Study On The Performance Of Functional Ultrafiltration Membranes Fabricated By Surface Segregation

Functional ultrafiltration membranes have a good prospect in the field of water treatment, biological separation and drug delivery, etc. So far, most of the functional ultrafiltration membranes were designed and fabricated by surface grafting and surface coating. But both of the two methods suffer from the disadvantages of membrane pore blockage, complicated operational conditon and high cost etc., limiting the development and application of functional ultrafiltration membranes. As an in situ and threedimensional alternative method, surface segregation can generate more efficacious antifouling brushes on the membrane surfaces, which has attracted widespread attention. In this study, functional ultrafiltration membranes are fabricated by surface segregation, and the details are summarized as follows:Based on free surface segregation, pH-responsive ultrafiltration membrane was fabricated. pH-responsive amphiphilic copolymers bearing Pluronic F127 and poly(methacrylic acid)(PMAA) segments, abbreviated as PMAAn-F127-PMAAn, were synthesized by free radical polymerization. We investigated the influences of PMAA polymerization degree on the surface composition, surface hydrophilicity, surface chage and pH-responsive property of PES/PMAAn-F127-PMAAn ultrafiltration membranes. During membrane preparation process, PMAA segments were segregated on the membrane surface and the degree of PMAA near-surface coverage was increased with an increase of PMAA polymerization degree. Due to the conformational variation of PMAA segments under different pH values, PES/PMAAn-F127-PMAAn ultrafiltration membranes exhibited significant, reversible and durable pH-responsive property and the pH-responsive ability of the membranes was elevated with the degree of PMAA near-surface coverage.Based on free surface segregation, antifouling ultrafiltration membrane was fabricated. Inorganic nanocomposites of polyzwitterion coated carbon nanotubes(SBMA@CNT) were prepared via precipitation polymerization. We investigated the influences of the dosage of SBMA@CNT on the mechanical strength and antifouling property of PES/SBMA@CNT ultrafiltration membrane. The antifouling property of PES/SBMA@CNT ultrafiltration membrane was significantly elevated after the introduction of SBMA@CNT. The membrane with 1 wt % SBMA@CNT exhibited the best antifouling property(FRR: 98.89 %; Rt: 37.73%).Based on forced surface segregation, antifouling ultrafiltration membrane was fabricated. The amphiphilic block-like copolymer bearing hydrophobic poly(butyl methacrylate)(PBMA), hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate)(PEGMA) and low surface energy poly(hexafluorobutyl methacrylate)(PHFBM) segments was synthesized by free radical polymerization. We investigated the influences of the introduction of PBMA-PEGMA-PHFBM on the surface composition, surface hydrophilicity, surface energy and antifouling property of PVDF/PBMA-PEGMA-PHFBM ultrafiltration membrane, as well as and the influences of different operation conditions(including agitating speed, operation pressure and oil concentration) on the antifouling property. The PVDF/PBMA-PEGMA-PHFBM ultrafiltration membrane exhibited superior antifouling property(FRR: higher than 90%) even under low agitating speed, high operation pressure and oil concentration.