通过紫外引发相分散法制备了一种新型反式聚合物稳定液晶(PSLC)光电薄膜--平行反式PSLC,并提出其反式变色机理.此薄膜无需垂直取向剂,仅使用普通向列液晶5CB和合成的可聚合丙烯酸单体4'-(4-氰基苯基)苯氧基丁基一甲基丙烯酸酯(CPMA),紫外固化一定时间即可制得.在偏振光照射下其透光率随电压增加而降低,实现了光电薄膜的反式变色效果.通过偏光显微镜照片看出,单体CPMA中的极性棒状基团可以在固化过程中与液晶共同在取向层作用下取向,而不会破坏液晶分子的排列,使体系具有均一的折射率.因此尽管聚CPMA、聚丙烯腈和聚甲基丙烯酸甲酯折射率接近,但使用CPMA得到的反式薄膜的透光率(82.3%)比后两者(23.3%和18.9%)高得多.当向CPMA薄膜施加电场后,CPMA薄膜中部分液晶在聚合物网络限制下不能沿电场取向,它们与不受网络影响而沿电场取向的液晶形成折射率差异,薄膜呈不透明态,实现了光电薄膜的反式效果.当液晶与单体质量比为6:1时,反式薄膜的光电性能最好,阈值电压低于2.3 V·μm-1.
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