Liquid Crystalline Polymers

✍ Scribed by Xin-Jiu Wang, Qi-Feng Zhou

• Publisher: World Scientific Pub Co Inc
• Year: 2004
• Tongue: English
• Leaves: 389
• Category: Library

✦ Synopsis

This textbook consists of six chapters. The first chapter highlights the concept of liquid crystals, including chemical structure, phase classification, defect and texture, and continuum theory. It has been carefully written to meet the needs of readers who do not specialize in liquid crystals. The second chapter is related to the theoretical description of liquid crystalline polymers, networks, and gels, which deals with subjects such as the formation of liquid crystallinity in the polymer system, the phase transition and phase diagram, the molecular weight effect, chain conformation, physics properties and so on. In Chapter 3, the molecular engineering of liquid crystalline polymers is introduced. The molecular composition and the molecular weight play essential roles in the molecular design, which are reviewed in detail. In addition, some unusual liquid crystalline polymers are discussed. Chapter 4 is devoted to the phase identification of liquid crystalline polymers. The techniques involved cover polarizing microscopy, thermal analysis, X-ray diffraction, and other areas. Chapters 5 and 6 summarize the properties and applications of liquid crystalline polymers: Chapter 5 deals mainly with mechanical performance in fiber and composites; Chapter 6 presents the elasticity, viscosity and rheology of liquid crystalline polymers, as well as other important properties.

✦ Table of Contents

Contents......Page 6
Preface......Page 12
1.1 Liquid Crystal States......Page 16
1.2 Appearance and Light Scattering of Liquid Crystals......Page 19
2. Terminal group:......Page 21
1.3.2 Discotic liquid crystals......Page 22
1.3.3 Amphiphilic liquid crystals......Page 24
1.4 Polymorphism of Liquid Crystals......Page 26
1.4.1 No translational order — Nematics......Page 27
1.4.2 One-dimensional translational order — Smectic A and C phases......Page 28
1.4.3 Two-dimensional translational order within layers with weak correlation along the third dimension — Hexatic phases......Page 30
1.4.4 Three-dimensional translational order but correlation is weaker than that in crystals......Page 32
1.4.5.2. Chiral smectic liquid crystals......Page 34
1.4.6.1. D phase......Page 36
1.4.6.3. Blue phase......Page 37
1.4.7 Discotic liquid crystals......Page 38
1.4.8.1. Amphiphilic liquid crystals......Page 40
1.4.9 Induced liquid crystals......Page 41
1.5.1 Order parameter......Page 42
1.5.2 Distortions of liquid crystals......Page 44
1.5.3 Frederiks transitions......Page 46
1.5.4 The twisted – and supertwisted – nematic liquid crystals......Page 49
1.6 Defects in Liquid Crystals......Page 50
1.6.1 The Volterra process......Page 51
1.6.2 Strength of disclination in nematics......Page 53
1.6.3 Point disclinations......Page 57
1.6.4 Defects in smectic A phase......Page 59
The edge dislocation......Page 60
The focal-conic texture......Page 61
The χ-, λ- and τ -disclinations......Page 62
1.6.8 Textures......Page 64
1.6.9 Homotopy classification of defects in liquid crystals......Page 65
2 Theories of Liquid Crystalline Polymers......Page 68
2.1 Onsager Theory for Rigid – Rod Liquid Crystalline Polymers......Page 69
2.1.1 The partition function......Page 70
2.1.2 The excluded volume......Page 76
2.1.3 The equilibrium of liquid crystals......Page 77
2.2.1. Partition function of a rigid rod solution......Page 80
2.2.2 Formation of the liquid crystal phase......Page 84
2.2.3 Two phase equilibrium......Page 86
2.2.4 Effect of “soft” interaction between molecules......Page 89
2.2.5 Semi-rigid chains......Page 93
2.2.6 Discussion of the Flory theory......Page 94
2.3 Comparison of the Onsager and Flory Theories......Page 96
2.4.1 Maier-Saupe mean field theory for small molecular mass liquid crystals......Page 101
2.4.2.1. Liquid crystallinity......Page 103
2.4.2.2. Polymer conformations......Page 104
2.4.3 Elastically-jointed-rod chains......Page 105
2.4.4 Discrete and continuum chain models......Page 110
2.5.1 Path integral description for polymers......Page 111
2.5.2 Anisotropic conformation......Page 114
2.5.4 Dependence of N–I transition on polymer chain length......Page 116
2.5.5 Latent entropy at transition......Page 117
2.6.1 Molecularly non-homogeneous liquid crystalline polymers......Page 118
2.6.3 Hinge effect......Page 123
2.7.1 Model......Page 125
2.7.2 Phase classification of side chain nematic polymers......Page 126
2.7.3 Order parameter and phase transitions......Page 127
2.7.4 Conformations......Page 130
2.8 Liquid Crystalline Networks......Page 131
2.8.1 Conventional networks......Page 132
2.8.2 Model of liquid crystal networks......Page 134
2.8.3 Relation of stress and strain......Page 136
2.9.1 Nematogetic network swollen by isotropic solvent......Page 139
2.9.2 Nematogetic network swollen by nematic solvent......Page 141
2.9.3 The shift of phase equilibria under the presence of force......Page 146
3.1 Introduction......Page 148
3.2 Low Mass Liquid Crystalline Compounds and Mesogenic Units......Page 153
3.2.2 Incorporation of “side-steps”......Page 154
3.2.3 Incorporation of kinked elements......Page 157
3.2.5 Terminal or end-on substitution......Page 158
3.2.6 Lateral or side-on substitution......Page 160
3.3 Molecular Weight and Molecular Weight Distribution......Page 162
3.4 Main Chain Liquid Crystalline Polymers......Page 170
3.5.1 Synthesis......Page 181
3.5.2 Structure and properties......Page 186
3.6 Liquid Crystalline Polymers of the Side-group Type with Side-on Attachment and “Mesogen-jacketed Liquid Crystal Polymers”......Page 192
3.7 Liquid Crystalline Polymers without Mesogenic Units......Page 203
4 Characterization of Liquid Crystalline Polymers......Page 210
4.1 Polarizing Optical Microscopy (POM)......Page 212
4.1.1 Optical basics for POM......Page 213
4.1.2 Orthoscopic observation......Page 216
4.1.3 Conoscopic observation......Page 221
4.1.4 Textures of polymeric liquid crystals......Page 224
4.2 Differential Thermal Analysis (DTA) and Dierential Scanning Calorimetry (DSC)......Page 236
4.3 X-Ray Diffraction......Page 243
4.4.1 Miscibility testing......Page 252
4.4.2 Infrared dichroism......Page 253
4.4.3 NMR study......Page 255
4.4.4 Small-angle neutron scattering......Page 256
5.1 Introduction......Page 260
5.2 Liquid Crystalline Aromatic Polyamides......Page 261
5.3 Liquid Crystalline Aromatic Heterocyclic Polymers......Page 269
5.4 Thermotropic Liquid Crystalline Polymers......Page 274
5.4.1 Type-1 copolyesters......Page 276
5.4.2 Type-2 copolyesters......Page 279
5.4.3 Type-3 copolyesters......Page 283
5.5 Composites Reinforced by Liquid Crystalline Polymers......Page 286
6.1 Elastic Properties of Liquid Crystalline Polymers......Page 300
6.2 Viscosity and Rheology of Liquid Crystalline Polymers......Page 315
Selective reflection......Page 330
Optical activity......Page 331
Electro-optic effects......Page 332
6.3.2 Lyotropic cholesteric liquid crystalline polymers......Page 333
Pitch as a function of concentration......Page 334
Pitch as a function of temperature......Page 335
Pitch on side chains of poly-peptides......Page 337
Biological cholesteric liquid crystalline polymers......Page 339
6.3.3.1. Main chain cholesteric liquid crystalline polymers......Page 341
6.3.3.2. Side chain cholesteric liquid crystalline polymers......Page 342
6.4 Non-Linear Optical Liquid Crystalline Polymers......Page 344
6.5 Ferroelectric Liquid Crystalline Polymers......Page 356
6.6.1 Nematic liquid crystalline polymers......Page 365
6.6.2 Smectic liquid crystalline polymers......Page 367
6.6.3 Cholesteric liquid crystalline polymers......Page 368
6.6.4 Photo-isomeric change......Page 369
References......Page 370
Index......Page 386