COMPARATIVE IN-SITU TOF-SIMS XPS STUDY OF POLYSTYRENE MODIFIED BY ARGON, OXYGEN AND NITROGEN PLASMAS/

The on-line combination of time-of-flight secondary ion mass spectrome try (ToF-SIMS) and monochromatized photoelectron spectroscopy is a val uable analytical tool for the characterization of chemically modified surfaces. By an in situ combination of these techniques with a plasma modification chamber, we have investigated polystyrene surfaces modifi ed by various kinds of microwave plasmas (argon, oxygen and nitrogen). The modified surfaces are widely different with respect to the incorp oration of elements originating from the plasma, the degree of chemica l changes caused by the plasma and the plasma-induced etching rate. Si gnificant formation of new functional groups specific for the plasma g as is only observed for nitrogen and oxygen. As compared to nitrogen a nd argon, treatment with the oxygen plasma leads to a high etching rat e, but only moderate changes of the chemical state of the polymer surf ace. In all cases, severe degradation of the aromatic system occurs. E xposure to air after plasma treatment leads to the uptake of considera ble amounts of oxygen. In the case of the oxygen and argon plasma, the high mass resolution of ToF-SIMS allows the identification and distin ction of clusters that are specific for the oxygen incorporated during plasma treatment and those appearing during exposure to the atmospher e.