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The subject of liquid crystals and their use in electronic displays and in non-linear optical systems has become of tremendous importance during the last decade; and the incorporation of liquid crystal units into polymeric materials has led to a group of new materials with diverse properties. Some of these properties have been utilized in new products and some have yet to be used. Much published work has appeared that deals with specific materials or particular applications, and it was felt that a book was needed to examine and explain the underlying principles governing the diverse properties of these liquid crystal polymers, LCPs. The current work describes the diverse nature of LCPs, their synthesis, characterization, properties and finally their applications. It describes the manner in which liquid crystallinity or mesomorphism occurs in small molecules, monomer liquid crystals and polymer liquid crystals. Chapter 1 gives a classification of the various ways in which the meso gens may be connected to the polymer chains. Currently, the bulk of LCP material is based on main chain or longitudinal LCPs for use in engineering applications. The side chain or comb polymers are intended for use in electronics and opto-electronic systems and as surfactants. Many other variants and possibilities exist but their properties have not yet been fully studied or used. In this respect it is hoped that the current work will indicate future possibilities as well as discussing current opinion. v Preface vi Chapters 2 and 3 describe methods of characterizing the mesophases.
Table des matières
1. An Introduction to Liquid Crystallinity.- 1.1 Introduction.- 1.2 A brief history of MLCs and PLCs.- 1.3 Mesophases and their types.- 1.4 Heterogeneous composites, molecular composites and PLCs.- 1.5 The nature of liquid crystallinity.- 1.6 Phases of liquid crystals.- 1.7 Classification of PLCs.- 1.8 Molecular structures, properties and packing.- 1.9 From structures to applications.- References.- 2. Characterization of Mesophases.- 2.1 Introduction.- 2.2 Typical molecular structures.- 2.3 Mesophases of rod-like molecules.- 2.4 Textures and polymorphism of LC polymers.- 2.5 Miscibility tests.- 2.6 X-ray diffraction patterns.- 2.7 Conformation of LCPs as revealed by small-angle scattering methods.- References.- 3. NMR Studies of Thermotropic Polymers.- 3.1 Introduction.- 3.2 NMR investigation of orientational conformational phenomena in mesomorphic polymers.- 3.3 NMR investigation of local dynamics in mesomorphic polymers.- 3.4 NMR investigation of slow motions in mesomorphic polymers.- 3.5 Conclusions.- References.- 4. Dielectric Relaxation in Macromolecular Liquid Crystals.- 4.1 Introduction.- 4.2 Principles of dielectric relaxation spectroscopy.- 4.3 Dielectric spectroscopy of liquid crystals.- 4.4 Dielectric relaxation in polymers.- 4.5 Dielectric spectroscopy of liquid crystal polymers.- References.- 5. Lyotropic Side Chain Polymer Liquid Crystals.- 5.1 Introduction.- 5.2 Physical properties of surfactants.- 5.3 Synthesis of lyotropic side chain polymer liquid crystals.- 5.4 Phase behaviour of lyotropic side chain polymer liquid crystals.- 5.5 Polymerization in oriented monolayers and vesicles.- References.- 6. Lyotropic main chain liquid crystal polymers.- 6.1 Introduction and synthetic aspects.- 6.2 Order in lyotropic polymer solutions.- 6.3 Morphology of fibersand films.- 6.4 Mechanical and thermal properties.- References.- 7. Thermotropic Side Chain Liquid Crystal Polymers.- 7.1 Introduction.- 7.2 General structural features.- 7.3 Structure-property correlations.- 7.4 Copolymers.- 7.5 Synthesis of comb and parallel systems.- 7.6 Applications and applicable materials.- References.- 8. Thermotropic Main Chain Liquid Crystal Polymers.- 8.1 Introduction.- 8.2 Design of thermotropic main chain LCPs.- 8.3 Synthesis of thermotropic main chain LCPs.- 8.4 Characterization and morphology of thermotropic main chain LCPs.- 8.5 Properties of thermotropic main chain LCPs.- 8.6 Applications.- 8.7 Conclusions.- References.- 9. Applications of LCP Materials.- 9.1 Introduction.- 9.2 Injection-moulded products.- 9.3 Extruded LCP rods and profiles.- 9.4 Oriented sheets and films.- 9.5 Thermoforming and blow moulding.- 9.6 Matrix materials for composites.- 9.7 Fibers.- 9.8 Coatings.- References.
