Activation of polycarbonate (PC) surfaces by atmospheric pressure plasma in ambient air

This paper presents the study of the ambient air atmospheric pressure plasma (APP) treatment of polycarbonate (PC) surfaces to improve the wettability. The APP was generated by dielectric barrier discharge of coplanar electrode arrangement: a Diffuse Coplanar Surface Barrier Discharge (DCSBD), and gliding arc APC 500. The changes in wettability of the PC surfaces were characterized by water contact angle measurement, hysteresis analysis of the water contact angle and surface free energy. We found that both plasma sources led to considerable decrease of water contact angle in first second of the treatments. Surface free energy analysis explained, that the decrease of the water contact angle was related to higher polar components of the surface. The modification of the PC surfaces was further evaluated by X-ray photoelectron spectroscopy that showed that both plasma sources led to increase in concentration of polar functional groups on the PC surface. The main difference between DCSBD and APC plasmas was in the surface morphology which observed by atomic force microscopy (AFM).