Mixed Mesomorphism: Binary Liquid Crystal Systems Exhibiting Linear and Non-Linear Thermal Behaviour

Abstract

The number of binary systems are studied where one of the component is 4-Nitroben-zylidene-4′-n-heptyloxyaniline, which is polymesogenic exhibiting enantiotropic nematic and monotropic smectic mesophases. In all the systems studied the second component is either a Schiff f base or an ester. Two distinct trends are observed in these binary systems. When the second component possesses a strongly polar nitro terminal group the phase diagrams exhibit linear behaviour. However, the systems where the second component does not possess a strongly polar terminal group, the phase diagrams exhibit non-linear behaviour. In one of such binary system maxima is observed for smectic as well as nematic mesophases and an induced smectic mesophase is also observed. The monotropic smectic and nematic mesophases become enantiotropic even with small percentage concentration of either components in couple of the binary systems. The latent transition temperature is obtained by extrapolation method in one binary system. The UV and IR spectral study was carried out for examining the possibility of charge-transfer complex formation in the binary systems.