Transferrable Superhydrophobic Surface Constructed by a Hexagonal CuI Powder without Modification by Low-Free-Energy Materials

A new route combining a facile wet-chemical process and spin coating was developed to fabricate a CuI film assembled by hexagonal crystals. Remarkably, such a CuI film displays excellent superhydrophobicity without further modification by low-free-energy materials (thiol or fluoroalkylsilane). The special wettability is attributed to a hierarchical morphology of CuI crystals with two length-scale roughnesses and the nature of the material itself. Importantly, this superhydrophobicity is quite stable and the water contact angle of the as-prepared sample only decreases slightly, even when it is kept in air for about half a year. The superhydrophobicity of the as-prepared CuI powder is a bulk property of the material and not just of its surface, so such a powder coating could then prove useful in conferring superhydrophobicity to other surfaces to which it is applied. These facts might improve its practical application with environmental friendship in superhydrophobic coatings.