Photoinduced Cooperative Reorientation in Photoreactive Hydrogen-Bonded Copolymer Films and LC Alignment Using the Resultant Films

Abstract

Polymethacrylate copolymers, which have hexamethylene spacer groups terminated with 4-oxycinnamic acid, 4-oxybenzoic acid, and 4-(4′-oxyphenyl)benzoic acid in the side chain, were synthesized, and the photoinduced cooperative molecular reorientation of thin films was demonstrated using linearly polarized ultraviolet (LPUV) light and subsequent annealing. Adjusting the exposure doses can control the molecular reorientation direction both perpendicular and parallel to the polarization E of LPUV light. Tuning the copolymer composition adjusted the optical birefringence of homogeneously reoriented films between 0.095 and 0.178. Finally, adjusting the exposure doses achieved uniform alignment control of low-molecular liquid crystals (LCs) on the molecular reoriented copolymer films both perpendicular and parallel to the polarization E of LPUV light.