Photoinduced orientational transitions in a thermotropic nematic liquid crystal caused by modulation of the boundary conditions at the water surface were observed and investigated. The initially degenerated planar anchoring of liquid crystal at the water surface becomes homeotropic under near-UV irradiation which induces photoizomerization of comb-shaped azobenzene polymer additives adsorbed from the liquid crystal to its interface with water. After irradiation, the photoinduced orientational structures spontaneously relax to the initial ones. It was shown that the orientational sensitivity to light irradiation strongly depends on the polymerization degree of azobenzene additives.

中文翻译：

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偶氮苯聚合物添加剂在热致向列型液晶和水之间的界面上的光取向

观察和研究了水相边界条件的调节引起的热致向列型液晶中的光诱导取向转变。在近紫外线照射下，液晶在水表面的最初退化的平面锚固变为垂直，这引起从液晶吸收到与水的界面的梳形偶氮苯聚合物添加剂的光致异构化。辐照后，光诱导的定向结构自发地松弛到初始结构。结果表明，对光辐射的取向敏感性强烈取决于偶氮苯添加剂的聚合度。