Mechanisms of liquid crystal alignment on buffed polyimide surfaces

Abstract

The surfaces of cured polyimide films, subjected to different buffing and cure profiles, have been examined by atomic force microscopy (AFM). The magnitude of a local stress applied to a polymer surface during buffing was estimated by imaging the surface tracks of buffing polymer fibers. Combining these experiments with a study of alignment characteristics of liquid crystals shows that the liquid crystal alignment is mainly caused by the oriented polymer chains which are formed most likely by the plastic deformation under the buffing stress