Surface modification of polyester films by RF plasma

Plasma treatment of PET films was carried out under argon, followed by expo sure to an oxygen atmosphere. The films underwent considerable changes in s urface composition and morphology, as demonstrated by contact angle measure ments, FTIR-ATR, AFM, and XPS. It was found that the surface acquired oxyge n containing polar functional groups such as -C=O, -OH, and -OOH, which inc reased in number as the plasma treatment time increased. During storage, th e treated films underwent significant surface reorganization, and both the time and temperature contributed to the increase in the contact angle. As r evealed by AFM measurements, these changes were accompanied by an increase in roughness in the form of ridges. The ridges were observed to grow in hei ght with increasing treatment time, although their spacing showed little ev olution. A correlation among the observations obtained from various techniq ues was established, giving a comprehensive picture of the structure and dy namics of plasma-treated PET surfaces. (C) 2000 John Wiley & Sons, Inc.