Orientation of liquid crystals by surface coupling agents

Uniformly oriented thin liquid-crystal layers are required for most liquid-crystal device applications and physical investigations. Usual methods for obtaining orientation rely on a substrate interface which has an orienting action on the liquid-crystal molecules. In previously described methods the orienting interfaces degrade chemically with time, thereby generating a corresponding degradation of the liquid-crystal orientation. In the present work, silane surface coupling agents are used to obtain chemically stable interfaces and a wide variety of liquid-crystal orientations.