Papillae mimetic hairy composite spheres towards lotus leaf effect coatings

An effective approach is proposed to fabricate a robust superhydrophobic coating constructed from hairy composite spheres. The hairy spheres mimic structure of the papillae on the surface of lotus leaf. The synthesis is based on template method and the corresponding PANi hairy spheres are prepared by polymerization induced diffusion growth via nanosized channels of a polymer cage. The composite spheres become more robust by coating a layer of inorganic materials onto the PANi hairy spheres. By using a middle adhesive layer of epoxy resin, the hairy spheres can be tightly attached to the substrate. The superhydrophobic coating is achieved with a contact angle of 159.9 ± 1.9° and tilt angle below 2° by a post hydrophobic modification with octadecyltrichlorosilane. Such coating is robust enough to resist water flushing and organic solvents. This method can be scaled up for almost all kinds of substrates.