Surface modification of poly(vinylidene fluoride) films by graft copolymerization for adhesion improvement with evaporated metals

Abstract

Surface modification of Ar plasma pretreated poly(vinylidene fluoride) (PVDF) films via UV-induced graft copolymerization with glycidyl methacrylate (GMA) and 1-vinyl imidazole (VIDz) was carried out to improve the adhesion with evaporated metals, such as aluminum and copper. The surface compositions of the graft copolymerized PVDF films were determined by X-ray photoelectron spectroscopy (XPS). The adhesion strengths were affected by the type of monomer used for graft copolymerization, the plasma pretreatment time of the PVDF film, the UV graft copolymerization time, and the interaction between the metal and the grafted polymer. T-peel adhesion strengths in excess of 8 and 10 N/cm were obtained, respectively, for the Cu/graft-modified PVDF and Al/graft-modified PVDF laminates. The failure mode for the laminates was found to be strongstrongly dependent on the adhesion strength. The strong adhesion between the metal (Cu or Al) and the surface modified PVDF film arises from the strong interaction between the functional moiety of the grafted chain and the evaporated metal atom, as well as the fact that the graft chains are covalently tethered on the PVDF film surface as a result of the surface graft copolymerization process.