Role of Work Function and Potential of Zero Charge on Wetting of Metals

Abstract

We develop a theory for the maximum (Young’s) contact angle of wetting ($$) for metals based on the electrochemical work function (E-WF) and interfacial interactions at the droplet surface. In our theory, $$ is the difference of spreading quotient ($$) of metal and retraction quotient ($$) of liquid. The spreading quotient, $$ (<1), is ratio of E-WF of wet to WF of dry metal and is a measure of spreading tendency and dipolar orientational disorder. The retraction quotient, $$ (<1), is ratio of molecular interfacial interaction energy to the cohesion energy of the liquid, which is a measure of the retraction of drop. The resistance to wetting is governed by the intrinsic electric-field-induced dipolar orientational order on the metal, charge reorganization, interlayer dipole–dipole interactions, and surface tension. An increase in E-WF and a consequent positive shift in PZC also promotes dewetting. The hydrophilic nature of the clean metal surfaces shown as $$. Theoretical predictions are in agreement with the experimental and MD simulation data.