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

X-ray re ectivity measurements reveal anisotropy of the vertical surface roughness caused by exposure to linearly polarized UV (LPUV) light in the lms of two azopolymers. The irradiated surface is found to have higher roughness in the direction parallel to the direction of polarization than in the orthogonal direction. The photo-modi cation of the surface morphology is caused by spatial changes induced in polymer lms by LPUV irradiation. The important role of surface roughness anisotropy in determining the alignment of liquid crystals is discussed

Surface Dynamics in Rubbed Polymer Thin Films Probed with Optical Birefringence Measurements

Measurements of the optical birefringence were used to probe the relaxation of rubbed ultrathin polystyrene (PS) films on glass substrates. It was found that the glass transition temperature, Tg, of the films dropped by 15−20 K as the film thickness decreased from 10 μm to 5.8 nm. Experiments on thick films (10 μm) revealed that molecules closer to the polymer−air interface relax more quickly than molecules farther from the interface. These results are explained in the context of past experimental studies of thermal properties of similar ultrathin polymer films