Comparative study on the effect of RF and DBD plasma treatment on PTFE surface modification

This paper reports, in a comparative method, the effect of dielectric barrier discharge (DBD) plasma and radio frequency (RF) plasma on the surface wettability, chemistry and microstructure changes of the surface of polytetrafluroethylene (PTFE). Both types of plasma could improve the PTFE surface wettability significantly owing to the changes in surface chemistry and surface microstructure. The high-energy species in high-vacuum (HV) plasma cause the PTFE surface severely etched and causing decomposition of outmost layer of PTFE, results in the evolution of tetrafluoroethylene via scission of the (CF2)_n chain to yield oligomeric segments. In comparison, few heavy species in DBD plasma have high enough energy to cause the scission of the (CF2)_n chain to yield oligomeric segments, thus less etching effect. The contact angle variation with energy dose on RF plasma-treated surface demonstrated a two-stage decrease behaviour: an initial fast decrease stage followed by a levelled-off stage. In comparison, three stages of behaviour are evident for DBD plasma-treated surface. A drastic decrease of the contact angle was recorded during early DBD plasma treatment (at low energy dose), followed by a steady stage and then a slow recovery stage.