Etching and Deposition Mechanism of an Alcohol Plasma on Polycarbonate and Poly(Methyl Methacrylate): An Adhesion Promotion Mechanism for Plasma Deposited a:SiOxCyHz Coating

Favourable properties of polycarbonate have led to it replacing glass in many applications; however it does require a protective coating. Plasma deposited protective coatings of amorphous SiOxCyHz have, however, shown marginal adhesion to polycarbonate. This study has shown that plasma pre-treatments using vapours from the alcohol family improved the coating adhesion on two types of polycarbonate. It is suggested that these plasmas both etch the polycarbonate and deposit a thin plasma polymer layer. It was previously reported that a similar adhesion improvement was obtained on PMMA, however under shorter treatment times. The variation has been linked to the difference in etch rates of the two polymers. This has led to an improved understanding of the etching mechanism of both polymers when exposed to radicals.