ADHESION HYSTERESIS AND FRICTION

The kinetic friction forces between semispherical lenses of elastomeric poly(dimethylsiloxanes) (PDMS) and chemically modified mica surfaces were measured al a low sliding speed (0.02 mm/s). The surface of mica was modified using self-assembled monolayers of alkyl- and fluoroalkylsilanes. Even though the surface free energy of the fluorocarbon monolayer is lower than that of the hydrocarbon monolayer, its friction against PDMS was found to be greater than that of the hydrocarbon monolayer. The values of the friction forces do, however, follow the same general trend as the hysteresis of adhesion between PDMS and the monolayer-coated mica surfaces. This study provides evidence that the hysteresis of adhesion is an important consideration for understanding friction between surfaces.