Facile Fabrication of Superhydrophobic and Underwater Superoleophobic Coatings

Water-repellent and water-loving components are usually used to prepare superhydrophobic and underwater superoleophobic surfaces, respectively. In this work, a facile approach for the fabrication of coatings with the opposite superwettabilities is presented. Hydrophilic nanoparticles (TiO₂, SiO₂, and Al₂O₃) and fluorocarbon surfactants were mixed in water. The obtained aqueous suspensions were simply dipped, brushed, or sprayed onto various substrates, such as fabric, sponge, cotton, nickel foam, stainless steel mesh, copper sheet, glass, and ceramic. The prepared coatings show superhydrophobic and underwater superoleophobic properties with contact angles above 150° and sliding angles below 10°, and they exhibit high resistance to liquid impact, sandpaper abrasion, and acid/base treatment. Taking advantage of its unusual superwettability, the coated fabric can be used for on-demand oil-water separations without a continuous external stimulus. The proposed coatings with opposite superwettabilities will demonstrate the complementary advantages in a variety of interfacial applications.