Analysis of the alignment order parameter of liquid crystal at the rubbed polymer surface

Abstract

The alignment mechanism on the rubbed polymer films has not yet been clearly explained although it is widely used in practice. In this work, we investigate the order parameter of liquid crystal on the surfaces of the rubbed polyimide films by measuring the anisotropy of infrared absorbance using a FT-IR method as a function of a cell thickness. From the results, we clarified that the order parameter of the liquid crystal decreases with approaching to the surface. In addition, the order parameter at the surface was found to be surprisingly low even if the surface is rubbed strongly.