Surface modification of poly (tetrafluoroethylene) function materials by plasma-induced graft copolymerization of acrylic acid

The plasma graft polymerization of acrylic acid (AAc) on the poly (tetrafluoroethylene) (PTFE) surface was carried-out in two steps: the formation of peroxides on the PTFE surface by the plasma treatment and the AAc graft polymerization from the peroxides. Peroxides are known to be the species responsible for initiating the graft polymerization when PTFE reacts with AAc. We chose different parameters of plasma treatment to get the optimum condition for introducing maximum peroxides (2.87 X 10(-11) mol/cm(2)) on the surface. The influence of grafted reaction conditions on the grafting degree was investigated. The maximum grafting degree was 25.2 mu g/cm(2). The surface microstructures and compositions of the AAc grafted PTFE film were characterized with the water contact angle meter, attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Contact angle measurements revealed that the water contact angle decreased from 108 degrees to 41 degrees and the surface free energy increased from 22.1 X 10(-5) to 62.1 X 10(-5) N/cm by the grafting AAc. The hydrophilicity of the PTFE surface was greatly enhanced. The time dependent activity of the hydrophilicity of the grafted surface was better than that of the plasma treated film.