应变液晶的负压光效应和反式压光效应

介绍聚合物分散液晶和应变液晶概念,给出聚合物分散液晶调光玻璃的"正压光效应"、"负压光效应"和"反式压光效应"三种效应定义.实验制备出负压光效应和反式压光效应新型应变调光玻璃样品,测试样品散射态雾度90%以上,半透明态透光率接近30%.用偏光显微术研究压光效应原理,表明对样品施加垂面按压或拉伸的应力诱导作用会引起液晶微滴中液晶分子具有某些特殊排列方式,导致样品光学性质发生显著变化.建立垂面拉伸液晶微滴模型,计算模拟所绘出的图形与偏光显微镜照片独特花样十分相似,进而合理解释了实验现象.应变液晶压光效应研究具有聚合物分散液晶基础研究意义和开发非电控调光玻璃的实际应用价值.

Negative piezo-optical effect and the inverse mode piezo-o ptical effect of stressed liquid crystals

The concepts of polymer dispersed liquid crystal (PDLC) and stressed liquid crystal (SLC) are introduced; the three kinds of definitions, i.e., “positive piezo-optical effect”, “negative piezo-optical effect” and “inverse mode piezo-optical effect” of PDLC switchable glass are given. The new types of stressed switchable glass samples of negative piezo-optical effect and inverse mode piezo-optical effect are prepared. The experimental results show that the haze is above 90% in a scattering state and the transmittance is nearly 30% in a translucent state. The principle of piezo-optical effect is analyzed with polarization microscopy. The results show that the vertical surface pressure or stretching stress applied to the sample will result in the special reorientation of LC molecules in LC droplets, which causes the optical characteristics of the sample to change significantly. The mode of vertical stretched liquid crystal droplet is proposed, the computation results and graph plotting conform with the results from the micrographs of polarizing microscope very well, so that the experimental phenomena are reasonably explained. The research on SLC piezo-optical effect has the fundamental significance for studying the PDLC and the application value for developing non-electro-optic switchable glass.
Keywords： stressed liquid crystals positive piezo-optical effect negative piezo-optical effect inverse mode piezo-optical effect