Thermal variation of surface tension at liquid crystal-isotropic liquid interface

The surface tension of two nematic liquid crystals bounded by an isotropic liquid (glycerin) was measured as a function of temperature. A spinning drop technique was used for the measurements. Unlike monotonically decreasing dependence found in most isotropic liquids, the surface tension - temperature characteristic showed more than one region with positive slope in the nematic phase. A sharp increase in surface tension was observed near the nematic-isotropic transition temperature. The results obtained are in qualitative agreement with the theoretical predictions of Croxton and Chandrasekhar.