Antifouling modification of PVDF membranes via in situ mixed-charge copolymerization and TiO2 mineralization

This study proposes a novel strategy to fabricate antifouling UF membrane with integrated zwitterionic and TiO2 functionality via in situ mixed-charge copolymerization and TiO2 mineralization. The mixing of positively and negatively charged monomers at the molecular level endows membrane surface with balanced mixed-charge zwitterionic functionality, and the in situ TiO2 mineralization endows membrane surface with well-dispersed TiO2 nanoparticles. Thanks to the unique hydrophilicity of mixed-charges and TiO2, the obtained PVDF/P(MAA-TA)-TiO2 membrane shows greatly enhanced surface hydrophilicity. The outstanding hydrophilicity of the PVDF/P(MAA-TA)-TiO2 membrane significantly improves permeability and protein rejection compared to that of the unmodified PVDF membrane. What's more, the PVDF/P(MAA-TA)-TiO2 membrane exhibits excellent antifouling capability against protein with flux recovery rate and fouling removal efficiency about 100%. Results of detailed fouling analysis indicate that both surface fouling and pore fouling were limited on the PVDF/P(MAA-TA)-TiO2 membrane. The antifouling performance is mainly attributed to the synergistic hydrophilicity of mixed-charges and TiO2, and meanwhile the decrease in the surface electronegativity and pore size also plays a role. Results of this study provide a facile and scalable method for designing antifouling UF membrane, and highlight the promising potential of mixed-charges and TiO2 synergy for manipulating hydrophilic and antifouling modification of UF membranes.