Photoinitiated poly-N-isopropylacrylamide for temperature-responsive self-cleaning membranes in oil-water separation

Membrane fouling remains one of the primary obstacles hindering the sustainable development of membrane technology. This study pioneers the controlled growth of PNIPAM hydrogel on TA/Fe 3+ /CA coatings via surface UV photocatalysis, resulting in the fabrication of temperature-responsive PNIPAM@PVDF-Fe/CA membranes featuring thermosensitive PNIPAM hydrogel coatings. The modified membrane's water contact angle decreased from 78° to 36° and achieved complete wetting within 2 s. Water absorption increased from 204 % to 236 %, while separation efficiency improved to 97.8 %. Furthermore, the PNIPAM hydrogel remains in a swollen state at room temperature. When the temperature approaches 32 °C, it undergoes a dramatic volume contraction. This rapid and reversible hydrophilic-hydrophobic transition, accompanied by significant changes in polymer volume, enables the membrane to achieve a high flux recovery rate of 97.29 % during 30–50 °C cyclic cleaning cycles, demonstrating outstanding thermally-induced self-cleaning capability. This study provides a novel approach for constructing hydrogel coatings on membrane surfaces while enabling recycling of modified raw materials, even after multiple cycles of modification, stable modified membranes can still be prepared. The thermosensitive response holds potential for enhancing membrane performance. Combining excellent mechanical properties with recyclability, this membrane demonstrates significant application potential in wastewater treatment.