Consecutive graft copolymerization of glycidyl methacrylate and aniline on poly(tetrafluoroethylene) films

Abstract

Chemical modification of Ar plasma-pretreated poly(tetrafluoroethylene) (PTFE) by film UV-induced graft copolymerization with glycidyl methacrylate (GMA), followed by oxidative graft copolymerization of aniline and reactive immobilization of polyaniline (PANI) chains have been carried out to render the PTFE surface conductive. The surface compositions and microstructures of the graft-copolymerized PTFE films were studied by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), respectively. The PANI chains grafted onto PTFE film surface were similar to the PANI homopolymer. The surface resistance of the aniline graft-copolymerized PTFE film could be reduced to the order of about 104 Ω/sq, compared to the order of 1016 Ω/sq for the pristine PTFE film. Cohesive failure occurred inside the bulk of PTFE film when an epoxy adhesive was applied to peel off the grafted PANI layer from the GMA graft-copolymerized PTFE substrate. The strong adhesion arose from the fact that the PANI chains were covalently bonded onto the GMA graft-copolymeried PTFE film through the curing of epoxide groups of the grafted GMA polymer by the amine groups of the aniline molecules during oxidative graft copolymerization and the amine groups of PANI after the oxidative polymerization of aniline.