Ray Diffraction 197
C. Mechanical Properties 199
D. Electrical Conductivity 201
VIII. Correlation between Electrical Conductivity 203
and Mechanical Properties
IX. Conclusion 204
AcknovledgeJlellt 206
References 206
THE POLYANILINES: MODEL SYSTEMS FOR DIVERSE 211
ELECTRONIC PHENOMENA
ARTHUR J. EPSTEIN
1. Introduction 211
2. Leucoeaeraldine Base (LEB) 213
TABLE OF CONTENTS ix
3. Ring Rotation Polarons and Solitons 216
4. Eaeraldine Base 220
5. Pernigraniline Base 220
6. -Metallic- Polyaniline 222
7. Effects of Derivitization 223
8. Sumaary 224
9. Acknowledgement 224
10. References 224
STRUCTURAL CHARACTERIZATION OF CONJUGATED POLYMER 229
SOLUTIONS IN TIlE URDOPED AND DOPED STATE
JEAN-PIERRE AIME
1. Introduction 229
2. Polyaer SOlutions 231
2.1 Models for Single Chains 231
2.1.1 Ideal Chain 231
2.1.2 Real Chain in Good Solvent 232
2.1.3 Chain with Local stiffness: Kratky- 233
Porod-Model
2.2 Notion of Theta and Good Solvent for Linear 235
Saturated Polymer
2.2.1 Mean Field Picture 235
2.2.2 osmotic Pressure 237
References 239
3. Structural Studies with S.all Angle SCattering 240
3.1 Basic Principles 240
3.2 Scattering at Small Angle 241
3.3 Small Angle Scattering from Polymers in 243
Solution
3.3.1 Incompressibility and Contrast Factor 243
3.3.2 Form Factor 245
3.4 Models for Polymer Chains 246
3.4.1 Ideal Chains 246
3.4.2 Chain in Good Solvent, Flexible Chain 247
with Interactions
3.4.3 Scattering Function of Chain with 249
Persistence Length
3.5 Scattering Measurements in Real Polymer/ 253
Solvent Systems
3.5.1 Polydispersity Effect 253
3.5.2 Models for Chain Cross section 254
References 257
4. SOluble COnjugated Poly.ers 259
4.1 Conjugated Polymers with SUbstituents 259
4.1.1 Substituted polyacetylenes 260
4.1.2 Poly-n-alkylthiophenes 261
4.1.3 Polydiacetylenes 262
4.2 Diblock Copolymers and Graft Copolymers 263
x TABLE OF CONTENTS
4.2.1 Graft Copolymer 264
4.2.2 Sequence of Block-Copolymer 265
References 266
5. Polydiacetylenes 268
5.1 Introduction 268
5.2 statistical Conformation in Good Solvent: 269
Yellow Solution
5.3 Origin of the Blue and Red Shifts in Good 274
Solvent: Chain Conformation and Solvato-
chromism
5.4 Color Transition: Aggregation versus Single 276
Chain Process
References 281
6. study of Dopable Polyaers: PAIII and Poly-n- 283
Alkylthiophenes
6.1 Doped Polymers in the Solid Phase 283
6.2 Doped Polymers in Solution: Poly-n- 286
alkylthiophene
6.2.1 structure of Poly-3-butylthiophene in 286
the Neutral state
6.2.2 Charged poly-n-alkylthiophene in 288
Solution
References 294
7. Does Conjuqated Polyaer Behave Like saturated 296
One
7.1 Conformation of Soluble Conjugated Polymers: 296
Origin of the Local Rigidity
7.1.1 Thermal behavior of the PDA PTS12 in 297
Good Solvent
7.1.2 Experimental Evidence of the Influence 302
of the Side-Group Extension
7.2 Aggregation Process for Conjugated Polymers 306
7.2.1 Observed Conformations for Polymers in 306
Good Solvent
7.2.2 Model for Conjugated Polymers 308
Acknowledqe.aent 312
References 312
PROCESSABLE COIfDUCTIIIG POLY (3-ALKYLTliIOPEllBS) 315
G. GUSTAFSSON, O. INGANAS, W.R. SALANECK, J. LAAKSO,
M. LOPONEN, T. TAKA, J.-E. OSTERHOLM, H. STUBB,
T. HJERTBERG
1. Introduction 315
2. Synthesis 317
2.1 Monomer Synthesis 317
2.2 Polymerization 318
3. Characterization 320
3.1 Infrared Spectroscopy 320
TABLE OF CONTENTS xi
3.2 NMR 321
3.3 Elemental Analysis 322
3.4 Thermal Analysis 323
3.5 Molecular Weight 324
3.6 Optical Spectra 324
3.7 X-Ray Diffraction 325
4. Processability-polymer Blends 327
4.1 Processability 327
4.2 Polymer Blends 327
5. Electronic structure and Conformational 329
Excitations
5.1 Electronic Structure 329
5.2 Conformational Excitations: Thermochromism 332
and Solvatochromism
6. Doping and stability 337
6.1 Methods of Doping 337
6.2 Conductivity 338
6.3 Dedoping 339
7. Transport Properties 343
7.1 Field Effect Transistors for Transport 343
Property Studies
7.2 Poly(3-Alkylthiophene) Blends 345
8. Stretch Orientation of Poly(3-Alkylthiophenes) 347
9. Applications . 350
9.1 Applications through processability 350
9.2 Electronic Devices: Transistors and Diodes 351
9.3 Nonlinear optical Properties 352
10. Conclusions 353
Acknowledgeaents 353
References 354
CONTROLLED MOLECULAR ASSEMBLIES OF ELECTRICALLY 363
CONDUCTIVE POLYMERS
M.F. RUBNER AND T.A. SKOTHEIM
1. Introduction 363
2. Fabrication of Monolayer and Multilayer Thin 364
Films of Electrically Conductive Polymers
3. Molecular and Superwolecular Organizations 376
of LB Films Containing Conducting Polymers
3.1 X-Ray Diffraction Studies 377
3.2 Orientation Studies by FTIR 381
3.2.1 orientation studies of LB Films 381
Fabricated with the Poly(3-
alkylthiophenes)
3.2.2 orientation studies of LB Films 384
Fabricated with Surface Active
pyrroles and Polypyrrole
3.3 Orientation Studies by NEXAFS 387