Novel Method to Control Liquid Crystal Orientation based on Water Flow-induced Molecular Alignment

基于水流诱导分子排列控制液晶取向的新方法

基本信息

批准号：
12555267
负责人：
KIKUCHI Hirotsugu
金额：
$ 2.82万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

The uniform alignment of liquid crystal (LC) molecules is generally produced by a surface-induced alignment technique of a polymer surface. However, the conventional rubbing technique involves a serious problem that an electrostatic charge and dust are generated during mechanical friction by rubbing. In this study, a novel liquid crystal alignment technique was investigated in order to realize electrostatic charge-and dust-free on the polyimide surface. A uniform alignment of LC was obtained by using the polyimide surface which was exposed to unidirectionally flowing water at 343 K before imidization by thermal cure.The surface-induced alignment effect was not sufficient in the case of exposing the polyimide surface to the water flow after the thermal imidization. The local chain orientation on the polyimide precursor surface induced by exposing to the water flow and its amplification of the chain orientation by the thermal imidization is a possible mechanism of "water flow rubbing".Interface enhanced sum-frequency generation (ISFG) method is a second-order nonlinear optical technique, which is a powerful tool to study the surface and the interface. The ISEG method was used for investigating 4-cyano-4'-pentylbiphenyl (5CB) behavior at the (polymer / 5CB) interface. Poly (vinyl cinnamate) and poly (vinyl alcohol) were used as polymer. In both ISEG spectra, the absorbance bands attributed to the CN-stretching bands of 5CB were observed. At the (PVCi /5GB) interface, the absorbance band of CN-stretching appeared at 2225 cm^<-1>, which was in good agreement with CN-stretching band in the ET-IR spectrum of 5CB in the bulk state. However, at the (PVA/ 5CB) interface, the band of CN-stretching was sifted 100 cm^<-1> to lower frequency. This results indicate that the intermolecular interaction between PVA and 5CB is much larger than the case of PVCi and 5GB.

液晶（LC）分子的均匀排列通常是通过聚合物表面的表面诱导排列技术产生的。然而，传统的摩擦技术存在严重的问题，即在摩擦的机械摩擦过程中产生静电荷和灰尘。在这项研究中，研究了一种新颖的液晶取向技术，以实现聚酰亚胺表面的静电荷和无尘。通过热固化酰亚胺化前将聚酰亚胺表面暴露于343 K单向流动的水中，获得了均匀的液晶取向。在热固化后将聚酰亚胺表面暴露于水流中，表面诱导取向效果不充分。热酰亚胺化。暴露于水流中引起的聚酰亚胺前体表面上的局部链取向及其通过热酰亚胺化对链取向的放大是“水流摩擦”的可能机制。界面增强和频发生（ISFG）方法是一种二阶非线性光学技术，是研究表面和界面的有力工具。 ISEG 方法用于研究 4-氰基-4'-戊基联苯 (5CB) 在（聚合物/5CB）界面处的行为。使用聚(肉桂酸乙烯酯)和聚(乙烯醇)作为聚合物。在两个 ISEG 光谱中，均观察到归因于 5CB CN 拉伸带的吸收带。在(PVCi/5GB)界面处，CN拉伸的吸收带出现在2225cm^-1处，这与本体状态的5CB的ET-IR光谱中的CN拉伸吸收带非常吻合。然而，在(PVA/5CB)界面处，CN拉伸的频带被筛分100cm ^ -1 至较低频率。该结果表明PVA和5CB之间的分子间相互作用比PVCi和5GB的情况大得多。