Measurement of the Surface Tension of CBOOA

In continuation of our previously reported experimental studies on the surface tension of liquid crystals, measurements have been carried out on p-cyanobenzylidene p'-n-octyloxyaniline (CBOOA) in its smectic A, nematic and isotropic phases. The surface tension-temperature (γ-T) characteristic shows a positive slope throughout the smectic phase, changes sign at the smectic A-nematic transition, remains negative over the entire nematic range and again reverses sign immediately after the nematic-isotropic transition, the positive slope now continuing for a few degrees in the isotropic phase. These trends are compared with the theoretical predictions of Croxton and Chandrasekhar.