表面“原位”聚离子复合修饰的乙烯-乙烯醇共聚物膜的结构

聚离子复合物(Polyionic complexes,PICs)是由聚正离子和聚负离子所构成的高度亲水的合成材料,可以通过不同聚离子的组合使其带有"净"电荷.因此,它具有优良的血液相容性.PIC透析膜对小分子电解质和低分子物质有很高的透过性1],然而,在高含水状态下PIC离子键的水合使其强度明显降低,并且由于其只溶于一定组成的三组份屏蔽溶剂(Shielding solvent),因此,给加工制膜带来诸多不便.乙烯-乙烯醇共聚物(Ethylene-vinyl alcohol copolymer,EVAL)表现出一定的亲水性,并且高分子链中含疏水性链段,有一定的机械强度,是一种性能很好的成膜材料,由EVAL制成的膜已应用于血液过滤等领域2].

STRUCTURE OF SURFACE-MODIFIED ETHYLENE-VINYL ALCOHOL COPOLYMER MEMBRANE BY IN SITU POLYIONIC COMPLEXATION

An EVAl membrane with polyionic complex (PIC) as a skin layer has been prepared by in situ polyionic complexation between the cationically modified surface of EVAl membrane and the corresponding polyanion solutions.Two types of polyanions like sulfonated EVAl and phosphorylated EVAl,as well as quaternary ammonium modified EVAl membrane were synthesized and used for polyionic complexation.To reach the complete complexation,the amount of polyanion must be well above the cations on the surface of EVAl.The x ray photoelectron spectroscopy and elemental analysis revealed that the complexation mainly occurred on the surface of EVAl membrane.An asymmetric membrane with more condensed skin layer and porous inner layer was obtained,which may find new applications in biological field.