Direct Measurement of Solid-Liquid Interfacial Energy Using a Meniscus
Jingcheng Ma, Ishrat Zarin, Nenad Miljkovic
Abstract
Solid-liquid interactions are central to diverse processes. The interaction strength can be described by the solid-liquid interfacial free energy (${\ensuremath{\gamma}}_{\mathrm{SL}}$), a quantity that is difficult to measure. Here, we present the direct experimental measurement of ${\ensuremath{\gamma}}_{\mathrm{SL}}$ for a variety of solid materials, from nonpolar polymers to highly wetting metals. By attaching a thin solid film on top of a liquid meniscus, we create a solid-liquid interface. The interface determines the curvature of the meniscus, analysis of which yields ${\ensuremath{\gamma}}_{\mathrm{SL}}$ with an uncertainty of less than 10%. Measurement of classically challenging metal-water interfaces reveals ${\ensuremath{\gamma}}_{\mathrm{SL}}\ensuremath{\sim}30--60\text{ }\text{ }\mathrm{mJ}/{\mathrm{m}}^{2}$, demonstrating quantitatively that water-metal adhesion is 80% stronger than the cohesion energy of bulk water, and experimentally verifying previous quantum chemical calculations.