Liquid crystal solutions at infinite dilution: Enthalpy–entropy compensation of solutes transfer properties between phases

Abstract

Careful gas chromatographic (GLC) studies provide thermodynamic data for insights into solution processes in non-volatile solvents. In this study, thermodynamic properties of solutes at infinite dilution of several liquid crystals measured by GLC were examined. The enthalpy and entropy of solutions in mesophases were positive and higher than those of isotropic stationary phases. When solute transfer enthalpy (ΔHtr) and transfer entropy (ΔStr) between two phases of a liquid crystal were examined, remarkable enthalpy–entropy compensation relations were observed. This was because the small values of transfer free energy. Both ΔHtr and TΔStr had large values and were almost equal, resulting in small values of transfer free energy. The temperature dependency of the disorder parameter in Flory's theory of liquid crystals was used to explain high values of the enthalpy and entropy of solution.