Surface modification of polyethylene terephthalate and polylactic acid by atmospheric pressure cold plasma jet

Atmospheric pressure plasma jets have been established as suitable sources of low-temperature and non-equilibrium plasmas¹. In this paper, an atmospheric pressure plasma jet sustained in helium/oxygen mixture has been used to modify the surface properties of Polyethylene Terephthalate (PET) and Polylactic acid films. The surface properties of the untreated and plasma treated PET and PLA samples were characterized using a research-grade VCA Optima Goniometer and using drop shape analysis method. Two different testing liquids of deionized water and dimethyl sulfoxide have been used and the surface energy of the PET and PLA samples has been determined. Next, the effect of RF plasma power, the distance between sample and nozzle, and treatment time were investigated. From these results, it was found that the water contact angle of untreated PET sample is 102 C, while it decreases to 35 C after 5 second of plasma exposure due to the introduction of oxygen containing functional groups on polymer surface. Moreover, it was found that, the best plasma treatment can be obtained with applying RF plasma power of 80 W and a distance of 5 mm between PET samples and plasma jet´s nozzle. One can therefore conclude that atmospheric pressure non-thermal plasma can be effectively used to enhance the surface wettability and surface energy of the PET films and thus enhance their biomedical applications.