Liquid Crystalline and Mesomorphic Polymers

Transcription

1 Valery P. Shibaev Editors Lui Lam Liquid Crystalline and Mesomorphic Polymers With 199 Illustrations Springer-Verlag New York Berlin Heidelberg London Paris Tokyo Hong Kong Barcelona Budapest

2 Contents Preface Contributors v xv 1 Molecular Theory of Cholesteric Polymers 1 M.A. Osipov 1.1 Introduction Elementary Models for Chiral Molecules Chiral Anisotropic Interaction Between Macromolecules in the Solvent Model Potentials Solvent Effect on the Chiral Intermolecular Interaction Statistical Theory of Cholesteric Ordering General Theory Temperature and Solvent Effect on the Cholesteric Pitch in Polypeptide Solutions Cholesteric Ordering in Biopolymer Solutions Influence of Solvent Chirality on the Cholesteric Ordering Influence of Molecular Flexibility on the Cholesteric Ordering in Polymer Solutions 21 References 23 2 Structure of Thermotropic Main-Chain Polymers 26 A.H. Windle 2.1 Introduction Scope Main-Chain Mesogenic Systems Molecular Architecture 30

3 x Contents Theoretical Background Architecture of Isolated Polymer Molecules Persistence Length as a Critical Parameter Kuhn Chains Change in Chain Parameters in the Nematic Phase Microstructural Considerations Involving Nematic Polymers Levels of Order in Mesophases of Main-Chain Liquid Polymers Classification for Polymers Aspects of Chain Structure Basis for Classification Mesophases Formed by Successive Shear Disorder of the Crystal Mesophases Formed by Paracrystalline Disorder in One Lateral Dimension Mesophases Resulting from Paracrystalline Disorder in the Two (Lateral) Dimensions, and Translational Melting in Two Dimensions Audit of Possible Combinations Occurrence of Mesophase Structures Disruption of Order along the Chain Axis 73 References 74 Molecular Architecture and Structure of Thermotropic Liquid Crystal Polymers with Mesogenic Side Groups 77 V.P. Shibaev, Ya.S. Freidzon, and S.G. Kostromin 3.1 Introduction Molecular Architecture of Liquid Crystal Polymers Specific Features of Comb-Shaped Polymers Associated with Their Macromolecular Nature Mesophase Types of Comb-Shaped Liquid Crystal Polymers. Problems of Classification Effect of Mesophase Type on the Structure of Polymers Oriented by Uniaxial Drawing Nematic Polymers Smectic Polymers Placement of the Main-Chain in Smectic and Nematic Phases of Comb-Shaped Liquid Crystal Polymers Structure of Cholesteric Polymers Structure of Cholesterol-Containing Homopolymers Structure of Cholesterol-Containing Copolymers 113 References 115

4 Contents xi 4 Phase Behavior of High- and Low-Molar-Mass Liquid Crystal Mixtures 121 F. Hardouin, G. Sigaud, and M.F. Achard 4.1 Introduction Binary Mixtures of Low-Molar-Mass Mesogens Mixtures of a Liquid Crystalline Polymer with a Low-Molar-Mass Liquid Crystal Miscibility Properties Other Nonideal Behaviors Conclusions 142 References Polymer-Dispersed Liquid Crystal Films 149 G.P. Montgomery, Jr., G. W. Smith, and N.A. Vaz 5.1 Introduction Film Structure and Operation Film Formation: General Aspects Emulsification NCAP Films Phase Separation Polymer-Dispersed Liquid Crystal Films Polymer-Dispersed Liquid Crystal Formation: Polymer-Induced Phase Separation Systems Formation Model Experimental Studies of Polymer-Dispersed Liquid Crystal Formation Concluding Remarks Regarding Polymer- Dispersed Liquid Crystal Formation Materials Selection Refractive Indices Solubility of Liquid Crystal in Matrix Operating Temperature Range Environmental Stability Film Fabrication and Morphology Ultraviolet-Curing Conditions Droplet Size Distribution Color Electrooptic Properties Refractive Indices and Film Transmittance Transmittance versus Voltage Response Times Spectral Transmittance Characteristics Light Scattering Theoretical Treatments Angle-Dependent Light Scattering Measurements 181

5 xii Contents Transmittance Measurements Droplet Size Effects Concluding Remarks Regarding Light Scattering Final Comments 187 References Nuclear Magnetic Resonance Spectroscopy of Thermotropic Liquid Crystalline Polymers 193 L. Stroganov 6.1 Introduction Thermotropic Liquid Crystalline Polymers with Mesogenic Groups in the Main Chain J H and 2 H Nuclear Magnetic Resonance in Fast Motion Limit Multipulse Dynamic Nuclear Magnetic Resonance Molecular Dynamics Orientational Ordering Biphase Region Macroscopic Ordering Liquid Crystalline Polymers with Mesogenic Groups in the Side Chains Molecular Dynamics and Ordering in the Glassy State Ordering and Dynamics in Liquid Crystalline Phases above the Glass Transition Temperature Biphase Region Macroscopic Ordering 223 References Mesophase of Graphitizable Carbons 231 H. Marsh and M.A. Diez 7.1 Introduction Discotic Nematic Liquid Crystals Formation of the Mesophase Structure in the Mesophase Growth and Coalescence Formation of Anisotropic Carbons Factors Influencing the Formation of Anisotropic Carbons Chemical Factors Physical Factors Graphitization Industrial Relevance of Mesophase: Discotic, Aromatic, and Nematic Liquid Crystals Delayed Coking Metallurgical Coke 253

6 Contents хш Carbon Fibers Graphite Production Carbon Blacks 254 References Mesophase State of Polyorganophosphazenes 258 V.G. Kulichikhin, E.M. Antipov, E.K. Borisenkova, and D.R. Tur 8.1 Introduction Thermodynamics and Structure of Polyorganophosphazenes Relaxation Transitions of Poly-bis-Trifluoroethoxyphosphazenes Properties of Diluted Solutions of Poly-feis-Fluoroalkoxyphosphazenes Rheological Properties of Concentrated Poly-ftis- Trifluoroethoxyphosphazene Solutions Rheological Properties of Poly-bis-Fluoroalkoxyphosphazenes in the Mesophase State Polymer Blends on a Base of Poly-bi's-Trifluoroethoxyphosphazene Conclusions 293 References Chiral Nematic Mesophases of Lyotropic and Thermotropic Cellulose Derivatives 298 D.G. Gray and B.R. Harkness 9.1 Mesophase Formation Mesophases of Cellulose Derivatives Chiral Nematic Properties Theories of the Chiral Nematic State Chiral Nematic Properties of Cellulose Derivatives Reversal of Handedness of Chiral Nematic Cellulosics Circular Dichroism and Induced Circular Dichroism Chiroptical Properties of Specifically Substituted Cellulose Derivatives Concluding Remarks 318 References Bowlics 324 L. Lam 10.1 Introduction The First Paper Bowlic Monomers The Molecules 331

7 xiv Contents Mesophases and Phase Transitions Physical Properties Bowlic Nematics in Electric Fields Bowlic Langmuir Films Bowlic Polymers The Discrete Model for Dilute Solutions The Worm-Like Model for Bowlic Nematic Polymers Ultrahigh T c Bowlic Superconductors Conclusions 350 References 351 Index 354