X-RAY PHOTOELECTRON-SPECTROSCOPY (XPS) AND TIME-OF-FLIGHT SECONDARY-ION MASS-SPECTROMETRY (TOF-SIMS) ANALYSIS OF UV-EXPOSED POLYSTYRENE

The surface photochemistry of polystyrene is shown to exhibit features that distinguish it from the bulk and from the polymer in solution. W e report on the use of medium- and high-resolution time-of-flight seco ndary ion mass spectrometry and X-ray photoelectron spectroscopy in an investigation of the changes that occur as a result of exposure to UV light from a 'black lamp' source. The experiment mimics closely the e ffects of natural sunlight. It is shown that there are substantial cha nges occurring in the surface molecular structure of polystyrene on ir radiation, which correspond to loss of aromaticity, and that these cha nges precede any uptake of oxygen.