A superhydrophobic coating on aluminium foil with an anti-corrosive property

A superhydrophobic coating with an anti-corrosive property has been fabricated on aluminium foil by a simple sol–gel method with polystyrene spheres (PS) included as a removable template. The effects of the size of PS on the surface structure and the superhydrophobicity have been researched. When the size of PS is 200 nm, the prepared coating shows a high static water contact angle (CA) larger than 150° but also a large adhesive force with the substrate, and the water droplet can be pinned on the substrate tilted at any angle. When the size of PS is 500 nm, the prepared coating has a CA as high as 160°, and the water droplet can roll off the substrate easily. Under this circumstance, the coated aluminium foil is also found to possess good chemical stability and, in particular, an anti-corrosive property. Thus the CA remains nearly unchanged after exposure to air for one year or immersion in an acid solution for 5 h.