Influence of Molecular Structure on Liquid Crystalline Properties and Phase Transitions in Mixed Liquid Crystals

Abstract

Abstract A number of binary systems comprising a liquid crystalline Schiff's base, viz. p-acetoxybenzal-p-phenetidine and a non-liquid crystalline Schiff's base are studied. In all these cases, the liquid phase, be it anisotropic or not, is a single homogeneous phase. There is no indication of two distinct liquid phases, one anisotropic and the other isotropic, coexisting side by side over a range of temperature, for a binary system of a given composition. The shape of the transition lines in the phase diagrams of the binary mixtures is dependent on the type of the admixed non-mesomorphic component. In the case of systems comprising isomorphous components, the transition lines are almost linear. If the molecules of the two components differ in shape and size, owing to the difficulty in packing themselves together the transition lines of such binary systems exhibit a concavity. When the admixed component is altogether an odd molecule in shape, size and structure, compared to the mesomorphic component, the ...