On the role of the amphiphobic surface properties in droplet wetting behaviors via molecular dynamics simulation

Abstract

Amphiphobic surface combines the advantages of hydrophobic surface and oleophobic surface, and it can repel water and oil simultaneously. The properties of the solid surface have significant effects on the wetting behaviors of droplets on it. However, most studies of the influences of surface properties focus on the hydrophobic or oleophobic surface, but for amphiphobic surface, which has wider applications, the studies are seldom conducted. The molecular-scale mechanism of the difference of wetting behaviors between water and oil droplets has also not been revealed. In this work, the effects of surface characteristic energy ε and surface charge q of amphiphobic surface on the wetting behaviors of water and oil droplets are systematically investigated via molecular dynamics simulation. The results show that the increases of ε and q will decrease the contact angles of water and oil droplets on the amphiphobic surface, and weaken its hydrophobicity and oleophobicity. Compared with the water droplet, ε and q have larger effects on the wetting behavior of oil droplet, which is easier to complete a transition from Cassie to Wenzel wetting state. Moreover, arrangements of oil droplet molecules are more orientational near the amphiphobic surface than that of water droplet molecules.