CHARACTERIZATION OF POLY(TETRAFLUOROETHYLENE) SURFACES BY ATOMIC FORCE MICROSCOPY- RESULTS AND ARTIFACTS

The surfaces of virgin and chemically etched poly(tetrafluoroethylene) (PTFE) have been studied using atomic force microscopy (AFM) in both contact and tapping modes. While attempting to perform AFM in contact mode on this relatively soft polymeric material, tip-induced imaging artifacts (presumably due to blunt tips and tip-to-surface interactions) were identified when the results were compared to scanning electron microscopy (SEM) surface images. When subsequent AFM imaging was performed in tapping mode it was apparent that these tip-induced artifacts were eliminated. Comparable tapping mode AFM and SEM images were obtained for even the highly porous, unstable surface that results from sodium naphthalenide etching of PTFE. AFM imaging in tapping mode of virgin and etched PTFE surfaces shows the three-dimensional character of the etched surface necessary for mechanical interlocking and resultant strong adhesion.