Measurement of the interfacial tension between coexisting isotropic and nematic phases of a lyotropic polymer liquid crystal

The interfacial tension and molecular alignment were studied for the interface between coexisting isotropic and nematic phases of a toluene solution of poly(n-hexyl isocyanate). A polarizing microscopic observation revealed that the nematic phase in the vicinity of the interface is aligned homogeneously, i.e., the director is parallel to the interface, consistent with the prediction of Doi and Kuzuu for rodlike polymer solutions. The value of the interfacial tension is 0.024 dyn/cm, as compared with the theoretical value (=0.011 dyn/cm).