Functional silica film on stainless steel mesh with tunable wettability

A series of functional silica films on stainless steel meshes are fabricated by simple sol–gel process using tetraethyl orthosilicate (TEOS) and methyltriethoxysilane (MTES) as precursors and post-thermal treatment or hydrophobization. The wettabilities of these meshes can range from superhydrophobicity and superoleophilicity to superamphiphilicity or amphiphobicity. The tunable wetting states are controlled by changing surface chemistry or morphology. Firstly, methyl-endcapped silica film with superhydrophobic and superoleophilic property is formed using a dip-coating method; then, the methyl groups are removed by adequate annealing, and the mesh exhibits superamphiphilic property; finally, after surface modification by perfluorooctyltriethoxysilane, the amphiphobic mesh is obtained. These stainless steel meshes with different wettabilities may act as “smart” switches, which can allow oil or water pass through the mesh or not selectively, and this is potential to be used in intelligent oil/water separating device.