Effects of Nanostructures on Surface Wettability: A Molecular Dynamics Study

The nanostructured surfaces have attracted much attention owing to its possibility of changing surface wettability as well as the enhancement of interface heat transfer, however, the mechanism has not been clarified yet. In this study, molecular dynamics simulations have been carried out to study the effect of the nanostructures on the wetting characteristics at the solid-liquid interface. The simple Lennard-Jones (L-J) liquid droplet is placed on a solid surface in a shape of molecular-scale unevenness with different height and spacing. The wettability of the solid-liquid interface is examined with evaluating the contact angles at the three-phase interface. The results of the measured contact angles demonstrate that the nanostructures could strengthen the hydrophobic properties for a partial wetting condition, while it is insignificant in a completely wetting case. Furthermore, we compare the results of molecular dynamics (MD) simulations with the classical descriptions and discrepancy among the results is found. A modified description of contact angle in consideration of molecules filling ratio among nanostructures was proposed.