Anisotropic surface morphology of azopolymer films generated by polarized UV light irradiation

X-ray reflectivity measurements reveal anisotropy of the vertical surface r oughness caused by exposure to linearly polarized UV (LPUV) light in the fi lms of two azopolymers. The irradiated surface is found to have higher roug hness in the direction parallel to the direction of polarization than in th e orthogonal direction. The photo-modification of the surface morphology is caused by spatial changes induced in polymer films by LPUV irradiation. Th e important role of surface roughness anisotropy in determining the alignme nt of liquid crystals is discussed.