Robust superhydrophobic coating with hollow SiO2/PAA-b-PS Janus microspheres for self-cleaning and oil–water separation

Superhydrophobic coating can be widely used in many fields because it is not easily wetted by water like lotus leaves. However, most of superhydrophobic coating is difficult to withstand abrasion attack. Herein, hollow SiO2/PAA-b-PS Janus microspheres were synthesized via emulsion interfacial synthesis method using amphiphilic block copolymer of polyacrylic acid block polystyrene (PAA-b-PS) and hollow NH2-SiO2 microspheres as raw materials in this paper. Because the hemisphere grafting organic polymer chain was hydrophobic and the other hemisphere was hydrophilic and contained amino groups, hollow SiO2/PAA-b-PS Janus microspheres exhibited amphiphilic and asymmetrical nature, which was a typical inorganic/polymer Janus microspheres. Robust superhydrophobic coating was facilely achieved using hollow SiO2/PAA-b-PS Janus microspheres on polyurethane pretreated substrate like leather and fabric. Robust superhydrophobic coating after 90 sandpaper abrasion cycles still retained excellent superhydrophobicity. As expected, robust superhydrophobic coating had prominent self-cleaning property against different pollutants and was capable to separate a variety of oil–water mixtures with ultrahigh separation efficiency. The separation efficiency of robust superhydrophobic coating for oil–water mixture was maintained above 98% even after 40 separation cycles. In total, robust superhydrophobic coating constructed by hollow SiO2/PAA-b-PS Janus microspheres possesses distinguished superhydrophobicity, abrasion resistance, self-cleaning, oil–water separation capacity and universality, which shows a promising application in multifunctional coating.