Growth of Smectic B (Crystal) and Phase Transitions in Liquid‐Crystalline PBnA (n = 4, 5, and 6) Compounds

Abstract

Abstract Thermal microscopy, calorimetric (DSC) and dilatometric investigations are reported in three liquid‐crystalline compounds of n (4‐ n ‐phenylylbenzylidene) 4‐ n ‐alkylaniline series viz., PB n A for n = 4, 5, and 6. They exhibit nematic, smectic B (cryst) and smectic E (monotropic) polymorphism. Effective role of terminal phenyl end chain is discusscd for the occurrence of 3D‐ordered smectic B and smectic E phases. Density jumps and associated volume expansion coefficient anomaly infer first order nature of isotropic to nematic (IN) and nematic to smectic B (NB) transitions. Exponental growth of three‐dimensional hexagonal positional correlations estimated in the vicinity of nematic to smectic B transition through the β exponent infers the Van der Waals type of molecular interactions. Pressure dependence of transition temperatures are estimated, IN and NB transitions and thermal stablity are discussed.