Photomodulated electro-optical response in self-supporting liquid crystalline physical gels
Photomodulated electro-optical response in self-supporting liquid crystalline physical gels
复制标题
自支撑液晶物理凝胶中的光调制电光响应
DOI：
10.1021/acs.langmuir.8b01031
复制
发表时间：
2018
期刊：
影响因子：
3.9
通讯作者：
Xie Xiaolin
中科院分区：
文献类型：
--
作者：
Zhao Dongxu;Ouyang Dan;Jiang Man;Liao Yonggui;Peng Haiyan;Xie Xiaolin
光响应液晶（LC）物理凝胶由于具有对光刺激有强烈响应的性质而受到越来越多的关注。尽管许多努力都集中在通过光异构化破坏和恢复物理凝胶上，但即使在光照射下也很难同时实现快速电光响应和高机械性能。本工作设计并合成了两种具有不同端基的含偶氮苯胶凝剂(AG1和AG2)。两种胶凝剂都能诱导向列型液晶 P0616A 在低含量下自组装成各向异性相分离液晶物理凝胶。系统地研究了它们的相变行为、热稳定性、微观结构和机械强度。与P0616A中的AG2相比，P0616A/AG1凝胶表现出更好的力学性能。当胶凝剂含量大于3 wt%时，P0616A/AG1凝胶具有良好的自支撑能力，储能模量大于104Pa。因此，P0616A/AG1gels 的光响应电光特性和结构受到了详细关注。令人惊讶的是，P0616A/AG1gels 的电光响应速度在紫外线照射下能够得到提升。特别是，与初始状态相比，衰减时间（τoff）仅为一半左右，而凝胶仍然表现出良好的自支撑能力； LC物理凝胶的网络在宏观和微观结构水平上也没有变化。这些令人兴奋的结果将为这种材料在电光器件中的应用打开一扇大门。
Photoresponsive liquid crystal (LC) physical gels have attracted more and more attention because of the nature of strong response via light stimulus. Although many efforts on the breaking and recovering of physical gels through photoisomerization have been focused, fast electro-optical response and high mechanical properties even upon light irradiations are difficult to achieve at the same time. In this work, two kinds of azobenzene-containing gelators (AG1andAG2) with different terminal groups were designed and synthesized. Both gelators could induce the nematic LC P0616A self-assemble into anisotropic phase-separated LC physical gels at low contents. Their phase-transition behavior, thermal stability, microstructure, and mechanical strength were systematically studied. Compared withAG2in P0616A, the P0616A/AG1gels showed better mechanical property. When the gelator content was above 3 wt %, the P0616A/AG1gels possessed good self-supporting ability with a storage modulus more than 104Pa. Thus, the photoresponsive electro-optical properties and structures of P0616A/AG1gels were focused in detail. It was surprising that the electro-optical response speed of the P0616A/AG1gels could be promoted upon UV irradiation. In particular, the decay time (τoff) was only about half when compared with the initial state, whereas the gels still exhibited good self-supporting ability; also the network of the LC physical gels had no change at macro- and microstructural levels. These exciting results would open a door for the application of this material in electro-optical devices.