Antiferroelectricity and related chirality induced frustrations in smectic liquid crystals : effect of molecular structure

Abstract

This work was devoted to synthesis of new antiferroelectric liquid crystalline materials in series of chiral I-methylheptyI4'-(4-n-alkyloxybenzoyloxy)biphenyl-4-carboxylates. 9 new types of materials were synthesised and their chemical, mesomorphic and electrooptical properties were investigated in the homologous series.The chemical structure of each material synthesised was proved through IHNMR and IR spectroscopy studies, mass spectrometry, optical rotation measurements and analytical HPLC technique.The mesomorphic properties of the final products were investigated by the DSC method and textural observations in polarising light microscope. The electrooptical experiments were done in thin planar cells by applying AC triangular wave field of various voltages and frequencies. The electrooptical response measured was plotted as a function of the external voltage and the resulting curves were analysed in detail. Apart from the investigation into mesomorphic behaviour of the compounds prepared, the effect of V -shaped switching was described for some of the homologues. The switching parameters were determined and conclusions were reached on the origins of the V -shaped electrooptical response.The studies on a new type of the twist grain boundary phase with local anti ferroelectric structure were described in separate chapter

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