Photoinduced Surface Alignment: The Role of Liquid-Crystalline Order

Abstract

The optical control of surface alignment was investigated, using azo-dye doped polyimide films as photosensitive material. The kinetics of the realignment of the easy axis was measured in isotropic, nematic and smectic A phases. It is demonstrated that the light-induced realignment of the dye molecules at the polymer-liquid crystal interface is strongly influenced by the presence of the liquid-crystalline order. A simple model is presented, which accounts qualitatively for the experimental observations.

Key Words:

• photoalignment
• dye-doped polymers