The effect of surface structure and arrangement on wettability of substrate surface

Abstract

Molecular dynamics simulation was used to simulate the wetting of water droplets on surfaces patterned with different texture structures. Through the study of texture structures with different rough elements, we find that the wettability is closely related to the texture structure, and the molecular dynamics contact angles of different wetting modes are in good agreement with the predicted value by the Cassie-Baxter equation, in which the influence of gravity is negligible. In order to investigate this phenomenon in detail, we analyzed the wetting states, contact angles, density distributions of droplets on different surfaces, radial distribution functions of different hydration layers, grid distribution of hydrogen bonds and density of hydrogen bonds. The results showed the arrangement of water molecules in the first hydration layer and the distributions of hydrogen bond grid have a substantial impact on wettability of rough surfaces. The influence mechanism of the surface structure on the wettability is explained from the atomic level. Meanwhile, the consistency between molecular dynamics simulation and Cassie-Baxter equation show that the contact angles increase with the decrease of solid surface area fraction even if the surface texture structures are different.