Unified model of the smectic-A, nematic, and isotropic phases for bulk, interfaces, and thin films. II. Interfaces and thin films

Using material parameters determined by bulk behavior, and the lattice model presented previously by us, we study interfacial and thin-film phenomena in the mean-field approximation. The effects of free and solid surfaces on orientational ordering for the isotropic phase are found to depend on the details of the intermolecular interaction and, sufficiently far above the supercooling limit, the decay length is on the order of a molecular dimension. For some materials, we find smecticlike thin films at temperatures above the bulk nematic-isotropic transition, enhanced orientational ordering, and the possibility of multiple smecticlike phases