Analysis of Rubbed Polyimide Films by Polarized Infrared Spectroscopy

Polarized infrared spectroscopy was applied to the analysis of rubbed polyimide films. N2 purge of a sample chamber and increased substrate thickness enhanced the detection sensitivity. Dichroic differences were measured for the rubbed polyimide films at varied translating speed of the rubbing roller and at varied substrate temperature. The results suggest that the orientation of the polyimide was enhanced by increased polyimide surface temperature brought about by the heat of friction or the external heat. Moreover, a correlation between the LC alignment and the orientation of the polyimide chains was revealed by the analysis of the dichroic difference of the rubbed polyimide films immersed in organic solvents and the LC alignment on the films.