Surface analysis of plasma-deposited polymer films, 1 - ToF-SSIMS of plasma polystyrene before and after exposure to ambient air

Pulsed plasma-deposited polystyrene films were studied by time-of-flight static secondary ion mass spectrometry (ToF-SSIMS) before and after exposure to ambient air. The influence of the external plasma parameters on the secondary ion mass spectra of plasma-deposited polystyrene films was investigated. From these data, information on the chemical character of the plasma polystyrene films was derived. In the range of deposition conditions applied in this study, the fragmentation of styrene is a minor process. The main process is probably the radical chain propagation to polymers. All the polystyrene plasma polymers, relying on ToF-SIMS, seem to be rather similar to a reference polystyrene oligomer sample. When the plasma polymers are exposed to air, extensive oxygen incorporation occurs. Oxygen uptake was found to alter the emission probabilities of secondary ions. A relation between the regularity of the plasma polymers and the amount of oxygen incorporation was found. The result was that the chemical regularity of the plasma polystyrene decreases when the effective power in the plasma is increased.