Based on molecular dynamics simulations, we found a nonmonotonic relationship between the contact angle of water droplets and the surface polarity on a solid surface with specific hexagonal charge patterns at room temperature. The contact angle firstly decreases and then increases as polarity (denoted as charge q) increases from 0 e to 10 e with a vertex value of q = 0.5 e. We observed a different wetting behavior for a water droplet on a conventional nonwetted solid surface when q <= 0.5 e, and a water droplet on an ordered water monolayer adsorbed on a highly polar solid surface when q > 0.5 e. The solid-water interaction, density of water, hydrogen bonds, and water structures were analyzed. Remarkably, there was up to six times difference in the solid-water interactions despite the same value of the apparent contact angle values.
Qi, CH,Zhou, B,Wang, CL,et al. A nonmonotonic dependence of the contact angles on the surface polarity for a model solid surface[J]. PHYSICAL CHEMISTRY CHEMICAL PHYSICS,2017-01-01,19(9):6665-6670.
