The synthesis of new main-chain liquid crystalline polymers as materials for non-linear optics

Abstract

The work described in this thesis is concerned with the synthesis of new main-chain liquid crystalline polymers. A new series of liquid crystalline monomers based on an unsymmetrically disubstituted stilbene containing alcohol and carboxylic acid, groups has been synthesised and characterised. The monomers could be polymerised in the presence of N-N'-dicyclohexyl carbodiimide and 4-pyrolidinopyridine to give a novel class of main-chain liquid crystalline polymers which may have potential applications in the field of non-linear optics. The effect of the length of the flexible spacer units on the liquid crystalline phase transitions is also discussed. The thesis is divided into four chapters. In the first chapter the introduction and background of (i) liquid crystals and liquid crystalline polymers, (ii) non-linear optical materials, (iii) polyesters and step-growth polymerization as it relates to this work, is discussed. The second chapter describes the experimental details for the synthesis, characterization and polymerization of the monomers. In die thud chapter the chemistry and physical characterization of the main-chain liquid crystalline polymers are described and discussed. The conclusions reached are summarised in chapter four and a few suggestions for extending the work described in this thesis are put forward.