Fabrication of a robust superhydrophobic polyurethane sponge for oil-water separation

In this study, a robust superhydrophobic ZnO microparticle coating was applied to the surface of a polyurethane sponge through a simple solvothermal and chemical vapour deposition method. The thickly hierarchical ZnO microparticle and the long chain alkyl of hexadecyltrimethoxysilane make the sponge exhibit excellent superhydrophobicity and superoleophilicity. By combining excellent superwetting characteristics and a larger surface area, the resulting sponges exhibited high oil-absorption capacity and selectivity for oil-water separation. The durability of the sponge was investigated by two methods, one is ultrasonication in acetone and hexane, the other is anti-resistance in acid and alkali solution. Reusability was tested by repeated absorption-desorption processes. Owing to the good adhesion between the coating and the sponge, the as-prepared sponge shows high durability and reusability. Moreover, the sponge can degrade toxic methylene blue under ultraviolet light irradiation. Therefore, this paper offers a simple and low-cost strategy for the fabrication of absorption materials.