Molecular mechanisms of hydrophobic transitions

Abstract

This review article provides new insights into the molecular mechanisms of hydrophobicity that emerge within the phenomenological framework of classical capillarity. The thermodynamic analysis of surface phenomena via the Gibbs adsorption equation that forms the basis of the experimental physical chemistry of liquid-fluid interfaces extends with its rigorous implications towards the wetting of solid surfaces. Observations on equilibrium contact angles, contact angle hysteresis, and the dynamics of wetting hitherto based on qualitative results that received fragmentary and eclectic interpretations are accounted for in terms of the values of adsorption pressures that act at the three-phase line. Hydrophobic surfaces and hydrophobic transitions induced by reversible solute adsorption qualify as two distinct limiting cases in this thermodynamic context. The equilibrium and kinetic aspects of the wetting of uniform and chemically heterogeneous surfaces by pure liquids and surfactant solutions is discussed with reference to reversible liquid-fluid interfaces. The importance of the solvent and solute adsorption at the solid-vapor interface for proper assessment of static and dynamic dewetting transitions is particularly addressed.