Hydroxyl Radical Etching Improves Adhesion of Plasma‐Deposited a‐SiOxCyHz Films on Poly(Methylmethacrylate)

Abstract Plasma‐deposited thin films comprising a‐SiOxCyHz with some organic content are of considerable interest as protective coatings. Their application has, however, been hampered by marginal adhesion and durability on some substrates. This study found that optimal adhesion was achieved with plasma pre‐treatments utilising vapours from the alcohol family. Our data show that rapid initial etching of the substrate occurs, probably by action of hydroxyl radicals, followed by deposition of a layer some 10 nm thick which appears to provide a surface capable of strong interfacial bonding with a subsequently deposited a‐SiOxCyHz layer. Compared with non‐depositing plasma pre‐treatments, such dual action provides stronger adhesion on PMMA. This opens up new possibilities for applying protective hard coatings on PMMA. magnified image