STRUCTURE IN A CONFINED SMECTIC LIQUID-CRYSTAL WITH COMPETING SURFACEAND SAMPLE ELASTICITIES

We report on studies using the x-ray surface forces apparatus (XSFA) t o compare the structure of a liquid crystal confined between hard surf aces and, for the first time, between soft surfaces that can deform du e to the stresses imposed by the confined fluid. We find that the alig nment of smectic domains in confined films depends critically on both the shape and compliance of the confining walls or surfaces ''Soft sur faces'' exhibit a critical gap thickness of 3.4 mu m for the liquid cr ystal studied at which maximum alignment occurs, while ''hard surfaces '' do not exhibit gap-dependent alignment.