Orientations of side chains and adsorbed liquid crystal molecules on a rubbed polyimide surface studied by optical second harmonic generation - art. no. 051706

Surface second harmonic generation was used to obtain approximate orientati onal distributions of the side chains and the adsorbed liquid crystal (LC) molecules on a rubbed side-chain polyimide surface. Both the side chains an d the LC molecules appear to be well aligned in the rubbing direction but t ilted away from the surface in the antirubbing direction. The latter yields a negative pretilt angle in a homogeneously aligned LC film sandwiched bet ween two such surfaces. The side chains and the LC molecules, however, have antiparallel orientations at the surface.