Surface analysis of poly(ethylene naphthalate) (PEN) films treated at atmospheric pressure using diffuse coplanar surface barrier discharge in air and in nitrogen

Surface modification of poly(ethylene naphthalate) (PEN) films by Diffuse Coplanar Surface Barrier Discharge (DCSBD) in ambient air and nitrogen at atmospheric pressure was studied at short plasma exposure times from 1 s up to 10 s. Chemical changes in the surface composition after the plasma treatments were studied using a high resolution XPS (X-ray Photoelectron Spectroscopy). The water contact angle was reduced from an initial value of 79° to values of 31° and 20° for the ambient air and nitrogen plasma treatments. After 3 days of storage in ambient air the contact angles were still about 50° and 40°, respectively. The polar component of surface energy was changed by the aging significantly less than the total surface energy. Despite the marked increase in the surface energy, the plasma treatment had no significant influence on the surface morphology.