Molecular Simulation Study on the Wettability of a Surface Corrugated with Trapezoidal Nanopillars

Abstract Using all-atom molecular dynamics (MD) simulation, we investigate the wettability of a surface patterned with the trapezoidal nanopillars. The dewetting and wetting of the gap between pillars are, respectively, related to the Cassie-Baxter (CB) and Wenzel (WZ) states of a macroscopic water deposited on the pillared surface. We examine the (de)wetting transition by varying the pore structure between the pillars from an open (inverted trapezoid) to closed (trapezoid) geometry. The molecular structures and relative stabilities of various intermediate states existing between the WZ and CB states are uncovered. By identifying the transition states, we estimated the free energy barriers for the wetting and dewetting transitions. The reentrant pillars enhance the resistance to the wetting transition while facilitating the reverse transition, qualifying as the best geometry to be used for a superhydrophobic surface.