Study of the degradation of plasma-oxidized polystyrene by time- and angle-resolved x-ray photoelectron spectroscopy

Angle-resolved x-ray photoelectron spectroscopy (ARXPS) measurements were made, in repeated sequences employing Al and Mg x-ray sources alternately, on a polystyrene sample that had been exposed to an oxygen plasma. It was observed that oxygen was lost from the sample over a period of 5 h and 40 min. The ARXPS data sets were corrected for the time displacement between consecutive measurements at different photoemission angles and fitted with three simple models in order to extract oxygen concentration-depth profiles, consistent with the data, as a function of time. The oxygen depth profiles were found to evolve in a consistent manner, indicating both a loss of average oxygen content and thickness in the 'oxidized polymer layer'. Copyright (C) 2003 John Wiley Sons, Ltd.