Thermotropic Liquid Crystals: Recent Advances

ISBN-13: 9781402053276 / Angielski / Twarda / 2007 / 340 str.

Ayyalusammy Ramamoorthy

Opis

This book covers developments in the field of thermotropic liquid crystals and their functional importance. It also presents advances related to different sub-areas pertinent to this interdisciplinary area of research. This text brings together research from synthetic scientists and spectroscopists and attempts to bridge the gaps between these areas. New physical techniques that are powerful in characterizing these materials are discussed.

Spis treści

Chapter 1: Mesophase Behaviour at the Borderline between Calamitic and ‘Banana-shaped’ Mesogens, Gerhard Pelz &, Wolfgang Weissflog. Introduction Variants of polymorphism with SmCPA, conventional smectic (SmA, SmC) and nematic phases Polymorphism with polar biaxial SmA phases Direct transitions from the nematic to polar smectic or columnar phases Bent-core and calamitic mesogens – mixed with each other or covalently linked to each other Unusual properties of conventional smectic and nematic phases formed by bent-core mesogens Field-induced transitions from a non-polar phase to a polar phase Discussion Acknowledgement References Chapter 2: Physical Properties of banana liquid crystals, Antal Jákli, Chris Bailey & John Harden. Introduction Experimental Results Acknowledgements References Chapter 3: Atomistic-Resolution Structural Studies of Liquid Crystalline Materials Using Solid-State NMR Techniques: Solid-State NMR of Liquid Crystals, Akira Naito & Ayyalusamy Ramamoorthy. Introduction SLF State-Correlated 2D NMR Spectroscopy SC-2D NMR Spectra of Liquid Crystalline Samples Summary and Scope References Chapter 4: Separated Local Field NMR Spectroscopy in Columnar Liquid Crystals, S. V. Dvinskikh. Introduction 13C-1H separated local field NMRspectroscopy Summary Acknowledgements References Chapter 5: Biaxial nematic phases in thermotropic liquid crystals, K. Severing and K. Saalwachter. Introduction A Long-discussed Candidate Phase Biaxiality in Nematic Liquid-Crystalline Polymers Phase Biaxiality in Combined Disc-Rod Mesogens Biaxial Nematic Phases in Liquid Crystals Consisting of Banana Mesogens Organo-Siloxane Tetrapodes Summary References Chapter 6: NMR Study Of Self-Diffusion, Anatoly Khitrin. Introduction Collective Coherent Response Signals Gradient-Echo with Soft Excitation Pulse References Chapter 7: Structure and Dynamics of Thermotropic Liquid Crystalline Polymers by NMR Spectroscopy, Isao Ando and Takeshi Yamanobe. Introduction Structure and dynamics of crystalline liquid crystalline polyesters with flexible side chains Diffusion of rod like polymers in the thermotropic liquid crystalline phase by field-gradient NMR References Chapter 8: Recent Experimental Developments at the Nematic to Smectic-A liquid crystal phase transition, Anand Yethiraj Introduction Background: The Hierarchy of Theoretical Approximations Experiments Probing Mean Field Parameters Experiments Probing Crtitical Behaviour Experiments Probing Phase Transition Order The Landau-Peierls Instability in Smectics Summary

Blurb

Thermotropic Liquid Crystals: Recent Advances covers developments in the field of thermotropic liquid crystals and their functional importance. In addition it presents advances related to different sub-areas pertinent to this interdisciplinary area of research. This text brings together research from synthetic scientists and spectroscopists and attempts to bridge the gaps between these two areas.

Recent studies have reported a plethora of novel mesogenic molecules which triggered new interest in this area of research. Use of design concepts such as microphase segregation, non-covalent interactions, dipole-dipole interactions and shape anisotropy enabled the incorporation of any chemical structure into a liquid crystal. As a result, a range of exciting molecules such as columnar liquid crystals that lack side chains, liquid crystalline dendrimers, and unusually shaped amphiphilic molecules have been made. Characterization of these surprising molecules poses a tremendous challenge to existing physical techniques.

This comprehensive text has chapters covering the applications of high-resolution methods, such as solid-state NMR, that have been used to understand the high-resolution structure, dynamics, orientation, and orientational order of these molecules in various phases.

This book will prove to be an invaluable resource to students, researchers, and academics active in Chemistry, Material Science, and Nano-science programs. It will also be of interest to Scientists from industries that focus on this research.