耐压型聚砜两亲嵌段共聚物超滤膜的制备与表征

Preparation and characterization of pressure-resistant polysulfone-based amphiphilic block copolymer ultrafiltration membranes

聚砜类分离膜广泛应用于超滤过程并作为支撑层用于纳滤膜及反渗透膜的制备,然而由于材料自身的疏水性较强,聚砜膜通常要经过亲水化改性来提升渗透和抗污染性能.以两亲嵌段共聚物聚砜-b-聚乙二醇(PSf-b-PEG)为原料,通过相转化法可无需后期改性制备具有指状孔结构的自发永久亲水性超滤膜,但指状孔的存在使其耐压性能受到限制,难以用作纳滤或反渗透膜的支撑层.采用PSf-b-PEG为制膜材料,通过调节固含量与非溶剂诱导相分离过程中的溶剂/非溶剂体系,将超滤膜断面的指状孔转变为更耐压的海绵状孔,同时在膜内保留亲水链段以保证膜的渗透性及抗污染性能.研究结果表明,当以N,N-二甲基甲酰胺(DMF)为溶剂,去离子水为凝固浴时,可直接制备出具有海绵状孔结构的PSf-b-PEG超滤膜.在25%的固含量下,膜的纯水渗透性为1 600L/(m^2·h·MPa),对牛血清白蛋白(BSA)截留率达到90%.压密测试表明,相较于指状孔,海绵状孔超滤膜可完全耐受1 MPa的压力,展示了更优的耐压性能.

Polysulfone membranes are widely used as ultrafiltration membranes and the support layers for composite membranes.However,due to the strong hydrophobicity of the material itself,polysulfone ultrafiltration membranes need some modifications to enhance their penetration and anti-fouling performance.We have previously prepared permanently hydrophilic ultrafiltration membranes with fingerlike pores by using amphiphilic block copolymer PSf-b-PEG.In this work,we try to prepare sponge-like membranes with the same material by changing the solvent/nonsolvent system and the concentration of the polymer solution.The results showed that when N,N-dimethylformamide(DMF)was used as solvent and deionized water was used as nonsolvent,PSf-b-PEG ultrafiltration membranes with sponge-like structure could be directly prepared.The pure water permeance of membranes reached 1 600 L/(m^2·h·MPa)and the rejection of bovine serum albumin(BSA)reached 90% at concentration of 25%.Pressure-resistance tests showed that membranes with the sponge-like structure have superior pressure resistance to that of the finger-like membranes.