Argon glow discharge and vapor-phase grafting of vinyl monomers on wettability of polyethylene

Abstract

Argon glow discharge-induced vapor-phase grafting of vinyl monomers containing various polar pendant groups onto PE films was investigated. Relationships between the enhanced wetting properties and the level of grafting, the types of pendant groups, and the surface topographical features were established. Improved wettability of the grafted PE surfaces is attributed to both the increased surface polarity and topographical features. On AA-grafted PE surfaces with optimal wettability, microcracks, with depths of 130 ∼ 250 nm, lengths over 10 μm, and widths between 1.5 and 6.0 μm, are proved to be a topographical feature necessary for improved wettability. With sufficient microcracks, grafting with vinyl monomers containing carbonyl groups, i.e., carboxyl, aldehyde, and ketone groups, improved surface wetting more than grafting with those containing either hydroxyl and epoxy groups. The acquired wettability of vinyl monomer-grafted PE surface is attributed to the physicochemical synergism between the microcracks and the polar groups.