Improved antifouling and self-cleaning ability of PVDF ultrafiltration membrane grafted with polymer brushes for oily water treatment

[Display omitted] •PVDF membrane was grafted with PNIPAAm-block-PPEGMA through ATRP process with secondary fluorine atoms on PVDF backbone as initiators.•Polymer grafting enhanced the hydrophilicity and brought a thermo-sensitive property to the membrane.•Grafting PNIPAAm from PVDF membrane enables a simple and chemical-free way to clean the fouled membranes.•Grafting PEGMA from PVDF-g-PNIPAAm membrane improved membrane hydrophilicy.•The modified membrane showed antifouling property and improved separation performance for treatment of oily water. This study focuses on the modification of commercial polyvinylidene fluoride (PVDF) membranes using surface-initiated atom transfer radical polymerization (SI-ATRP) method. Poly(N-isopropylacrylamide) (PNIPAAm) was grafted from PVDF surface and then PEGMA was grafted onto the PVDF-g-PNIPAAm membrane. The aim of the research was to prepare membranes that simultaneously have antifouling and self-cleaning properties. PNIPAAm (lower block) was grafted to give the membrane temperature sensitive property and PPEGMA (upper block) was used to improve hydrophilicity. Morphology, topography and chemical composition of the modified membranes were completely characterized. Antifouling and cleaning ability of modified membranes were investigated using synthetic oily water. Moreover, the role of PEGMA polymerization time on the membrane performance was examined. PNIPAAm-b-PPEGMA modified membrane achieved 64% decrease in fouling ratio compared to unmodified PVDF membrane at best condition. The flux recovery was 99.1% for modified membrane at this condition. Furthermore, the unmodified PVDF membrane showed 91.1% oil rejection; while the modified membrane could reject 98.2% oil molecules. The final flux of all modified membranes were higher than unmodified membrane. These results indicated that PNIPAAm-b-PPEGMA modified membranes have excellent fouling resistance and self-cleaning ability.