Fabrication of superhydrophobic and oleophobic sol–gel nanocomposite coating

Superhydrophobic sol–gel nanocomposite coatings with improved oleophobic property were obtained by incorporation of a perfluoroalkylmethacrylic copolymer in a hybrid sol–gel matrix containing fumed silica nanoparticles. The coatings exhibited a water contact angle (WCA) of 158° and contact angle of 146° for ethylene glycol and 113° for lubricant oil. Though the sol–gel nanocomposite coatings in the absence of fluoropolymer were superhydrophobic with WCA of 155°, they were oleophilic with oil contact angle of < 10°. The enhanced oleophobicity can be attributed to the further lowering of surface energy by the presence of fluoropolymer. FESEM images of the coating showed a highly porous structure with random distribution of aggregates of silica nanospheres. The coatings were characterized using FTIR, EDX and XPS. These studies indicated adsorption of fluoropolymer on the coating surface. The method is simple and cost-effective and can be used for preparing multifunctional water- and oil-repellent self-cleaning coatings on large areas of different kinds of substrates like glass, metal and composites.