PLASMA MODIFICATION OF POLYMETHYLMETHACRYLATE AND POLYETHYLENETEREPHTHALATE SURFACES

Noble gas (HeArXe) and reactive gas (O2,N2) plasma treatments of polym ethylmethacrylate (PMMA) and polyethyleneterephthalate (PET) surfaces were performed in an electron-cyclotron-resonance plasma. In situ surf ace analysis by x-ray photoelectron spectroscopy reveals well-defined surface compositions. From these measurements it is concluded that, in dependently of the plasma gas, the plasma ions easily decompose the es ter group in PMMA in its constituents by an ion-electron recombination process, while in PET the ester decomposition is less pronounced. The difference is ascribed to the presence in PET of a phenyl ring, which protects the ester group by various mechanisms. The study of O2 Plasm a treatments shows that the equilibrium between the depletion of oxyge n and the incorporation of the reactive species in the polymer surface is solely determined by the ion current. The plasma-polymer interacti ons are qualitatively explained by simple rules of intermolecular forc es and ion-electron recombination phenomena.