........ published in NEWSLETTER # 52
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........ published in NEWSLETTER # 52
THE MOLECULAR DYNAMICS OF LIQUID CRYSTALS
by Professor G.R. Luckhurst, University, Southampton (U.K.) and Professor C.A. Veracini, University, Pisa (Italy)
Liquid crystals have proved to have a wide range of important technological applications including electro_optic display devices, detergency and high tensile strength polymers. One consequence of these applications has been a major effort, largely successful, in determining their static properties and understanding the results of such measurements. In contrast the dynamic behaviour of liquid crystals is less well understood. However, in recent years there have been considerable advances in the application of experimental techniques to probe the molecular dynamics in liquid crystals and in the development of theories for such dynamics.
This book (NATO ASI SERIES C431) provides the first coherent account of both the experimental and theoretical study of the dynamic processes undertaken by molecules in liquid crystal phases. It was based on lectures presented at a particularly stimulating NATO Advanced Study Institute held at Il Ciocco, Barga, Italy in September 1989. This brought together leading scientists from a wide range of backgrounds reflecting the multidisciplinary nature of the subject. The Institute revealed the need for a book covering all aspects of molecular dynamics in liquid crystals and written in a pedagogical manner. The lectures were subsequently revised and assembled in a logical and consistent framework. It is to be expected, therefore, that this book will serve as the standard text for many years to come.
The first Chapter presents a valuable overview of the dynamics which occur in liquid crystals and describes how these may be probed using a range of spectroscopic techniques. The next five Chapters present the theoretical background necessary to understand the molecular dynamics and the influence of the long_range order characteristic of liquid crystals on the motion. This includes both analytic theory and the application of numerical simulation techniques. NMR spectroscopy has been shown to be a particularly powerful technique in the study of the dynamic as well as the static properties of liquid crystals and so four Chapters are devoted to the many aspects of this branch of spectroscopy. In addition to studying pure systems it is also possible to use probe molecules to explore the dynamic properties of the system. The general philosophy of spin probes is described in a Chapter which serves as an introduction to four Chapters which deal with the use of ESR spectroscopy to investigate molecular dynamics in liquid crystals both thermotropic and lyotropic. In addition, particular attention is paid to relating the results to theory. Other techniques which are used to study dynamics in liquid crystals include infrared and Raman spectroscopy, dielectric relaxation and neutron scattering. A Chapter is devoted to each of these three techniques which are illustrated with the results of typical investigations and their interpretation. The final four Chapters are concerned with studies of the dynamics in liquid crystal polymers, but more especially in lyotropic systems including bilayer membranes. In addition the use of fluorescence depolarisation techniques for lyotropic systems is given particular attention.
It should be clear that this book contains something for everybody, an introduction to a wide range of experimental techniques for the study of molecular dynamics in liquid crystals; the results of such measurements for typical mesomorphic systems and the interpretation of these results using both analytic theory and computer simulation.
Reference books: B166, B229, B290, C141, C431