Superhydrophobicity and Compressive Stability of Salvinia Surface: Mechanical Analysis and Structural Design

The surface of Salvinia had superhydrophobicity and kept good compressive stability, which was mainly attributed to the dense microscopic eggbeater structure villi on the surface. By means of force equilibrium, a theoretical model was established to analyze the interface mechanical behaviors when a droplet infiltrates the microstructures. Based on the minimum energy principle, a theoretical model was presented to analyze the process of a droplet spreading on the surface of Salvinia reaching a steady state. Combined with numerical simulations, it was found that the superhydrophobicity and compressive stability of the Salvinia were dependent on the morphological and geometric parameters of the microstructure (edge angle phi, number of branching n, width W and spacing D, etc.). By adjusting these geometrical parameters, the surface of the biomimetic structure can maintain a stable Cassie state at 0.63 kPa pressure, and the apparent contact angle is controllable in the range of 121 degrees- 169.8 degrees. The research results provide a theoretical foundation for the structural design of superhydrophobic surfaces with high stability and tunable wettability.