Antifouling thin-film composite membranes with multi-defense properties by controllably constructing amphiphilic diblock copolymer brush layer

We developed a novel amphiphilic copolymer architecture for thin-film composite (TFC) membranes to integrate “resistant” and “release” strategies against membrane fouling. Two materials were sequentially grafted on TFC reverse osmosis membrane surfaces via dual surface-initiated atom transfer radical polymerization (SI-ATRP): zwitterionic polymer, poly[2-(methacryloyloxy)ethyl-dimethyl-(3-sulfopropyl) ammonium hydroxide] (pMEDSAH) with strong hydrophilicity and poly(2,2,2-trifluoroethyl methacrylate) (pTFEMA) with low surface energy. According to MD simulation and theoretical quantification, the p(MEDSAH-b-TFEMA)-grafted membranes (i.e. amphiphilic TFC membranes) possess not only strong hydration, but also lower surface energy, which yield the features of both fouling resistant and fouling release properties. The superiority of possessing multi-defense properties was further confirmed by the long-term, multi-cycle membrane fouling and cleaning filtration. Compared with pristine TFC and hydrophilic TFC membranes, the amphiphilic TFC membranes showed not only less water flux decline during the fouling filtration, but also higher water flux recovery after cleaning by water. Both theoretical and experimental results strongly suggest that the amphiphilic TFC membrane is a novel candidate for improving membrane antifouling properties.