Molecular Structure and Ordering in Liquid Crystals

Abstract

In an earlier paper1 we have discussed the variation of order parameter as a function of temperature, and the packing coefficient as a function of chain length for the homologous series of liquid crystals having symmetric and asymmetric molecules. Presently, we have studied the variation of thermal stability as a function of chain length for symmetric and asymmetric homologous series. The thermal stability increases as alkyl chain increases for symmetric homologous series. Clearly, they show exactly similar trend as observed for packing coefficients. We have also discussed the variation of order parameters with chain length at the transition temperatures for symmetric and asymmetric molecules. The order parameters have been theoretically evaluated for the two homologous series 4,4′-di-n-alkyloxyazoxybenzenes(symmetric) and p-(p-ethoxy-phenylazo)phenyl alkanoates(asymmetric). The results obtained are in good agreement with the experimental data.