Coordination-Driven Self-Assembly of PNIPAM on MnO2 Microflowers/CFC Membrane with switchable superwettability for Robust Photo and Thermal Dual-Responsive Oil-Water Separation

To address oily wastewater pollution, a dual-responsive composite membrane with switchable superwettability was fabricated by in situ growth of MnO 2 microflowers on carbon fiber cloth (CFC), followed by coordination-driven self-assembly of catechol-functionalized poly(N-isopropylacrylamide) (PNIPAM). The abundant oxygen vacancies (O v ) on MnO 2 microflowers enhanced photothermal conversion efficiency (24.99% for optimal MC 4 ) and provided active sites for robust PNIPAM anchoring via C-O-Mn coordination bonds. The resulting membrane (PMC) exhibited switchable superwettability: underwater superoleophobicity (150.10°) at 25 o C and underoil superhydrophobicity (150.27°) at 45 o C under heating or NIR irradiation. This enabled efficient separation of diverse oily pollutants, including light/heavy oil-water mixtures and emulsions, with high separation efficiency (> 99.5% for mixtures, > 99.2% for emulsions) and exceptional water flux (25239.89 L m −2 h −1 ). Taking advantages of the in situ grown of MnO 2 on CFC and strong chemical anchoring of PNIPAM on MnO 2 , the photo and thermal dual-responsive PMC membrane maintained excellent stability after mechanical (rubbing, bending, soaking) and chemical (acid/alkaline/saline) challenges, demonstrating superior reusability and durability for practical water purification applications.