Surface tension of some liquid crystals in the cyanobiphenyl series

The temperature dependence of the surface tension was measured by the penda nt drop method for four compounds from the homologous series of alkylcyanob iphenyls (nCB), in the nematic liquid crystal and isotropic phases, For SCB (oclylcyanobiphenyl) the temperature dependence was also measured in the s mectic range. Not very close to the Isotropic transition temperature, and w ith the exception of 8CB, the surface tension decreases with increase in te mperature in the nematic range. A downward jump at the transition temperatu re was observed for all liquid crystals studied. The shape of the drop in t he smectic A phase of 8CB gives indications of stratification in a system o f terraces.