Wetting as an emergent property of water: reformulating Young equation on molecular grounds

Abstract

Young equation provides a remarkably successful macroscopic description of wetting, yet its molecular origin (particularly for water) has remained elusive for over two centuries. Here we make the molecular basis of aqueous wetting explicit by reformulating it in terms of a molecular wetting coefficient, omega m, which quantifies how an interface compensates the intrinsic energetic cost of hydrogen-bond defects relative to bulk water. Across a broad and continuous spectrum of hydrophilicities, spanning chemically diverse experimental and model surfaces, macroscopic contact angles collapse onto a single universal master curve when expressed through omega m. This molecular reformulation closes Young and Young-Dupre relations on energetic grounds, establishing a unified and predictive physical link between wetting, adhesion, cavitation, and nanoconfined filling. By anchoring interfacial behavior to waters intrinsic hydrogen-bond energetic scales, our results reveal wetting as an emergent property of water itself, rather than a surface-specific attribute and provide a transferable molecular framework that recalibrates energetic intuition and guides the rational design of aqueous interfaces. (This document is the unedited Author version of a Submitted Manuscript subsequently accepted for publication in J. Am. Chem. Soc. For the published version, which includes a more complete molecular-thermodynamics grounding of the method see the published version)