DIRECTOR DISTORTION IN A NEMATIC WETTING LAYER

Nematic liquid-crystal wetting at a solid interface presents particula rly interesting features when the nematic director orientation at the solid interface is antagonistic to that favoured by the emerging nemat ic-isotropic interface. We have used the Landau-de Gennes theory of an inhomogeneous liquid crystal to make a quantitative study of this phe nomenon, for the case when the solid surface favours homeotropic ancho ring but the nematic-isotropic surface favours planar anchoring. By ge neralizing the theory of Sheng to allow spatial variation of the direc tor, we find a richer surface phase diagram exhibiting a prewetting li ne or boundary transition shifted from that discussed by Sheng, as wel l as a transition between two nematic wetting phases, at which the wet ting layer director profile changes from a homeotropic to a distorted texture.