Stable superhydrophobic composite coatings made from an aqueous dispersion of carbon nanotubes and a fluoropolymer

An easy method is reported for fabricating a stable superhydrophobic coating made from a composite comprising carbon nanotubes and a fluoroplastic such as polytetrafluoroethylene or perfluoroalkoxy resin (Teflon® PFA). The superhydrophobic coatings with hierarchical structure characteristics are fabricated by a spray coating technique using an environmentally friendly aqueous dispersion containing carbon nanotubes and perfluoroalkoxy resin. Coatings with a contact angle of 153.1 ± 2° and a sliding angle less than 5° are stable under much stress conditions, i.e., either soaking in concentrated hydrochloric acid and concentrated sulfuric acid, or attacking with extreme-pH or ionic-strength solutions. Both the contact angle and sliding angle can be tuned simply by changing the carbon nanotube loading. To further the understanding of the formation of superhydrophobicity, we investigated both the formation of the nano/microscale structures and their effects.