Measurements of the interfacial tension between nematic and isotropic phase of some cyanobiphenyls

The interfacial tension ?eq between nematic and isotropic phases of some cyanobiphenyls has been measured by using the sessile drop method. Values of ?eq ranging from 0.7 × 10-2 to 1.8 × 10-2 erg/cm2 are obtained. In a recent paper we measured the optical reflectivity coefficients at the nematic-isotropic interface of 7CB. By using these coefficients and the measured value of ?eq we can obtain the experimental value of the intrinsic thickness of the nematic-isotropic interface of 7CB. This thickness is compared with the one predicted by the Landau-De Gennes theory. A satisfactory agreement between experimental and theoretical values is found.