Endowing the Antifouling and Self-cleaning Properties of Poly(ether sulfone) Oil/Water Separation Membrane by Blending with Amphiphilic Block Copolymer Additive

Oil/water separation is a worldwide challenge because large amounts of oily wastewater are produced in our daily life and many industrial processes. There is a growing tendency to employ ultrafiltration membrane for treating oily wastewater due to its low energy consumption, high operation efficiency and environmentally friendly characteristic. Recently, amphiphilic copolymers were designed as additives to fabricate composite membranes through physical blending modification, which has quickly become a research hotspot due to its simple operation. In this work, a novel amphiphilic block copolymer of poly(ethylene glycol methyl ether) block poly(hexafluorobutyl methacrylate) block poly(glycidyl methacrylate) (mPEG-b-PHFBM-b-PGMA) was beforehand synthesized via reversible addition-fragmentation chain transfer polymerization (RAFT). Then, the PES/mPEG-b-PHFBM-b-PGMA composite membrane was prepared by the NIPS method. In the membrane formation process, the hydrophobic PGMA segments in mPEG-b-PHFBM-b-PGMA act as an anchor, which amalgamated with hydrophobic PES molecular. At the same time, the hydrophilic mPEG segments migrated spontaneously to the membrane surface via a "free surface segregation" approach, dragging the low surface energy PHFBM segments onto membrane surfaces. In this way, an antifouling and self-cleaning advanced membrane surface was constructed. The pure water flux and oil flux of the PES/PFG5 composite membrane are around 290.25 and 252.89 L.m(-2).h(-1), respectively. The corresponding values of the PES blank membrane are only 64.10 and 11.09 L.m(-2).h(-1), respectively. Compared with the unmodified PES membrane, the flux recovery ratio increases from 45.75% to 90.15%, while the permeation flux-decline value decreases from 82.70% to 12.87%, suggesting the excellent anti-fouling and self-cleaning property of the modified PES/PFG5 composite membrane. Furthermore, the mPEG-b-PHFBM-b-PGMA copolymer exhibits good stability due to the physical intertwisting and hydrophobic interaction between the PGMA and PES, suggesting the good application prospect of the membrane in oil/water separation.