Mussel-inspired cotton fabric with pH-responsive superwettability for bidirectional oil-water separation

With the deteriorating environmental pollution by oil spill accidents and industrial sewage emissions, stimuli-responsive superwettable materials have been of considerable interest for its intriguing application in oil-water separation. Herein, we report a facile room temperature method to fabricate mussel-inspired cotton fabric with pH-responsive superwettability, by combining in situ generation of silver particles to construct roughness with self-assembly of long alkyl thiols terminated with methyl and carboxyl groups to endow hydrophobicity and responsiveness. The fabricated pH-responsive cotton fabric showed superhydrophobicity with water contact angle (WCA) up to 153 degrees under acidic and neutral conditions while superhydrophilicity with WCA at 0 degrees under alkaline condition. Importantly, the cotton fabric was successfully applied in bidirectional oil-water separation, exhibiting high separation efficiency and excellent reversibility. Furthermore, the pH-responsive cotton fabric also demonstrated superior self-cleaning property and antibacterial activity to E. coli and S. aureus. Our method to construct pH-responsive cotton fabric is simple, and no special techniques, chemicals or control of atmosphere is required. Our findings conceivably stand out as a new tool to fabricate functional superwettable materials and surfaces with responsiveness to external stimuli for various oil-pollution treatments and other potential applications.