INTERFACIAL FORCES

The past few years have witnessed tremendous advances in experimental and theoretical techniques for probing both the static and dynamic properties of surfaces at the angstrom level. Here we review how these advances have furthered our fundamental understanding of adhesion-particularly those processes that contribute to energy dissipation during adhesion and separation (loading-unloading cycles), and friction-particularly how the dynamic (e.g., viscous and rheological) properties of liquids in ultrathin films differ from the bulk liquid properties, and how this affects the friction forces of lubricated contacts. The emphasis will be on "ideal" surfaces and interfaces, i.e., surfaces that are molecularly smooth, and interfacial films that are no more than a few molecular layers thick.