PVDF/PAA-b-PMMA-b-PAA超滤膜的结构调控和性能评价

Structural regulation and performance evaluation of PVDF/PAA-b-PMMA-b-PAA ultrafiltration membrane

采用可逆加成-断裂链转移自由基聚合(RAFT)合成了以聚丙烯酸(PAA)为亲水链段和聚甲基丙烯酸甲酯(PMMA)为疏水链段的两亲性三嵌段共聚物PAA-b-PMMA-b-PAA(PAMA),通过傅里叶变换红外光谱(FTIR)和核磁共振氢谱(~1HNMR)对聚合物进行了化学结构表征.然后以聚偏氟乙烯(PVDF)为成膜物质,PAMA为改性剂,利用非溶剂诱导相转化法制备了一系列PVDF/PAMA共混超滤膜.研究了PAMA含量对PVDF/PAMA膜的表面化学结构、微观形貌、亲水性、渗透性能以及抗污性能的影响.结果表明,当共混膜中PAMA含量增大时,PVDF/PAMA膜的表面孔密度、孔径和粗糙度均呈现不断增大的趋势.当共混膜中PAMA质量分数为18.2%时,纯水通量由未改性的PVDF膜的12.9 L/(m^2·h)增大至130.2 L/(m^2·h),BSA截留率为97.2%,通量恢复率高达97.5%.因此,PVDF/PAMA共混超滤膜的渗透性能和抗污性能有明显提高.

A kind of well-defined amphiphilic block copolymer of poly(acrylic acid)-b-poly(methyl methacrylate)-b-poly(acrylic acid)(PAA-b-PMMA-b-PAA, termed as PAMA) was prepared by RAFT polymerization using PAA as hydrophilic chains and PMMA as hydrophobic chains. The chemical structures of PAMA were characterized by fourier transfer infrared spectroscopy(FTIR) and proton nuclear magnetic resonance(~1HNMR). Subsequently, a series of PVDF/PAMA blended ultrafiltration membranes were prepared by non-solvent induced phase inversion method using poly(vinylidene fluoride)(PVDF) as the membrane-forming substances and PAMA as the blending modifiers. The effect of modifier content of PAMA on the surface chemical structure, morphology, hydrophilicity, permeability and antifouling properties of the blended membranes were investigated. The results demonstrated that the surface pore density, pore size and roughness of the modified ultrafiltration membranes showed an increasing trend when the concentration of PAMA in the blend membrane increased. When the modifier concentration was 18.2%, the membrane flux increased from 12.9 L/(m^2·h) for the unmodified PVDF membrane to 130.2 L/(m^2·h) for PVDF/PAMA membrane, and the flux recovery rate was as high as 97.5%. Therefore, PVDF/PAMA membrane showed improved permeation and excellent antifouling properties.