Photo-dimerization of a chalcone-based side chain polymer for the alignment of ferroelectric liquid crystals

Abstract

The alignment and optical properties of ferroelectric liquid crystal cells, having alignment films of a chalcone-based side chain polymer treated by linearly polarized UV irradiation were investigated. The long absorption band of the UV/Vis spectra gradually decreased and the FTIR spectra shifted as the irradiation times increased, indicating that cyclo-addition and isomerization reactions of the chalcone-based side chains occurred. UV dichroism demonstrated anisotropic changes in the alignment films, with a maximum at low exposure energy (0.5 J cm 22 ). Liquid crystal molecules were aligned perpendicular to the polarization direction of the linearly polarized UV radiation. The azimuthal anchoring energy of liquid crystal E7 on a chalcone-based side chain polymer surface increased with exposure energy. Well aligned defect-free cells and high contrast ratio were achieved with irradiation of longer than 5 min; the geometric conditions for a stable C2 structure may be satisfied at low temperature with slowly cooling.

Preparation of polyoxometalate-chalcone hybrid and its photo-polymerization property

“…查耳酮及其衍生物, 作为黄酮类化合物的一种, 通常是由芳香醛酮发生羟醛缩合而成, 在有机染料、 生物医药等领域具有广泛的应用 [23,24] . 同时, 由于查 耳酮结构中含有紫外光敏感的,-不饱和羰基, 能够 在紫外光照下快速地发生[2+2]环加成反应, 因此, 查耳酮及其衍生物也常被用作为紫外光敏材料 [25] . [28] ; 再通过传统一锅法 [29] , 将 Anderson cluster with chalcone molecules.…”