Phase Transition Studies and Thermodynamic Parameters of Four Members of nO.m Series—A Dilatometric Study

Abstract

Density measurements are carried out on four alkoxy benzylidene alkyl anilines, viz., N-(p-n-methoxy/ethoxybenzylidene)-p-n-dodecyl and tetradecylanilines, 1O.12, 1O.14, 2O.12, and 2O.14. The first three compounds exhibit monovariant nematic phase while the last compound exhibits nematic and smectic-A phase with variable thermal ranges. The density measurements infer the first order nature for Isotropic to nematic (Iso-N) phase transformation while the nematic to smetic-A (N-SmA) transition as weak first order. Thermal expansion coefficient α estimated from density ρ is utilized for the computation of thermodynamic parameters of above liquid crystalline compounds. The temperature variation of different thermodynamic parameters like Moelwyn-Hughes parameter, reduced volume, reduced compressibility, isothermal, isochoric, and isobaric Gruneisan parameters, etc., are estimated. The results are compared with the available data in literature of other compounds.