Chemical and morphological modification of polymers under a helium–oxygen dielectric barrier discharge

In this work, the surface modifications of various polymer films due to helium–oxygen dielectric barrier discharge (DBD) exposure operating under atmospheric pressure are reported. The polymer films studied include ultra high molecular weight polyethylene, polyamide, polytetrafluoroethylene and polyimide. Experimental results reveal increased hydrophilicity and surface energy of the plasma exposed polymers. This is attributed to the presence of oxygen containing groups grafted onto the surface during plasma treatment, as confirmed by X-ray photoelectron spectroscopy (XPS) analysis. Scanning electron microscopy (SEM) data show the appearance of micro depressions, the size of which depends on the chemical structure and the treatment time, suggesting that mild etching occurs in a predicted fashion. Most importantly, this uniform modification occurs within a few seconds of exposure, time comparable to continuous on-line industrial processing.