Zhao Dongyu, Huang Wei, Cao Hui, Zheng Yudong, Wang Guojie, Yang Zhou, Yang Huai
J Phys Chem B. 2009 Mar 12;113(10):2961-5. doi: 10.1021/jp8101089.
In this paper, we report a novel organic monomer containing dual photocross-linkable groups and success in realizing photoinduced homeotropic alignment of nematic liquid crystals (LCs) with it. It was first revealed that direct irradiation of the photoalignment thin film with nonpolarized ultraviolet (UV) light at 365.0 nm brought out homeotropic orientation of the photopolymer as a result of the photocross-linking of the dual photoreactive groups. When the thin film was obliquely irradiated with nonpolarized UV light, the pretilt angles of nematic LC were generated. Interestingly, we find that the hydrophobicity of the photopolymer increases with increasing irradiation time. In discussing the mechanism of the homeotropic alignment, it was found that the incorporation of the dual photofunctional group of the photoalignment molecules as well as the extreme hydrophobicity of the photopolymer play the essential roles. This monomer cross-linked film is expected as a promising homeotropic alignment film with rubbing-free processing for the fabrication of advanced vertical alignment LC displays.
在本文中，我们报道了一种含有双光可交联基团的新型有机单体，并成功地用它实现了向列相液晶（LC）的光致垂直取向。首次发现，用365.0 nm的非偏振紫外（UV）光直接照射光取向薄膜，由于双光反应性基团的光交联作用，导致光聚合物出现垂直取向。当用非偏振紫外光倾斜照射薄膜时，向列相液晶产生了预倾角。有趣的是，我们发现光聚合物的疏水性随照射时间的增加而增加。在讨论垂直取向的机理时，发现光取向分子的双光功能基团的引入以及光聚合物的极端疏水性起着至关重要的作用。这种单体交联膜有望成为一种有前途的垂直取向膜，用于制造先进的垂直取向液晶显示器，无需摩擦处理。
