Fabrication of superhydrophobic AAO-Ag multilayer mimicking dragonfly wings

Inspired by the co-coupling of the non-smooth structure and the waxy layer inducing the hydrophobicity of dragonfly wing surface, we developed a simple and versatile method to fabricate a superhydrophobic surface with the dragonfly wing structures. In this work, Ag nanorods grew on highly ordered anodic aluminum oxide (AAO) surface via a galvanic reduction approach. Then the AAO-Ag multilayer was fabricated. Furthermore, the surface free energy of AAO-Ag multilayer was reduced by modifying with perfluorodecanethiol. The modified AAO-Ag multilayer was superhydrophobic and the static contact angle reached as high as 168°. X-ray photoelectron spectra (XPS) were used to characterize the chemical structure of the obtained products. The morphologies of AAO-Ag multilayer was similar to microstructure of dragonfly wing surface and presented hierarchical rough structure. The results showed that the co-coupling of the rough structure and low surface free energy induced the superhydrophobic performance of the AAO-Ag multilayer surface.