Liquid crystal alignment on the two-directionally processed substrates: Comparison of mechanical rubbing and plasma beam alignment

Two-directional plasma beam processing or mechanical rubbing was used to investigate the orientations of liquid crystal (LC) molecules on polyimide (PI) and hydrogenated amorphous carbon films. Two-directional plasma beam processing exhibits better homogeneity than two-directional mechanical rubbing in the LC alignment. In the two-directional mechanical rubbing treatment, grid-like texture appears on the PI film, supporting that the direction of each rub is memorized. A phenomenon of rewriting LC alignment exhibits in the two-directional plasma beam processing. The effect of the first plasma beam scanning is erased by the second one in the two-directional plasma beam processing.