Hierarchically-structured artificial water-repellent leaf surfaces replicated from reusable anodized aluminum oxide

Here we present a simple process to synthesize artificial water-repellent leaf structures through the introduction of hierarchical nanostructures to the surface using anodized aluminum oxide templates. Unlike cylindrical nanopores fabricated by conventional anodization, biomimetic hierarchical structures were manufactured by multi-step anodization of nanoscopically pre-patterned Al. From the hierarchical anodized aluminum oxide templates, the perfluoropolyether nanostructures were simply replicated and repeatedly obtained by reusing the anodized aluminum oxide templates without anti-adhesion coating. Upon the investigation of the wettability of perfluoropolyether hierarchical surfaces, it was found that the surface became more hydrophobic (similar to 152A degrees) with the increase of the structural complexity, and are comparable to water-repellent leaf surfaces found in nature.