MOLECULAR-PROPERTIES OF SOME NEMATIC LIQUIDS .2. REFRACTIVE-INDEX AND ORDER PARAMETER

The refractive indices and densities of a number of 4,4 prime -disubstituted phenyl benzoates and the Merck nematic phases ZLI 1052 and ZLI 389 are reported as functions of temperature in the nematic and isotropic phases. Also, two isomers of 4,4 prime -disubstituted phenyl thiobenzoates are investigated. Comparison of Vuks model with that of the Jeu-Bordewijk is made. Based on these models and some assumptions, the molecular polarizability anisotropies are calculated. Then the order parameters are deduced using Vuks model. The effect of the terminal substituents and central groups on the order parameter is discussed. The isomeric compounds have nearly the same order parameter. For compounds with similar chemical framework, the order parameters in the case of nitriles are higher than in the case of alkoxides. Also, it is higher in the case of alkyls than in the case of alkoxides. The effect of the esters and thioesters on the order parameter is nearly identical.