Molecular Crystals and Liquid Crystals, Vol.443, 181-189, 2005
Synthesis and photoinduced alignment of photo-cross-linkable copolymer liquid crystals containing tolane side groups
Methacrylate copolymer liquid crystals (CPLCs) comprising photo-cross-linkable 4-(4'-methoxycinnamoyloxy)biphenyl (4MCB) side groups and 4-cyano- or 4-methyltolane side groups were synthesized. Thermally enhanced molecular reorientation behavior of CPLC films was investigated by irradiating with linearly polarized ultraviolet (LPUV) light and subsequent annealing. The exposure to LPUV light generated an axis-selective photoreaction of the 4MCB groups for all CPLC films. Thermally enhanced cooperative in-plane reorientation was observed for CPLC copolymerized with a 4-methoxytolane side groups and the generated birefringence was 0.25. However, out-of-plane reorientation was predominant when a comonomer with a 4-cyanotolane group was copolymerized.