Zwitterionic-functionalized GO/PVDF nanocomposite membranes with improved anti-fouling properties

Herein, novel anti-fouling nanocomposite membranes were developed by the incorporating of zwitterionic-modified graphene oxide (GO-g-PMSA) sheets bearing -SO3- and -NH3+ groups into the polyvinylidene fluoride (PVDF) matrix. The GO-g-PMSA nanosheets were synthesized by growing of PMSA zwitterionic brushes on GO surface by the redox graft polymerization via the "graft-from" strategy, causing the twofold advantages of increasing the Go dispersibility in the membrane matrix and giving more antifouling property to GO. The incorporation of the zwitterionic additive in the PVDF membranes significantly improved water affinity and surface hydrophilicity of the nanocomposite membranes. Comparing to pure PVDF membranes and GO/PVDF membranes, as-prepared GO-g-PMSA/PVDF membranes showed evident improvement in anti-fouling properties due to the smoother surface and the more hydrophilic surface in presence of PMSA brushes. An optimum antifouling performance was obtained for 1 wt% GO-g-PMSA/PVDF membrane, e.g. FRR = 95.3%, R-r = 32.3% and R-ir = 4.7% (testing with 1 g.L-1 Buffer phosphate BSA solution at 0.7 MPa). The salt rejection experiments also showed high salt ions rejection. Taken together, the results confirmed that zwitterionic polymer modified GO as an antifouling additive can be potentially applied to fabricate antifouling nanocomposite membranes.