Alignment of nematic butoxybenzilidene octylaniline by surface-relief gratings

Abstract
The effect of surface-relief gratings on alignment of the nematic phase of butoxybenzilidene octylaniline has been studied for gratings of 1-μm and 300-nm period with grating depth from 22 to 410 nm. A planar-to-homeotropic alignment change was observed on flat surfaces and interpreted quantitatively by a model invoking the entropy change due to smectic short-range order imposed by the surface in the homeotropic state. The alignment change was suppressed by gratings of sufficient depth or short enough period.