The effect of surface modification by nitrogen plasma on photocatalytic degradation of polyvinyl chloride films

The solid-phase photocatalytic degradation of poly(vinyl chloride) (PVC) films was investigated under the ambient air in order to assess the feasibility of developing photodegradable polymers. Nitrogen plasma was used to modify PVC films to enhance the photocatalytic degradation of PVC with nano-sized anatase TiO₂. The plasma parameter varied in this study is discharge power from 30 to 120 W for a constant treatment time of 60 s and a constant gas pressure of 10 Pa. The photodegradation of the plasma-treated PVC-TiO₂ films was compared with that of pure PVC films and PVC-TiO₂ films performing weight loss monitoring, scanning electron microscopy (SEM) analysis, contact angle measurements, electron spin resonance (ESR), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The wettability of the plasma-treated PVC is improved significantly. ESR revealed that the signal of radicals on the surface of the plasma-treated PVC film was enhanced after the treatment. Furthermore, the weight loss indicated that TiO₂ speeds up the photocatalytic degradation of PVC chains. The SEM image of the plasma-treated PVC-TiO₂ film showed a lot of crack on the film surface after irradiation. XPS indicated that the C and Cl atomic concentration reached minimum values on the surface of plasma-treated PVC-TiO₂ under identical photocatalytic condition. The experimental results reveal that plasma treatment can obviously enhance the photocatalytic degradation of PVC.