Hierarchical Superhydrophobic Surfaces Fabricated by Dual-Scale Electron-Beam-Lithography with Well-Ordered Secondary Nanostructures

Recent studies on superhydrophobic surfaces have revealed the important roles of structural hierarchy in the overall properties of these surfaces. Here, a novel, versatile, and efficient technique is introduced for fabricating macroscopic hierarchical superhydrophobic surfaces with both well-defined primary microstructures and well-ordered secondary nanostructures using electron-beam lithography. With this technique, the engineering capability of controlling the size, shape, and distribution of the secondary-features is demonstrated, which allows a systematic and quantitative study of the individual effects of these parameters. Superhydrophobic surfaces produced by this new technique exhibit two distinctive wetting behaviors, high and low adhesion. The structural characteristics and structure-property relations of each of those two regimes are discussed.