Lattice Boltzmann study on the effects of surface nanostructure on wettability with application in laser scanning fabrication of superhydrophobic surfaces

Nanostructured surfaces with dimensions on a scale of a few millimeters exhibit remarkable hydrophobicity. The geometry of these nanostructures considerably affects their wettability. However, determining the optimal geometry is challenging due to the abundance of geometry parameters and the difficulty in numerically describing their effects on wettability at the mesoscopic scale. In addition, the fabrication of nanostructured surfaces with precise geometries is challenging. We establish a lattice Boltzmann method (LBM) model to address these challenges. We use the model to gain mesoscopic insights into the interaction between droplets and nanostructures. Our model can accurately reproduce contact angles (CAs) on various nanostructured surfaces and enables investigation of the effects of nanostructure geometry on wettability. We optimize the geometry of the nanostructures using the insights provided by the LBM model on the wettability mechanisms. Our analysis indicates that cones with dimensions of 40 µm in width and 33 µm in height exhibit the highest hydrophobicity. We successfully fabricate a superhydrophobic surface with the desired geometry via laser scanning, achieving a CA of 163°. We believe that this approach, which combines the LBM model and laser manufacturing, will enable a better understanding of the wettability mechanism and provide a high-performance approach for fabricating superhydrophobic surfaces.