Liquid-crystal orientation induced by polymeric surfaces

Abstract

Orientation induced on liquid crystals by plane polymeric surfaces has been investigated. Thin polymerized films were prepared from hexamethyl disiloxane, methyl methacrylate, and isobutylene by a glow‐discharge process; from γ glycidoxy‐propyl‐trimethoxy silane by dip coating; from polytetrafluoroethylene by sputtering. Critical surface tension γ_C of each film and surface tension γ_LV of various pure nematic compounds were measured, and orientation induced by the former on the latter was tested. When γ_C is very low, in front of γ_LV, very good homeotropic structure is observed. Conversely, high‐energy surfaces seem to induce homogeneous structure.