Thermodynamic Description of Liquid Crystalline N(p-n-Alkyloxybenzyliden)-p’-Toluidines with Organic Solvents

Abstract

Solubility polytherms of nematic (smectic-nematic) N(p-n-alkyloxybenzyliden)-p’-toluidenes (n-alkyl = C4H9, C9H19, C10H21) in organic solvents have been studied. Thermal analysis, visual-polythermal and solubility methods were used. The solution enthalpies of these mesogens in 8 solvents (n-hexane, n-heptane, benzene, p-xylene, cyclohexane, methylcyclohexane, ethanol, n-propanol) were determined. To calculate the solubility polytherms, thermodynamic methods based on the Hildebrand solubility parameters were used. The advantage of the proposed calculation method is that it requires a minimum of experimental parameters (fusion enthalpy and melting temperature of pure mesogen) and the data obtained from the structural formula (group contribution increments) of a mesogen to evaluate its solubility polytherms.