TERMINAL ATTACHMENT OF PERFLUORINATED POLYMERS TO SOLID-SURFACES

Physisorption and chemisorption of perfluoropolyethers on solid surfaces is investigated using infrared spectroscopy, microcalorimetry, ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy. Physisorbed polymers show shifts of vibrational modes to lower frequencies in a few nanometers thick films, indicating interactions with the solid surfaces. Hydroxyl-terminated polymers are thermally attached to solid surfaces, and their thicknesses increase to saturated values with increasing heating time. The thermally attached thin polymer film consists of strongly physisorbed material as well as chemisorbed material. Strongly physisorbed polymer is slowly displaced from the surface by polar, low-molecular-weight compounds such as water or alcohols. This is to be expected on the basis of microcalorimetric results, which yield higher heats of immersion with water than with reactive perfluoropolyethers. Atomic force microscopy experiments show that the mobility of the polymer remaining on the surface decreases substantially as the amount of the physisorbed material decreases. (C) 1994 John Wiley & Sons, Inc.