Abstract
Surface specific sum-frequency vibrational spectroscopy (SFVS) and second-harmonic generation (SHG) were used to study the structures of polymer surfaces modified by linearly polarized UV irradiation or mechanical rubbing. The spectroscopic results show that the surface anisotropy of a polyimide surface resulting from bond breaking by linearly polarized UV irradiation is extremely small compared to a rubbed surface. On a rubbed polystyrene surface, the phenyl sidegroups are well aligned by rubbing in the direction perpendicular to rubbing but tilt from the surface normal with a broad distribution.