Synthesis and characterization of functional diblock copolymers [Elektronische Ressource] / vorgelegt von Sachin Borkar

Prof Siesler

Informations

• Publié par: universitat_duisburg-essen
• Publié le: 01 janvier 2003
• Nombre de lectures: 47
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

Synthesis and Characterization of
Functional Diblock Copolymers



Dissertation
zur Erlangung des Doktorgrades
der Naturwissenschaften
im Fachbereich Chemie
der Universität Duisburg-Essen




vorgelegt von
Sachin Borkar
aus Pune (Indien)










November 2003

Statement

The work described in this thesis was carried out in the laboratories of the University of
Duisburg-Essen, Department of Physical Chemistry, Essen, Germany, and The Danish
Polymer Centre, Technical University of Denmark, Kgs. Lyngby, Denmark, between January
2001 and October 2003. Except for the elemental analysis and the optical anisotropy
measurements (Chapter 4.4) this work is entirely that of the author.



































Date of the oral examination: November 11, 2003
Referee: Prof. Dr. H. W. Siesler
Coreferee: Prof. Dr. M. Ulbricht






Dedicated
to my
Parents
Preface

Preface

The thesis entitled “Synthesis and Characterization of Functional Diblock
Copolymers” is submitted to the University of Duisburg-Essen, Germany, for the award of a
PhD degree in Chemistry.
The work reported here was carried out under the guidance of Prof. Dr. H. W. Siesler
(Department of Chemistry, University of Duisburg-Essen, Essen) and Prof. Dr. S. Hvilsted
(The Danish Polymer Centre, Technical University of Denmark, Lyngby, Denmark).
I am sincerely thankful to Professor Heinz Siesler, for his timely help and giving me
an opportunity to work under his guidance. I am also grateful for his great care not only in
academic but also for kind help for social life during my stay in Germany.
I am deeply thankful to Professor Søren Hvilsted for his guidance and immense
cooperation during my stay at the Technical University of Denmark. Also I am very much
thankful for the fruitful discussions and his great help during the process of publications and
thesis writing.
Special thanks are due to Dr. Katja Jankova, for her helpfulness during my stay in the
Danish Polymer Centre. And also to Professor Mathias Ulbricht for providing me the
synthetic facility at the Technical Chemistry Department of the University of Duisburg-Essen.
I am very much thankful to my elder brother Mr. Praveen Borkar, for his inspiration
and support.
The staff at The Danish Polymer Centre, Denmark and Department of Physical
Chemistry and Department of Organic Chemistry at the University of Duisburg-Essen, is
thanked for providing a very friendly and cooperative atmosphere. Special thanks to Dr. P.S.
Ramanujam and Lian Nedelchev for optical anisotropy measurements.
Also, I am gratified to all my friends and colleagues for their moral support during my
academic or non-academic life.
Finally I would like to express my most sincere indebtedness to my parents, other
family members and research colleagues from National Chemical Laboratory, Pune, India, for
their encouragement and support throughout my career. The financial support from the
Ministry of Science and Education of North-Rhein Westfalia, Dusseldorf and the Danish
Polymer Centre, Lyngby, Denmark are gratefully acknowledged.

Sachin Vinayak Borkar

Contents

Contents
Preface
Summary
Chapter 1 Introduction 1
1.1 Liquid Crystals 2
1.1.1 Smectic LC Phase 3
1.1.2 Nematic
1.1.3 Cholesteric LC Phase
1.1.4 Columnar
1.1.5 Effect of Substituent and Spacer Length on the Properties of LC 3
1.2 Liquid Crystalline Polymers (LCPs) 4
1.3 Results of Experimental Work on Azobenzene Containing Polymers 5
1.4 Living Anionic Polymerization 7
1.5 Controlled Radical Polymerization (CRP) 8
1.6 Atom Transfer Radical Polymerization (ATRP) 9
1.6.1 Catalyst System 12
1.6.2 ATRP Monomers 15
1.6.3 Initiators 17
1.6.4 Solvents 20
1.7 Fluoropolymers 21
1.7.1 Historical Perspective 21
1.7.2 Fluorinated Polymer System in Membrane Science and Coatings 22

Chapter 2 Characterization Methods 25
2.1 Size Exclusion Chromatography (SEC) 26
2.2 Differential Scanning Calorimetry (DSC) 26
2.3 Thermogravimetric Analysis (TGA)
1 13 192.4 H, C and F Nuclear Magnetic Resonance (NMR) Spectroscopy 26
2.5 UV-visible Spectroscopy 26
2.6 Fourier Transform Infrared Spectroscopy (FT-IR) 27
2.7 Contact Angle (CA) Measurements 27
2.8 X-Ray Photoelectron Spectroscopy (XPS) 27
2.9 Optical Anisotropy Measurements 28
Contents

Chapter 3 Polymerization of Styrenic LC Monomer by the ATRP Technique 30
3.1 Introduction 31
3.2 Materials and Experimental 32
3.2.1 Materials 32
3.2.2 Experimental
3.2.2.1 Synthesis of 4-(4-hydroxyphenylazo) benzonitrile 32
3.2.2.2 Synthesis of 4-[4-(6-hexyloxy)phenylazo] benzonitrile 33
3.2.2.3 Synthesis of 4-vinylbenzoic acid-6-[4-(4-cyano-phenylazo)
phenoxyl]hexyl ester 34
3.2.2.4 Polymerization of 4-vinylbenzoic acid-6-[4-(4-cyano-
phenylazo)phenoxyl]hexyl ester 34
3.3 Results and Discussion 35
3.3.1 Synthesis of Precursor 35
3.3.2 Synthesis of 4-vinylbenzoic acid 39
3.3.3 Synthesis of 4-vinylbenzoic acid-6-[4-(4-cyano-phenylazo)
phenoxyl] hexylester and its Polymerization 39
3.4 Conclusions 47

Chapter 4 Synthesis and Characterization of Photoaddressable Polymers 48
4.1 Introduction 49
4.2 Experimental 50
4.2.1 Materials 50
4.2.2 Synthesis of 4-(4-hydroxyphenylazo) benzonitrile 50
’4.2.3 Synthesis of 4(ω-bromoalkoxy)-4-cyanoazobenzenes 51
4.2.4 Synthesis of PS-b-PBS Copolymer 55
4.2.5 Hydrolysis of PS-b-PBS 56
4.2.6 Functionalization of PS-b-PHS with 4( ω-bromoalkoxy)-4’-
cyanoazobenzene 57
4.3 Results and Discussion 59
4.3.1 Mesogen Synthesis 59
4.3.2 Synthesis of the PS Backbone Copolymer 63
4.3.3 Functionalization Reactions 68
4.4 Investigation of the Stability of Optical Anisotropy 73
4.4.1 Stability in the Presence of Light 75
Contents

4.4.2 Thermal Stability of Anisotropy 76
4.4.3 Response of Anisotropy 78
4.5 Conclusions 80

Chapter 5 Novel Fluorinated Polymer Materials Based on 81
2,3,5,6-tetrafluoro-4-methoxystyrene
5.1 Introduction 82
5.2 Experimental 83
5.2.1 Monomers
5.2.2 Side-chain Precursors 83
5.2.3 Polymerizations
5.2.4 Azobenzene Functionalization 84
5.3 Results and Discussion 84
5.3.1 Monomer Preparation and Polymerizations 84
5.3.2 Block Copolymerization of PTFMS with St or FS 89
5.3.3 Thermal Properties of PTFMS and its Block Copolymers 91
5.3.4 Solubility Parameters of PTFMS Homopolymers 92
5.3.5 Surface Properties of PTFMS and its block Copolymers 93
5.3.6 Demethylation Reaction 93
5.3.7 Functionalization Reaction with Azobenzene Precursors 94
5.4 Conclusions 97

Chapter 6 Synthesis of Novel Fluorinated Styrene Monomers for ATRP:
Homopolymerization as well as Block Copolymerization with
Styrene and Pentafluorostyrene 98
6.1 Introduction 99
6.2 Experimental
6.2.1 Materials 99
6.2.2 Synthesis of TF(F )S and TF(F)S 99 5 15
6.2.3 Polymerization Procedure 100
Contents

6.3 Results and Discussion 101
6.3.1 Monomer Synthesis 101
6.3.2 Homopolymerization as well as Block Copolymerization of 104
TF(F )S and TF(F )S 5 15
6.3.3 Thermal Properties 107
6.3.4 Surface 109
6.4 Conclusions 112

Chapter 7 Engineering End-functional Low Energy Surface PS Through
Molecular Design: Synthesis of Fluorinated and non-Fluorinated
Initiators for ATRP 113
7.1 Introduction 114
7.2 Experimental 115
7.2.1 Materials 115
7.2.2 Synthesis of the F-15Br Initiator 115
7.2.3 ATRP of St and FS 117
7.3 Results and Discussion 117
7.3.1 Synthesis of Fluorinated and non-Fluorinated Initiators 117
7.3.2 Polymerization of St or FS 119
7.3.3 Thermal Properties 122
7.3.4 Contact Angle Measurements 124
7.3.5 XPS Analysis 127
7.4 Conclusions 129

Chapter 8 References 130

Summary i

Summary

In search of materials for high-density optical data storage by irradiation with
polarized laser light liquid crystalline polymers containing azobenzene functionalities in the
side chains have attracted great attention. These azobenzene groups generate different
photoisomerization phenomena which can be exploited for optical data storage by using