红外二向色性法测量取向膜表面液晶界面层的取向度

Using Infrared Dichroism to Study Orientational Order of Liquid Crystals on the Alignment Layer Surface

液晶分子的取向排列通常需取向膜诱导引发,但实验发现强摩擦处理的取向膜表面的液晶分子有序度远低于液晶体内部的有序度,大约为体内部的1/2。实验中采用楔形液晶盒,用较严谨的红外二向色性吸收定量分析了液晶层厚方向上的平均有序度随液晶层厚的变化,并通过这一结果的理论拟合,获得了取向膜表面的液晶分子取向有序度,同时获得了液晶界面层厚大约为7nm。这些结果说明液晶具有抵制外界微扰、自我修复分子取向度的能力,有助于对液晶排列机理的理解,也为研究新的取向方法提供了参照依据。

Liquid crystal (LC) alignment is the most importance in the LC devices. In this paper, using infrared dichroism, the researchers quantitatively analyzed the LC scalar order parameters on the surface of an alignment layer after rubbing treatment. The careful measurement of dichroic infrared absorbance was fulfilled. The result gives the evidence that the LC order parameter on the surface of the alignment layer is about 1/2 of that in the LC bulk, and the thickness of a LC interface layer is about 7nm. These results imply that liquid crystals have selfrepairing capability on its molecular orientation order. It is helpful to understand the alignment mechanism of liquid crystals as well as can be an experimental reference for nonrubbing alignment treatments.