共查询到19条相似文献,搜索用时 531 毫秒
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红外二向色性法测量取向膜表面液晶界面层的取向度 总被引:2,自引:2,他引:0
液晶分子的取向排列通常需取向膜诱导引发,但实验发现强摩擦处理的取向膜表面的液晶分子有序度远低于液晶体内部的有序度,大约为体内部的1/2。实验中采用楔形液晶盒,用较严谨的红外二向色性吸收定量分析了液晶层厚方向上的平均有序度随液晶层厚的变化,并通过这一结果的理论拟合,获得了取向膜表面的液晶分子取向有序度,同时获得了液晶界面层厚大约为7nm。这些结果说明液晶具有抵制外界微扰、自我修复分子取向度的能力,有利于对液晶排列机理的理解,也为研究新的取向方法提供了参照依据。 相似文献
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聚酰亚胺液晶垂直取向膜的表面取向分析 总被引:3,自引:3,他引:0
采用均苯四甲酸二酐(PMDA)、4,4′-二胺基二苯甲烷(MDA)以及侧基含联苯和己基的二胺(TBCA)三元共聚制备了聚酰亚胺垂直取向剂,摩擦前后得到相同的垂直取向效果,探讨了侧链二胺TBCA的含量对聚酰亚胺取向膜垂直取向性能的影响,采用衰减全反射红外光谱(ATR-FTIR)对摩擦前后聚酰亚胺膜表面侧链的相对含量进行了对比,并运用原子力显微镜(AFM)考察了表面细微沟纹对液晶分子取向的影响。结果表明,在取向膜未经摩擦没有产生表面沟纹的情况下液晶分子也能取向,并且这类取向膜表面侧链的含量与摩擦后的含量相当。 相似文献
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液晶分子取向技术研究 总被引:1,自引:1,他引:0
综述目前液晶显示器(LCD)工业生产中广泛使用的液晶分子取向技术。主要讨论摩擦技术、非摩擦技术和PI取向膜的性能。对这些技术的发展状况、特点与局限性以及今后的发展趋势进行了较为详尽的论述。 相似文献
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椭圆偏光解析法对液晶界面层分子有序度的研究 总被引:6,自引:2,他引:4
论述了向列相液晶分子取向有序度的评价方法以及与宏观物理张量之间的关系, 阐述了椭圆偏光解析法测量分子取向有序度的原理,并应用在基板表面液晶界面层中的测量。实验结果表明, 即使是在强摩擦条件下基板表面附近 50nm 厚的液晶层中,分子取向有序度低于液晶体内部的值。讨论了实验误差, 确认了这一结果的合理性, 为澄清液晶取向排列原动力模型提供了实验依据。 相似文献
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在具有高驱动电压的液晶显示器中,为了对液晶器件起到保护作用,以采用增加取向层厚度的方法来解决某些显示器件由于驱动电压过高导致的问题。当取向层厚度不可忽略时,随着取向层厚度增加会导致器件驱动电压升高。本文利用扭曲向列相液晶显示器结构,通过模拟和实验分析了取向层厚度对LCD的影响以及不同介电常数的取向层对LCD的影响。结果表明:当取向层的介电常数大于20时,能够有效降低TN-LCD驱动电压。当其介电常数大于500时,其厚度变化对驱动电压的影响变得很小。本文结果对降低高驱动电压液晶器件的驱动电压有重要的指导性意义。 相似文献
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用偏光显微镜解析界面层分子有序度 总被引:4,自引:4,他引:0
阐述了用偏光显微镜测量液晶盒中分子有序度分布的方法。采用楔形液盒获得了仅有十几个nm的界面层信息,并提出具有创意性的偏光解析方法。通过这一工作得出以下结论:在高分子膜表面通过摩擦过程获得的液晶取向排列,其界面子有序度为体内部序度的60%以下,有序度远低于体内部;由于固体界面对液晶排列的影响,产生一个有序度连续变化的界面层,其厚度大约于体内部;由于固体界面对液晶排列的影响,产生一个有序度连续变化的界 相似文献
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STN-LCD制造摩擦工艺及静电消除工艺探讨 总被引:1,自引:1,他引:0
定向层(PI层)是STN-LCD合铁一个重要组成部分。因为简单地把液晶夹在两片玻璃基板之间,很难获得均匀的液晶分子排列,只有在基板作上定向层并作摩擦处理后,液晶的物性常数因分子排列状态才会发生变化,液晶分子对于电场等外力的响应也会变得有序。所以,研究液晶分子的排列定向技术,在液晶显示元件构成技术上具有重要意义。 相似文献
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在经摩擦处理的聚合物取向层上,液晶分子是在离表面倾斜的某一极角上取向排列起来的。这一预倾角在设计LCD时是一个重要参数。本文介绍了聚合物取向层的摩擦工艺,并介绍了测定在取向层中聚合物倾斜角的测量方法。本文还描述了在聚合物倾斜方向和液晶层预倾角之间的关系。 相似文献
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Won‐Kyu Lee Yeon Sik Choi Young‐Gu Kang Jinwoo Sung Dae‐Shik Seo Cheolmin Park 《Advanced functional materials》2011,21(20):3843-3850
We have developed a high performance liquid crystal (LC) alignment layer of ultra‐thin single wall carbon nanotubes (SWNTs) and a conjugated block copolymer nanocomposite that is solution‐processible for conventional twisted nematic (TN) LC cells. The alignment layer is based on the non‐destructive solution dispersion of nanotubes with a poly(styrene‐b‐ paraphenylene) (PS‐b‐PPP) copolymer and subsequent spin coating, followed by conventional rubbing without a post‐annealing process. Topographically grooved nanocomposite films with two dimensionally (2D) networked SWNTs embedded in a block copolymer matrix were created using a rubbing process in which bundles of SWNTs on the composite surface were effectively removed. The LCs were well aligned with a stable pre‐tilt angle of approximately 2° on our extremely transparent nanocomposite, which gave rise to superfast switching of the TN LC molecules that was approximately 3.8 ms, or four times faster than that on a commercial polyimide layer. Furthermore, the TN LCD cells containing our SWNT nanocomposite alignment layers exhibited low power operation at an effective switching voltage amplitude of approximately 1.3 V without capacitance hysteresis. 相似文献
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In this paper we describe methods to control liquid crystal (LC) alignment using plasma discharge on ferroelectric fluoropolymers. Two different plasma modification techniques were investigated: corona discharge and RF plasma in Ar gas. Corona discharge is a proven technique known to reorient the dipoles in poly (vinylidene fluoride) and its copolymers resulting in a strong remnant polarization. The polarization was patterned resulting in preferential LC alignment in selected regions. RF plasma in Ar gas defluorinates the polymer surface leading to planar alignment of positive dielectric anisotropy LCs. The defluorination of the alignment layer also causes low voltage switching of the LC. 相似文献
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为了制备具有自取向功能的聚酰亚胺(PI)取向膜,避免摩擦工序在取向膜表面造成静电、灰尘、配向不良等不利影响,本实验通过一系列黏度不同且有水平及垂直取向功能的PI溶液,研究了PI液黏度和其取向膜表面粗糙度的关系,进而研究了PI膜表面粗糙度和液晶预倾角(θ_p)的关系。研究发现:取向膜表面粗糙度随着PI液黏度的增大而增大,θ_p随着粗糙度的增大而增大,但当粗糙度大于一定值(3.760nm)后,θ_p增长缓慢并趋于稳定。这主要是因为PI液黏度增大时,阻碍了相邻PI液滴通过分子链段协同运动向彼此扩散的几率,进而形成取向膜表面的"峰谷"形貌,这种"峰谷"形貌表面对液晶垂直取向起到了支撑作用,正是这种支撑作用使得液晶分子获得较大的θ_p。结合液晶面板响应时间对高预倾角的要求和Inkjet PI液滴喷嘴过小对PI液黏度的限制,得出PI液黏度大约为41CP时,此时取向膜表面粗糙度为4.830nm,液晶取向角为5.5°,能较好地满足液晶取向的要求。 相似文献
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H. M. Song J. C. Kim J. H. Hong Y. B. Lee J. Choi J. I. Lee W. S. Kim J.‐H. Kim N. H. Hur 《Advanced functional materials》2007,17(13):2070-2076
The fabrication of transparent, flexible, and optically homogeneous magnetic composites containing ferrite (Fe3O4) nanoparticles, liquid crystals (LCs), and siloxane backbones is reported. The transparent magnets are achieved by covalently bonding LCs to the siloxane backbones and then linking them to dopamine‐functionalized ferrite nanocrystals. They exhibit simultaneous high transparency and strong magnetic properties. A remarkable feature of these films is that the surface morphology of the LC‐attached ferrite films can be tuned by an external magnetic field, demonstrating a striped surface in the direction of the field. We show that the LC‐attached film can act as an alignment layer to orient LCs, enabling the development of LC alignment surfaces on the basis of these nanomagnet–LC polymer composites. 相似文献
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D. Sainova A. Zen H.‐G. Nothofer U. Asawapirom U. Scherf R. Hagen T. Bieringer S. Kostromine D. Neher 《Advanced functional materials》2002,12(1):49-57
Liquid‐crystalline (LC) polyfluorenes have been successfully aligned on photoaddressable polymers (PAPs). This is the first example of the alignment of a LC main chain polymer on a photoaligned layer. The degree of molecular alignment in the fluorescent polyfluorene layer on top of an ultra‐thin PAP layer is shown to depend strongly on the chemical nature of the PAP. Good alignment with dichroic ratios of more than 10 was only achieved with PAPs containing liquid‐crystalline side chains. Patterning with laterally structured alignment was realized in several ways, utilizing reorientation with orthogonally polarized light. Thin PAP layers have further been utilized as hole‐conducting alignment layers in polymer light‐emitting diodes (LEDs) with polarized emission. In order to facilitate hole transport through the alignment layer, different concentrations of a hole‐transporting molecule (HTM) have been mixed into the PAP layer. These hole‐conducting alignment layers retained their aligning abilities even at HTM concentrations of 20 wt.‐%. LEDs with photometric polarization ratios in emission of up to 14 at a brightness of up to 200 cd/m2 and an efficiency of 0.3 cd/A could be realized. 相似文献