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

We develop a theory for the maximum (Young's) contact angle of wetting ( ${\Theta }_m$ ) for metals based on the electrochemical work function (E-WF) and interfacial interactions at the droplet surface. In our theory, $\cos \hspace{0.17em}{\Theta }_m$ is the difference of spreading quotient ( ${\xi }_s$ ) of metal and retraction quotient ( ${\xi }_r$ ) of liquid. The spreading quotient, ${\xi }_s$ (<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, ${\xi }_r$ (<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 ${60}^{°}<{\Theta }_m<{80}^{°}$ . Theoretical predictions are in agreement with the experimental and MD simulation data.