THIN-FILMS OF LIQUID-CRYSTALLINE POLYMERS AS ALIGNMENT LAYERS FOR LIQUID-CRYSTAL DISPLAYS

Thin films of main-chain and side-chain liquid crystalline polymers (LCP) formed by spincoating were investigated. The self-aligning effect of the rubbed main-chain LCP thin film after thermal annealing was observed. The thermal annealing at the onset temperature of the transition from the solid to liquid crystalline phase brings large optical anisotropy (delta n > 0.07) to the main-chain LCP film but not to the side-chain LCP film. The effect of rubbing and annealing on the surface morphology of the main-chain LCP film is also discussed by means of a scanning electron microscope (SEM) and atomic force microscope (AFM). The surface roughness of the main-chain LCP film increased drastically after the annealing because of the recrystallization. Nematic liquid crystals orient uniformly even on such a rough surface when the main-chain orientation of the LCP is in the rubbing direction. This indicates that the main-chain LCP can be used as an alignment layer with high performance for LCDs.