Various methods have been exploited to treat oil/water mixtures, but they are not suitable for widespread application due to high cost or low efficiency. Superhydrophobic materials with water-repellent and lipophilic are desirable materials for the separation. Here, composite superhydrophobic coatings, capable of applying to a variety of substrates, were developed using a simple co-blending method of dispersing fumed TiO₂ nanoparticles (NPs) and hydrophobic silica sol into non-fluorinated modified polystyrene resin (MPS). The properties of the coating were investigated by a variety of techniques such as FTIR, FESEM, TG-DSC, and contact angle measurement. The results suggested that the surface had exceptional superhydrophobicity with the WCA as high as 160.8°. The coating remained superhydrophobic after 3 times of sandpaper abrasion. The superhydrophobic surface had excellent self-cleaning properties and could be applied to separate the oil/water mixture. The separation efficiency could be over 96% and remained stable after 5 cycles. It is a great prospect in the treatment of oily wastewater. Furthermore, the reagents and instruments used during the procedure are easily available, so it has the potential for production in large quantities.

Graphical abstract

The superhydrophobic composite coatings for self-cleaning were fabricated by mixing the non-fluorinated modified polystyrene resin (MPS) and two nanoparticles of TiO2 and SiO2. The superhydrophobic composite coatings could be applied to separate the oil/water mixture. The separation efficiency could be over 96%, and remained stable after 5 cycles.