The Consequences of Water Between Two Hydrophobic Surfaces in Adhesion, Friction, and Wetting

The contact of two hydrophobic surfaces in water is of importance in biology, catalysis, material science, and geology. A tenet of hydrophobic attraction is the release of an ordered water layer, leading to a dry contact between two hydrophobic surfaces. The molecular nature of the contacting interface underwater impacts a variety of interfacial processes such as adhesion, friction and wetting.   Although the water-free contact has been inferred from numerous experimental and theoretical studies, this has not been directly measured. To better understand the role of water in interfacial phenomena I couple macroscopic measurements with surface sensitive molecular spectroscopy, sum frequency generation spectroscopy (SFG).  By combining tools such as contact mechanics, contact angles and sliding friction in conjunction with SFG,