Anchoring of a liquid crystal on a photoaligning layer with varying surface morphology

We report the studies of the photoalignment properties of fluorinated polyv inylcinnamate (PVCN-F) films. The influence of film preparation and UV ligh t irradiation conditions on anchoring properties were investigated. We have studied surface director reorientation in a magnetic field for various exp osures and surface conditions. The results obtained show that both the prep aration conditions and exposure time determine surface morphology, which in turn affect the value of anchoring energy. For small concentration of the PVCN-F in a spin-coated solution the surface of the aligning film is rather smooth, and the value of anchoring energy W-phi = 10(-5) J m(-2) is presum ably determined by a physico-chemical interaction. Higher concentration of the PVCN-F results in rough irregularities on the surface, and the value of the anchoring value increases due to a predominant contribution of the Ber reman-type anchoring up to 7 x 10(-5) J m(-2).