The Preparation And Properties Of PVDF Organic/ Inorganic Nanocomposite Membrane

Polyvinylidene fluoride (PVDF) is a kind of optimizing membrane materials, for pressure resistance, high-performance water treatemt, has been widely used in microfiltration, ultrafiltration and other fields. While, owing to hydrophobic nature, PVDF porous membrane shows poor permeability and easily suffers from pollution of protein when applied in the water phase separation system. Hence, the improvement of PVDF porous membrane surface hydrophilicity is considered to be a useful approach to enhance the permeability and antifouling resistance of protein. However, hydrophilicity modification can’t inhibit fouling owing to bacterial and dye etc. Hence, based on the hydrophilicity modification of PVDF porous membrane in this paper, PVDF/TiO2-g-PNIPAAm, PVDF-g-PCBMA/Ag and PVDF-g-PCBMA/TiO2 nanocomposite membranes were respectively prepared and the antifouling resistance of modified PVDF membrane was systematically studied.This paper was consisted of three parts.(1) Surface hydrophilic and thermo-responsive PVDF/TiO2-g-PNIPAAm membrane was prepared by blending a novel nanoparticle (TiO2-g-PNTPAAm) in the casting solution. Then the influence of this nanoparticles on the morphology and structure、hydrophilicility and antifouling ability of blended membrane were investigated systematically, especially the thermo-responsive property. The results showed that the TiO2-g-PNIPAAm nanoparticles improved the hydrophililicity and antifouling performance, and endowed a good thermo-responsive ability to the blended membrane. The initial contact angle of membranes dropped by about 32° at 20℃. Moreover, the contact angle from 61.2° to 78.43°from 20℃ to 40℃, the water flux showed a significant temperature-sensitive, up to about 2 times.(2) PVDF-g-PCBMA/Ag nanonanocomposite membrane was prepared by the surface grafting-chemical reduction combination method and systematic studies conducted to investigate the effect of combining PCBMA and Ag on the membrane hydrophilicity and antifouling resistance of protein and bacterial. According to the results, it suggested that both the PCBMA poymer brush and Ag nanoparticles were capable of improving the hydrophilicity, antifouling resistance of protein and bacterial. After the formation of Ag self-assembled PCBMA immobilized layer, the improvement at these aspects was even more obvious. Surface hydrophilicity of membrane was been substantially improved, the initial contact angle dropped by about 57° compared with the pure membrane, up to 33.97°. Membrane obtained a good antifouling property, FRR can reach 93.32%, Rir can be reduced 71%. Membrane also has good resistance to bacterial contamination, which can effectively inhibit the growth of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli).(3) PVDF-g-PCBMA/TiO2 nanocomposite membrane was prepared by the surface grafting-self-assembly method and systematic studies conducted to investigate the effect of combining PCBMA and TiO2 on the membrane hydrophilicity and antifouling resistance of protein and bacterial. The hydrophilicity of PVDF membranes were significantly improved with the increasing loaded degree of TiO2 and the minimum contact angle reached 19.21°bout dropped by 60.79° than the pure PVDF membrane. Moreover, the modified membranes showed a superior and water absorption as the powerful capillary action after numerous TiO2 self-assembled on membranes surface. Additional, the TiO2 loaded membranes possessed a more pronounced enhanced on the water flux recovery ratio and BSA rejection ratio. The study demonstrated that the combination of CBMA and TiO2 imparts superior hydrophilicity and anti-pollution performance to PVDF membrane.