Fabrication of flexible photo-responsive mesh with reversible wettability and enhanced mechanical damage resistance for efficient oil/water separation

Oil/water separation constitutes a significant global challenge owing to the challenges in selectively isolating either water or oil from mixtures encountered in practical settings. To overcome this obstacle, photo-responsive materials capable of reversible wettability shifts have been utilized for oil/water mixture separation, capitalizing on their wetting behavior. In this work, we employ spray-coating to engineer smart surfaces that transition reversibly between hydrophilic and hydrophobic states upon UV/vis irradiation. The resultant modified polyester (PES) mesh, functionalized with a hydrophobic polydimethylsiloxane (PDMS) coating, ZnO-tetrapod (ZnO-T), and 4,4′-diaminoazobenzene (DAAB), displays a porcupinefish-like surface morphology. This architecture confers upon the mesh a significantly reversible photo-responsive wettability, coupled with improved resilience against mechanical damage. The water contact angle measures approximately 140.0° under visible light and decreases to approximately 10.0° upon exposure to 365 nm UV light. The engineered PES surface achieves photo-responsive removal of oil or water from oil/water mixtures ("oil-removing" and "water-removing"). In addition, the porcupinefish-like topology of the modified PES imbues it with significant resistance to repeated mechanical deformation and damage, suggesting suitability for diverse real-world applications.