A Molecular Dynamics Simulation on Wettability of a Liquid Droplet on Solid Surface with Nanoscale Inverted Triangular Grooves

Solid surface with nanostructures can effectively regulate interfacial wettability, which has important application prospect in material energy and other fields. Changing the geometric dimension of nanostructures can adjust the wetting property in a certain range, but it has some limitations. Adjusting the solid-liquid energy parameter can further regulate and control interfacial wetting property. However, the effect of energy parameter during greater interval on wettability of droplets on nanostructured surface is rarely reported. Using the molecular dynamics simulations, wettability of a liquid droplet on solid surface with nanoscale inverted triangular grooves was studied with several energy parameters in different intervals. Such wettability can be characterized by penetrating rate. Increasing energy parameter in the four different intervals makes penetrating rate grow within varied ways, which increases firstly and then decreases. The droplet also in turn exhibits a significant wetting state, corresponding to the hydrophobic Cassie state to the hydrophilic Wenzel state in the wetting state map, and then reversed to the hydrophobic Cassie state if the energy parameter exceeds the critical value (~7). At the same time, the spatial distribution of droplet molecules shows obvious regularity, in which underlying atoms evenly distribute in the lattice line or crystal surface, shaped like the epitaxial growth of the solid atoms. The overall understanding of the effect of energy parameter on wettability is obtained, which provides direction to design or regulates wettability in nanostructure surface.