Surface Effects on Photo-Alignment of Polyimide Blends Containing Cinnamoyl Moiety

Abstract

Polyimide containing cinnamate moiety has a good potential ability as a photo-alignment material. However, the application of photo-alignment to manufacturing LCDs is still limited due to hard to generate of pretilt angle. In order to generate large pretilt angles, some technologies are introduced. One technology is to change the ratio of the imidization and another technique is to use homeotropic alignment material. We prepared polyimide (PI) blends with fluorinated PI to control pretilt angle. Atomic force microscopy images showed surface morphology change by addition of fluorinated PI with increasing alignment angle. Photoreactive cinnamate moiety was introduced by interfacial reaction and photochemical reactivity was confirmed by contact angle and pretilt measurement. The pretilt angle of the LC cells was about 7.2 degrees.