Preparation of Resposive Poymer Surfaces to Environmental Changes

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Poly(tetrafluoroethylene) (PTFE) and poly(p-phenylene terephthalamide) (PPTA) were modified by graft copolymerization using sodium vinylsulfonate (SVS) and glycidyl methacrylate (GMA) as monomers to form responsive surface to environmental changes. Peroxides were formed on PTFE and PPTA surfaces by argon plasma exposure, and the graft copolymerization of SVS or GMA was carried out from the peroxides on the PTFE and PPTA surfaces. The chemical composition of the grafted PTFE and PPTA surfaces was analyzed with XPS.The coverage with the SVS graft polymers on the PTFE surface was estimated to be 43 % from the XPS spectra, and the coverage with the GMA graft polymers on the PPTA surface was 31 - 49 %. The grafted PTFE surface was somewhat hydrophilic, but the hydrophilicity was lower than the plasma-treated PTFE.The contact angle of water against the grafted PTFE decreased from 111 degrees to 84 degrees. The low hydrophilicity of the grafted PTFE surface may be due to incomplete coverage with the SVS graft polymers. The graft copolymerization with GMA improved adhesion between PPTA and epoxy adhesive. The 90 peel strength was increased 2.7 times by the graft polymerization. The failure from the PPTA/epoxy adhesive joints occurred in the epoxy adhesive layer rather than at the interface between the PPTA and the epoxy adhesive layer.