The pretilt angle of liquid crystal (LC) molecules in LC cells was manipulated by adding a mixture of two photocurable monomers, alkyl acrylate and biphenyl diacrylate, into the LCs after the UV treatment. The hexyl acrylate and octadecyl acrylate were applied to examine the alkyl chain length effect on the pretilt angle control under the condition of a fixed concentration of biphenyl diacrylate. The LC alignment was continuously adjusted from homogeneous to homeotropic alignment in the polymer-stabilized LC system by simply increasing the alkyl acrylate concentration in the LCs. At a given molar concentration of alkyl acrylate, the addition of octadecyl acrylate exhibits higher pretilt angle than that of hexyl acrylate. Both the pretilt angle of the LCs and advancing contact angle of water on the inner surfaces of LC cells simultaneously changed due to surface chemical nature and surface roughness. The pretilt angle increases along with an increase in the advancing contact angle. As a consequence, the surface advancing contact angle acts as an index for pretilt angle control.

中文翻译：

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单体烷基链长在聚合物稳定的液晶取向系统预倾角控制中的作用

通过在UV处理后，将两种光固化单体（丙烯酸烷基酯和二丙烯酸联苯酯）的混合物添加到LC中，可以控制LC单元中液晶（LC）分子的预倾角。应用丙烯酸己酯和丙烯酸十八烷基酯在固定浓度的联苯二丙烯酸酯的条件下研究烷基链长度对预倾角控制的影响。通过简单地增加LC中丙烯酸烷基酯的浓度，可以在聚合物稳定的LC系统中将LC排列从均相排列连续调整为垂直排列。在丙烯酸​​烷基酯的给定摩尔浓度下，丙烯酸十八烷基酯的添加呈现出比丙烯酸己基酯更高的预倾角。由于表面化学性质和表面粗糙度，LC的预倾斜角和水在LC单元内表面上的前进接触角同时改变。预倾角随着前进接触角的增加而增加。结果，表面前进接触角用作预倾角控制的指标。