抄録
Liquid crystal molecules on a rubbed polymer alignment layer are oriented at some polar angle away from the surface. This so-called pretilt angle is an important parameter determining the electro-optical properties of liquid crystal devices. The generation and stability of the pretilt angle should therefore be studied. Several researchers have been studying this problem but its physical mechanism is not thoroughly understood. We investigated the polymer alignment and polymer inclination angle of surface polymer, and the change in the Liquid Crystal (LC) pretilt angle caused by heat treatment. Then we studied the change in pretilt by heat treatment of various LC materials. We concluded that the generation of LC pretilt mainly depends on the average inclination angle of the surface polymer of the alignment layer. We also consider that the LC pretilt changes after heat treatment depend on solvent effect of LC materials because the stronger the polarity of the LC is, the larger the change in LC pretilt becomes. It is suggested that temperature of heat treatment of LC cell must be carefully controlled considering the change of uniform alignment as well as LC pretilt.
