Effect of washing on surface free energy of polystyrene plate treated by RF atmospheric pressure plasma

Low-temperature plasma can be generated at one atmospheric pressure by applying a radio frequency (RF, 13.56 MHz) voltage between two parallel electrodes, and used for thin film deposition, chemical synthesis, etching, surface treatments and sterilization. The surface properties of a general purpose polystyrene (GPPS) plate treated with RF atmospheric pressure plasma (APP) can be modified by subsequent washing. In this paper, the surface wettability of a GPPS plate treated with RF atmospheric pressure plasma was examined before and after washing. After the washing process, the surface wettability of the GPPS plate was changed as a function of the operating parameters including the treatment time, the distance between the plasma flame and the substrate surface and the treatment power.