SURFACE RELAXATIONS IN POLYMERS

Near-edge X-ray absorption line structure, NEXAFS, spectroscopy was us ed to investigate the relaxations of polystyrene, a typical amorphous polymer, near a free surface after the imposition of a small deformati on. Using synchrotron radiation, the NEXAFS dichroic ratio was determi ned for both the Auger and total electron yield processes as a functio n of temperature to determine the orientation of the polymer in the fi rst 1 and 10 nm from the free surface, respectively. Complete relaxati on of the polymer was not seen for temperatures less than the bulk gla ss transition temperature. No evidence of enhanced mobility at the fre e surface was found. A planar relaxation of the polymer was found in, the first nanometer from the free surface, whereas in the first 10 nm, the dominant relaxation was normal to the surface.