Smart and durable pH-responsive superhydrophobic fabrics with switchable surface wettability for high-efficiency and complex oil/water separation

The oily wastewater has posed a great threat to the environment and human health, and the oil-water mixture is complex and diverse. Therefore, it is crucial to develop a smart and efficient oil/water separation material. In this paper, random polymers containing carboxyl groups were synthesized for surface-modifying hydrophilic SiO2 nanoparticles. Polydimethylsiloxane (PDMS) was then used as the adhesive to fix the modified SiO2 nanoparticles firmly on the fabric surface endowing the fabric with a robust hydrophobic effect. The modified SiO2 nanoparticles not only made the fabric obtain a rough structure but also caused the fabric to have the effect of switchable wettability under the stimulation of pH. In addition, the prepared fabric maintained good mechanical durability and chemical stability after the mechanical abrasion, ultraviolet irradiation, and organic solvent treatment. Interestingly, under the stimulation of pH, the smart fabric could controllably separate different oil/water mixtures (including heavy oil/water and light oil/water) with excellent separation efficiency and high flux even after 20 cycles of separation process. Meanwhile, the pH-responsive fabric material successfully separated light oil/water/heavy oil three-phase oil/water mixture and different kinds of emulsions. Therefore, the prepared pH-responsive superwetting fabric has a broad application prospect in the field of dealing with complex oil/water mixing systems.