基于聚酰亞胺的液晶光控取向研究
發(fā)布時(shí)間：2019-01-01 21:43
【摘要】：隨著液晶材料在顯示領(lǐng)域的廣泛應(yīng)用,摩擦法作為目前常用的制備液晶定向?qū)拥姆椒?由于其存在的嚴(yán)重缺點(diǎn),目前已越來(lái)越不適用,探索一種新的液晶取向技術(shù)以取代摩擦取向技術(shù)是未來(lái)液晶顯示技術(shù)的發(fā)展需要。光控取向技術(shù)以其設(shè)備簡(jiǎn)單、可以對(duì)液晶分子取向進(jìn)行微觀控制等優(yōu)點(diǎn)成為目前為止最有希望取代摩擦取向技術(shù)的非接觸性取向技術(shù)。本文采用365nm紫外光曝光、線偏振457nm激光垂直照射及兩束正交圓偏振光干涉等實(shí)驗(yàn)手段,用含偶氮基團(tuán)的聚酰亞胺聚合物制備取向?qū)?以涂有取向?qū)拥牟ＡЩ�、用兩基板組成的空液晶盒及灌有E7液晶的液晶盒為實(shí)驗(yàn)對(duì)象,通過(guò)帶有正交偏振片的CCD裝置觀察外光場(chǎng)對(duì)樣品取向的改變,通過(guò)觀察到的實(shí)驗(yàn)現(xiàn)象分析總結(jié)基于聚酰亞胺取向?qū)拥囊壕Ч饪厝∠蛱匦�。�?shí)驗(yàn)發(fā)現(xiàn),紫外光的照射會(huì)使偶氮基團(tuán)發(fā)生順?lè)串悩?gòu)反應(yīng),吸收光能變?yōu)轫樖浇Y(jié)構(gòu),使得聚合物分子轉(zhuǎn)動(dòng),垂直于基板表面重新取向,液晶分子由于其與聚合物分子之間的相互作用也會(huì)順著聚合物分子長(zhǎng)軸重新取向。用線偏振457nm激光照射液晶盒時(shí),偶氮基團(tuán)吸收光能打破平衡狀態(tài),發(fā)生順?lè)串悩?gòu)反應(yīng),變?yōu)榉词浇Y(jié)構(gòu)且往垂直于偏振光偏振方向的方向轉(zhuǎn)動(dòng),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,由于與聚合物分子之間的相互作用,液晶分子也將也液晶盒表面排列,且液晶指向矢與線偏振光偏振方向垂直。同時(shí)實(shí)驗(yàn)還發(fā)現(xiàn),有液晶的樣品其取向程度要比沒(méi)有液晶時(shí)好等多,所觀察到的圖像明暗對(duì)比度沒(méi)有液晶是大很多,并且光控取向響應(yīng)時(shí)間也比沒(méi)有液晶時(shí)短近十倍。最后還用兩束正交的圓偏振457nm激光在空液晶盒和灌有液晶的液晶盒表面干涉,成功制備出了全息偏振光柵,用632nm激光探測(cè)發(fā)現(xiàn)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,表明雖然空液晶盒也可以制備全息光柵,但灌入液晶后制備的光柵效果更好。此外,將樣品加熱到一定溫度可以擦出外光場(chǎng)對(duì)液晶的寫(xiě)入。以上實(shí)驗(yàn)結(jié)果說(shuō)明基于該聚酰亞胺取向?qū)拥囊壕Ч饪厝∠虿粌H受光的波長(zhǎng)控制,還受光的偏振方向控制。本論文的研究成果除了在顯示領(lǐng)域具有一定應(yīng)用價(jià)值,也同樣適用于光通信液晶器件的開(kāi)發(fā),如光功率控制器件及偏振控制器件等;并且對(duì)于光控取向技術(shù)應(yīng)用于新型取向?qū)拥闹苽浼肮庑畔⒋鎯?chǔ)具有一定的參考作用。
[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.
【學(xué)位授予單位】：廣東工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：O633.2;O753.2
本文編號(hào)：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.
【學(xué)位授予單位】：廣東工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：O633.2;O753.2
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