基于聚酰亚胺的液晶光控取向研究
发布时间：2019-01-01 21:43
【摘要】：随着液晶材料在显示领域的广泛应用,摩擦法作为目前常用的制备液晶定向层的方法,由于其存在的严重缺点,目前已越来越不适用,探索一种新的液晶取向技术以取代摩擦取向技术是未来液晶显示技术的发展需要。光控取向技术以其设备简单、可以对液晶分子取向进行微观控制等优点成为目前为止最有希望取代摩擦取向技术的非接触性取向技术。本文采用365nm紫外光曝光、线偏振457nm激光垂直照射及两束正交圆偏振光干涉等实验手段,用含偶氮基团的聚酰亚胺聚合物制备取向层,以涂有取向层的玻璃基板、用两基板组成的空液晶盒及灌有E7液晶的液晶盒为实验对象,通过带有正交偏振片的CCD装置观察外光场对样品取向的改变,通过观察到的实验现象分析总结基于聚酰亚胺取向层的液晶光控取向特性。实验发现,紫外光的照射会使偶氮基团发生顺反异构反应,吸收光能变为顺式结构,使得聚合物分子转动,垂直于基板表面重新取向,液晶分子由于其与聚合物分子之间的相互作用也会顺着聚合物分子长轴重新取向。用线偏振457nm激光照射液晶盒时,偶氮基团吸收光能打破平衡状态,发生顺反异构反应,变为反式结构且往垂直于偏振光偏振方向的方向转动,使得聚合物分子在垂直于偏振光偏振方向的方向沿面重新取向排列,由于与聚合物分子之间的相互作用,液晶分子也将也液晶盒表面排列,且液晶指向矢与线偏振光偏振方向垂直。同时实验还发现,有液晶的样品其取向程度要比没有液晶时好等多,所观察到的图像明暗对比度没有液晶是大很多,并且光控取向响应时间也比没有液晶时短近十倍。最后还用两束正交的圆偏振457nm激光在空液晶盒和灌有液晶的液晶盒表面干涉,成功制备出了全息偏振光栅,用632nm激光探测发现灌有液晶的液晶盒的衍射光斑比空液晶盒造成的衍射光斑亮很多,表明虽然空液晶盒也可以制备全息光栅,但灌入液晶后制备的光栅效果更好。此外,将样品加热到一定温度可以擦出外光场对液晶的写入。以上实验结果说明基于该聚酰亚胺取向层的液晶光控取向不仅受光的波长控制,还受光的偏振方向控制。本论文的研究成果除了在显示领域具有一定应用价值,也同样适用于光通信液晶器件的开发,如光功率控制器件及偏振控制器件等;并且对于光控取向技术应用于新型取向层的制备及光信息存储具有一定的参考作用。
[Abstract]:With the wide application of liquid crystal materials in the field of display, friction method, as a commonly used method of preparing liquid crystal directional layer, has become more and more inapplicable because of its serious shortcomings. It is necessary to explore a new liquid crystal orientation technology to replace the friction orientation technology. The optically controlled orientation technology has become the most promising non-contact orientation technique to replace the friction orientation technique because of its simple equipment and the advantages of microcosmic control of the orientation of liquid crystal molecules. In this paper, the orientation layer of polyimide polymer containing azo group was prepared by means of 365nm ultraviolet light exposure, linear polarized 457nm laser vertical irradiation and two beams of orthogonal circular polarized light interference, and the glass substrate was coated with an azo group. Using the empty liquid crystal cell composed of two substrates and the liquid crystal cell filled with E7 liquid crystal as the experimental object, the change of the orientation of the sample was observed by the CCD device with orthogonal polarizer. The optical orientation characteristics of liquid crystal based on polyimide orientation layer were analyzed and summarized by the observed experimental phenomena. It was found that UV irradiation would result in cis-isomerization of azo groups and the conversion of absorption energy into cis structure, which would make the polymer molecules rotate and reorientate perpendicular to the surface of the substrate. Liquid crystal molecules also reorient along the long axis of polymer molecules because of their interaction with polymer molecules. When a linearly polarized 457nm laser is used to irradiate the liquid crystal cell, the absorption energy of the azo group breaks the equilibrium state, and the cis-trans isomerization reaction takes place, which turns into a trans structure and rotates perpendicular to the polarization direction of the polarized light. The polymer molecules are realigned in the direction perpendicular to the polarization direction of the polarized light, and because of the interaction with the polymer molecules, the liquid crystal molecules will also be arranged on the surface of the liquid crystal cell. The liquid crystal direction vector is perpendicular to the polarization direction of linear polarized light. At the same time, it is found that the orientation of the sample with liquid crystal is much better than that without liquid crystal, the contrast of the observed image without liquid crystal is much larger, and the response time of the light-controlled orientation is about ten times shorter than that without liquid crystal. Finally, holographic polarization gratings were successfully fabricated by interference of two orthogonal circularly polarized 457nm lasers on the surface of empty liquid crystal cell and liquid crystal cell filled with liquid crystal. The diffraction spot of the liquid crystal cell filled with liquid crystal is much brighter than that of the empty liquid crystal cell by 632nm laser detection, which indicates that although the holographic grating can also be prepared by the empty liquid crystal cell, the effect of the grating prepared after pouring the liquid crystal cell is better than that of the empty liquid crystal cell. In addition, heating the sample to a certain temperature can wipe out the external light field to write liquid crystal. The experimental results show that the optical orientation of the liquid crystal based on the polyimide orientation layer is not only controlled by the wavelength of the light, but also by the polarization direction of the light. In addition to the application value in the field of display, the research results of this paper are also suitable for the development of optical communication liquid crystal devices, such as optical power control devices and polarization controllers. It can be used as a reference for the fabrication and storage of optical information of new type orientation layer using optically controlled orientation technology.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O633.2;O753.2
本文编号：2398137
[Abstract]:With the wide application of liquid crystal materials in the field of display, friction method, as a commonly used method of preparing liquid crystal directional layer, has become more and more inapplicable because of its serious shortcomings. It is necessary to explore a new liquid crystal orientation technology to replace the friction orientation technology. The optically controlled orientation technology has become the most promising non-contact orientation technique to replace the friction orientation technique because of its simple equipment and the advantages of microcosmic control of the orientation of liquid crystal molecules. In this paper, the orientation layer of polyimide polymer containing azo group was prepared by means of 365nm ultraviolet light exposure, linear polarized 457nm laser vertical irradiation and two beams of orthogonal circular polarized light interference, and the glass substrate was coated with an azo group. Using the empty liquid crystal cell composed of two substrates and the liquid crystal cell filled with E7 liquid crystal as the experimental object, the change of the orientation of the sample was observed by the CCD device with orthogonal polarizer. The optical orientation characteristics of liquid crystal based on polyimide orientation layer were analyzed and summarized by the observed experimental phenomena. It was found that UV irradiation would result in cis-isomerization of azo groups and the conversion of absorption energy into cis structure, which would make the polymer molecules rotate and reorientate perpendicular to the surface of the substrate. Liquid crystal molecules also reorient along the long axis of polymer molecules because of their interaction with polymer molecules. When a linearly polarized 457nm laser is used to irradiate the liquid crystal cell, the absorption energy of the azo group breaks the equilibrium state, and the cis-trans isomerization reaction takes place, which turns into a trans structure and rotates perpendicular to the polarization direction of the polarized light. The polymer molecules are realigned in the direction perpendicular to the polarization direction of the polarized light, and because of the interaction with the polymer molecules, the liquid crystal molecules will also be arranged on the surface of the liquid crystal cell. The liquid crystal direction vector is perpendicular to the polarization direction of linear polarized light. At the same time, it is found that the orientation of the sample with liquid crystal is much better than that without liquid crystal, the contrast of the observed image without liquid crystal is much larger, and the response time of the light-controlled orientation is about ten times shorter than that without liquid crystal. Finally, holographic polarization gratings were successfully fabricated by interference of two orthogonal circularly polarized 457nm lasers on the surface of empty liquid crystal cell and liquid crystal cell filled with liquid crystal. The diffraction spot of the liquid crystal cell filled with liquid crystal is much brighter than that of the empty liquid crystal cell by 632nm laser detection, which indicates that although the holographic grating can also be prepared by the empty liquid crystal cell, the effect of the grating prepared after pouring the liquid crystal cell is better than that of the empty liquid crystal cell. In addition, heating the sample to a certain temperature can wipe out the external light field to write liquid crystal. The experimental results show that the optical orientation of the liquid crystal based on the polyimide orientation layer is not only controlled by the wavelength of the light, but also by the polarization direction of the light. In addition to the application value in the field of display, the research results of this paper are also suitable for the development of optical communication liquid crystal devices, such as optical power control devices and polarization controllers. It can be used as a reference for the fabrication and storage of optical information of new type orientation layer using optically controlled orientation technology.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O633.2;O753.2
【参考文献】
相关期刊论文 前7条
1 侯柳强;王森;马红梅;孙玉宝;;一种宽视角和快速响应的连续视角可控液晶显示[J];液晶与显示;2016年07期
2 王骁乾;沈冬;郑致刚;郭海成;;液晶光控取向技术进展[J];液晶与显示;2015年05期
3 王添洁;于海峰;;光响应液晶嵌段共聚物研究进展[J];液晶与显示;2015年04期
4 苏坚;陈鹤鸣;;基于液晶光子晶体的太赫兹波调制器[J];光学学报;2010年09期
5 许军;;液晶科学技术的回顾与展望[J];现代显示;2006年11期
6 陆子凤,张彦杰,吴志发,刘益春,谭昌会,赵英英;手性偶氮苯衍生物的光致变色和全息存储特性研究[J];中国激光;2005年02期
7 马颖,张方辉,盛锋,王照红;液晶显示器摩擦取向技术的新发展[J];液晶与显示;2003年04期
，本文编号：2398137
本文链接：https://www.wllwen.com/kejilunwen/huaxue/2398137.html
教材专著
