Photostability and dipole orientation of air dielectric barrier discharge processed PVC copolymer

Surface modification of a PVC copolymer film was performed in an air dielectric barrier discharge (DBD) to investigate the photostability and effect of the streamer discharge on the polymer surface. Characterisation of the modified surface by X-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) techniques showed formation of oxidized carbon functionalities at the expense of the saturated alkyl components. Simultaneous oxygenation and hydrophilisation of the air DBD processed copolymer film was revealed by the complementary variation in contact angle and O/C ratios with respect to the applied discharge dose. On the basis of XPS derived Cl/C ratio, the concentration of the C-Cl component of the C (1s) envelop and depth profiling of Cl- ions from SIMS for the modified film showed a selective abundance of chlorinated alkyl chains on the polymer surface. Stability of chemical modifications induced by DBD processing in air was investigated by analysing one-month aged treated film. Since there appears to be no change in concentration of the C-Cl bonds (no loss of Cl) present, it is concluded that the UV radiation emitted from the discharge does not photo-degrade the PVC copolymer surface.