UV-Induced Stable Planar Alignment of Nematic Liquid Crystals Using a Polypropyleneimine Dendrimer Having a Mesogen Consisting of Cinnamate and Azobenzene Moieties

A liquid crystalline dendrimer having a cinnamate mesogen containing an azobenzene moiety (D-6AC2) was prepared as an alignment agent of nematic liquid crystals for a planar homogeneous alignment. D-6AC2 is a thermotropic liquid crystal showing smectic phases. A mixture of ZLI-4792 with 1wt% of D-6AC2 exhibited a homeotropic alignment. After UV irradiation of the same sample, the schlieren texture due to a planar orientation was observed, and the texture was maintained even after 133 days. Thus D-6AC2 can induce the stable planar alignment of NLC upon UV irradiation. Furthermore, D-6AC2 could induce a planar homogeneous alignment by polarized UV light irradiation.