【作者】 于涛；

【导师】 宣丽；

【作者基本信息】 中国科学院研究生院（长春光学精密机械与物理研究所） ， 凝聚态物理， 2004， 博士

【摘要】 液晶显示器以其平板性、携带方便、功耗低、视力保健的优点越来越受青睐，已能与阴极射线管显示器平分国际市场，并正在已继续上升的势头发展。液晶显示器产业化以来一直采用摩擦法的取向处理。然而在摩擦过程中会引起静电、尘埃造成成品率下降，最严重的是摩擦产生的沟痕使微显示器件的显示质量降低。因此光控取向技术近年来引起人们的极大关注，它不仅能克服摩擦取向法的缺点，而且可以进行微区取向控制，扩展液晶光学器件的应用范围。 光控取向的原理是在线偏振紫外光作用下，光敏聚合物侧链定向光交联，出现分子链段的指向有序分布，从而诱导液晶分子排列。光控取向技术瓶颈问题是稳定性差，其根本原因是光敏高分子空间位阻太大，定向交联的反应度太低，有效解决方法应是降低位阻，提高定向交联度和取向膜分子链段的有序度。本文首次提出了用肉桂酸单体替代光敏高分子进行四中心定向聚合的光控取向方法，并在这一原创思想之下，对光控取向技术进行了系统性探索和革新。 自行设计和合成了联苯双肉桂酸酯(BPDE)、双酚A双肉桂酸酯(BADE)、六氟双酚A双肉桂酸酯(6F-BADE)三种单体材料；从分子结构刚性入手解决了单体薄膜易结晶问题，改善了单体成膜性；分别用紫外吸收光谱和红外光谱分析了光化学反应过程，反应速率和反应度；发现氟的引入会明显提高光聚合反应速率，并改变表面张力极性；测得BPDE和BADE为水平取向膜，在90℃加热30分钟仍保持完好的排列特性，已达到一般液晶器件制作过程中热处理工艺的要求；另外六氟双酚A双肉桂酸酯光控取向膜诱导液晶分子垂直排列，具有120℃的热稳定性，非常适合做宽视角的多畴垂直显示模式；采用红外二向色吸收分析了单体光控取向膜分子链段分布的各向异性，提出定量计算取向膜有序度的方法，BPDE、BADE单体光控取向膜有序度相比肉桂酸聚合物光控取向膜来说具有大幅度提高。 本文是物理和化学相互融合的结晶，对于完善光控取向技术，使其走上实用化具有重要贡献。更多还原

【Abstract】 Liquid crystal device(LCD) has attracted more interest due to flatness portability, lower power consumption and eyesight protection .The share of LCD in the international display field will close to that of CRT and keep increasing tendency. The surface rubbing technique has been commonly used for fabricating liquid crystal display panels by LCD industry. However, the rubbing process may cause electrostatic charge, dust or scratches that tend to destroy the display quality. Non-rubbing technique, photoalignment technique attracts more people’s attention. Photoalignment is promising for overcoming the drawbacks caused by the rubbing process and providing multi-domain structure for widening the viewing angle and a new way for liquid crystal optic devices.The mechanism of photoalignment is that the selective photoreaction broke out on the surface of the polymer under the irradiation of linearly polarized ultraviolet light (LPUV). The orientational alignment of molecular chains induces LC alignment in a certain direction. Poor thermal stability as a bottleneck has limited the development of liquid crystal photo-alignment technique. The intrinsic reason is that the photosensitive polymer has large space resistance and decreases the reaction degree of the directional photo-polymerization. The effective solution is focused in the increase of orientational order of photo-alignment film. In this paper, the alignment method of Four-center linear polymerization using cinnamate monomers was put forward and the photoalignment technique was searched in details and renovated.The monomer structures were designed. Biphenyldicinnamate ester (BPDE) , bisphenol A dicinnamate ester (BADE) , and hexafluorobiphenol A dicinnamate ester (6F-BADE) were synthesized in our laboratory. Changing the rigidity of molecular structure solved the crystallizing problem in the process of spin-coated monomer films and a good film in quality was fabricated. The photochemical reaction rate and degree were measured by UV-visible and infrared absorbance spectra. When the fluorine atoms were grafted in the monomer structure, the reaction degree as well as the reaction rate was enhanced obviously. The photo-crosslinking films of BPDE and BADE can induce homogeneous alignment of liquid crystals. Uniform alignment was kept even curing at 90℃ for 30 minutes and the thermal stability was suit to the general fabrication of liquid crystal devices. Photo polymerized films of 6F-BADE can align liquid crystal in homeotropic alignment and the thermal stability reaches 120℃. It suggests that the photo polymerized 6F-BADE was fitted to fabricate multi-domain vertical alignment, a LC display mode with broad viewing angles. The orientational orders of the photoaligned polymer films were analyzed by polarized Fourier transition infrared (FT-IR) spectra. The quantitative calculation was made by the infrared dichroic absorption. The results indicate that the orientational orders of monomer photoalignment films of BPDE, BADE were much larger than that of polymer (cinnamate) photoalignment films.In summery, this work was successfully performed based’ on the elementary knowledge of physics and chemistry. It has a valuable contribution to the improvement and the application of the photo-alignment technique.更多还原