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.