P‐64: UV‐Light‐Modified Polyimide Films for Liquid‐Crystal Alignment

Abstract

Infrared, UV‐visible and X‐ray photoelectron spectroscopy measurements indicate that bond‐breaking and oxidation occur during broadband UV‐illumination of the polyimide film in the air. Surface tension and polarity are increased based on the measurements of contact angles. No obvious morphology change has been observed through atomic force microscopy analysis. While the polarized UV‐light generates a relatively small pretilt angle on a nonrubbed surface, it reduces the pretilt angle to some degree on a rubbed surface, depending upon the UV‐light polarization direction relative to the rubbing direction.