Studies on Controlling Factors of Discotic Liquid Crystals of Vertical Alignment

Abstract

A "sea and island" texture appears in a discotic liquid crystal layer prepared by coating discotic compounds on a rubbed vertical alignment layer. We found that the texture was caused by tilted alignment of discotic liquid crystals at the air interface by using polarized microscopic observation of ultra thin cross-sectional cut pieces of the polymerized discotic liquid crystal films. Based on the knowledge, we synthesized new compounds to promote vertical alignment in order to control the pretilt angle at the air interface. We have achieved uniform vertical aligned structure by adding a small amount of the compounds to discotic liquid crystals.