聚氯乙烯-聚丙烯酸嵌段共聚物改性的pH响应性聚氯乙烯超滤膜

pH-Responsive Poly(vinyl chloride) Ultrafiltration Membranes Modified by Poly(vinyl chloride)-Poly(acrylic acid) Block Copolymers

为了改进聚氯乙烯(PVC)超滤膜的渗透和抗生物污染特性,采用单电子转移-蜕化转移活性自由基聚合制备了聚丙烯酸-b-聚氯乙烯-b-聚丙烯酸三嵌段共聚物(PAA-b-PVC-b-PAA),并采用非溶剂诱导相转移法制备了PAA-b-PVC-b-PAA改性的PVC超滤膜。发现PAA-b-PVC-b-PAA具有微相分离特性,对应PVC和PAA嵌段的玻璃化温度分别为80和108oC。PAA-b-PVC-b-PAA的引入使膜的指状结构增大。由于PAA-b-PVC-b-PAA共聚物在膜表面的富集,共混物超滤膜的水通量随着PAA链长的增长而增大。随着pH值变化,PAA链段的荷电性和构象变化,使共混物超滤膜的渗透行为具有可逆pH响应性,pH值由2.3增大到11.6时,水通量明显下降;在强酸性和碱性条件下,PAA链段与牛血清蛋白存在强的电荷排斥作用,通量和抗污染性较好。

In order to improve permeation and antifouling properties of poly(vinyl chloride)ultrafiltrationmembranes,poly(acrylic acid)-b-poly(vinyl chloride)-b-poly(acrylic acid)triblock copolymers(PAA-b-PVC-b-PAA)were synthesized by single electron transfer-degenerative transfer living radicalpolymerization,and blended with PVC to fabricate ultrafiltration membranes by a non-solvent induced phaseseparation method.It is found that the PAA-b-PVC-b-PAA copolymer shows micro-phase separation with twoglass transition temperatures corresponding to PVC and PAA blocks,respectively.The addition ofPAA-b-PVC-b-PAA copolymer results in the formation of membranes with big tunnels.Water fluxes increasewith the increase of PAA chain length due to the enrichment of PAA chains in the membrane surface.Theblend membranes exhibit pH-responsive water flux as the conformation of PAA chain varies with water pH.Moreover,the blend membranes show greater bovine serum albumin(BSA)solution flux and better antifoulingproperties under strong acidic and basic conditions due to electrostatic repulsion between BSA and PAA.