Ultrathin perfluoropolyether films - Influence of anchoring and mobility of polymers on the tribological properties

The tribological behavior of ultrathin films of hydroxyl terminated perfluoropolyethers attached to smooth silicon surfaces was studied in pin-on-disk experiments. The frictional properties of the films, which consisted of either physically adsorbed or chemically bonded polymer or a combination of both, was measured in sliding contact and lubricant loss was studied simultaneously by scanning microellipsometry. Prior to these experiments the kinetics of attachment attachment of the polymer to silicon surfaces and the behavior of the polymer at high temperatures was investigated in order to obtain reproducible conditions for the deposition of the lubricant films and to rule out the occurrence of thermal degradation during film deposition. The tribological investigations showed that the lifetime of the surfaces with the attached boundary lubricant was strongly dependent on the mode of attachment of the polymer. The best tribological behavior was observed in films which contained both chemisorbed and physically adsorbed material.