Phase Transition Studies in Mixed Polymesomorphic Liquid Crystals with Cholesteric and Smectic A Phase

Cholesteric mesomorphism was induced in a polymesomorphic liquid crystal with nematic and smectic A phases by mixing it with a low pitch cholesteric. A variety of mixtures for a wide range of concentrations were studied. It was observed that the addition of cholesteric liquid crystal disrupts the smectic phase of the parent polymesomorphic liquid crystal. The measured valuses of ultrasound velocity and specific volume and their related parameters were found to exhibit anomalies near each of the phase transitions. The mean interaction parameter \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \alpha $\end{document} was estimated for different mixtures and was found to decrease with increasing concentration of cholesteric liquid crystal in the mixture. It was observed that smectic A‐cholesteric transition becomes second‐order at a particular concentration in agreement with the theoretical predictions.