Atmospheric air and liquid-film DBD plasma using sine AC excitations for purpose of improving the hydrophilicity of PTFE

In this paper, the hydrophilic properties of PTFE were improved by using liquid-film DBD at atmospheric pressure and compared with air DBD. Results obtained indicate that the liquid-film DBD can produce more active species and have a more stable discharge pattern, and its gas temperature is only 450 K which is lower than that of air DBD (580 K). When the treatment time is 10 s, a water contact angle (WCA) of 65.3° was obtained after liquid-film DBD plasma treatment, which was much lower than that treated by air DBD plasma (75.1°). The liquid-film DBD plasma treated PTFE exhibited no damage with the increasing treatment time in the SEM analysis. Chemical analysis by FTIR and XPS spectrum for the untreated and liquid-film DBD modified PTFE did not show a change in their chemical structure and introduced more N- and O-containing functional groups on the PTFE surface. And this result was also verified by TEM/EDX.