Surface graft copolymerization induced adhesion of polyaniline film to polytetrafluoroethylene film and copper foil

Adhesion of emeraldine base (EB) films of polyaniline (PANI) to plasma-pretreated polytetrafluoroethylene (PTFE) films and to copper foils were achieved via thermally induced surface graft copolymerization with concurrent lamination. The process was carried out under atmospheric conditions in the presence of pure and aqueous solutions of 1-vinyl imidazole (VIDz) or acrylic acid (AAc) and in the absence of an added polymerization initiator. The chemical composition and microstructure of the graft copolymerized surfaces from the self-delaminated junction in water and from the mechanically delaminated interfaces were investigated by X-ray photoelectron spectroscopy (XPS). The effects of monomer concentration and thermal grafting/lamination temperature on the observed lamination strength were studied for both the EB/PTFE and EB/Cu interfaces. The lap shear adhesion strength of the EB/PTFE junction also depended on the plasma pretreatment time of the PTFE surface. Maximum lap shear adhesion strength approaching 200 N/cm2 was obtained for the EB/PTFE interface laminated at 140°C for 1h in the presence of pure AAc monomer and with 40s of Ar plasma pretreatment time for the PTFE surface. A maximum lap shear adhesion strength of about 640 N/cm2 could be readily achieved for the EB/Cu interface for grafting/lamination carried out in the presence of 25vol% aqueous VIDz solution at 130°C.