Improving surface oleophobicity by dual-scale hierarchical structure design

Through molecular dynamics simulations, the wetting characteristics of oil droplets on solid surfaces with nanostructures were investigated. The oil and water droplets on the smooth wall were studied through simulation and experimental methods. Further, to analyze the influence of the different structural parameters on hydrophobic and oleophobic characteristics, the wetting states of water droplets and oil droplets on the surface of the same single-scale square pillar structure were compared. The simulation results reveal that the hydrophobic effect of water droplets was better than that of oil droplets on the smooth wall and same single-scale square pillar structure. However, the design and improvement of dual-scale hierarchical structure could effectively improve the oleophobic property of the oil droplets, and the contact angle could be increased, rendering the oil droplets on the surface more prone to the Cassie state. By optimizing the dual-scale structure, increasing the width of the secondary hierarchical structure could make the oil droplets close to the superoleophobic state. In the present research, an effective method for improving surface oleophobicity by dual-scale hierarchical structure design is provided.