自组装杂化离子通道膜的构筑及阳离子传输机制

以3-异氰酸丙基三乙氧基硅烷和对甲氧基苯胺为原料合成了一种可以自组装形成有机-无机杂化材料的化合物--3-(脲基-4-甲氧基苯基)丙基三乙氧基硅烷. 采用FT-IR, ¹H NMR, DSC 和XRD 分析方法对该化合物的结构以及结晶性进行了表征. 将该化合物与聚乙烯醇(PVA)共混, 利用化合物的自组装性质构筑结构均一且致密无孔的离子通道杂化膜, 通过自制的膜运输实验装置测定膜对阳离子的传输性能并提出了相应的传输机制. SEM 照片显示, 自组装杂化膜致密无缺陷, 膜厚度为8 μm. 选择5 种阳离子进行运输实验测试, 结果表明, 自组装杂化离子通道膜对一价的碱金属离子Li⁺, Na⁺和K⁺有很好的传输功能, 这要归功于杂化材料中甲氧基苯基与碱金属阳离子形成的阳离子-π相互作用力. 碱金属阳离子在膜中的扩散过程可由溶解-扩散机制来解释, 结果显示, Li⁺, Na⁺和K⁺在杂化膜中传输的渗透率大小为: P_Na⁺ > P_K⁺ > P_Li⁺ , 说明本研究中的的自组装杂化离子通道膜对Na⁺有优先选择性. 杂化离子通道膜对二价的Ca²⁺和Mg²⁺没有传输作用, 此结果给一二价阳离子的分离带来很好的研究思路.

Construction of Self-Organized Hybrid Ion Channel Membrane and Cationic Transport Mechanism

A kind of compound which could form hybrid organic-inorganic mate-rial—3-(ureido-4-methoxyphenyl)propyltriethoxysilane was obtained from 3-isocyanatopropyltriethoxysi-lane and p-anisidine.The structure and the crystallinity of the compound were characterized by FT-IR,1H NMR,DSC,and XRD methods.According to the self-assembling property of the compound,the ion channel hybrid membrane with the homogeneous structure was obtained by blending the compound and polyvinyl alcohol(PVA).Next,the cation transport properties of the membrane were tested by our self-made device,and the transport mechanism was proposed.SEM revealed that the ion channel hybrid membrane was dense and defect free.The thickness of the membrane was 8 μm from the SEM images of cross section.Five kinds of cations were chosen for membrane transport experiments.The results demonstrated that the self-organized hybrid ion channel membrane could transport monovalent Li+,Na+and K+,which was attrib-uted to the cation-π interaction with the methoxyphenyl moiety.The process of alkali cationic transport across membrane was explained with the dissolution-diffusion mechanism.The results showed that the permeability of Li+,Na+and K+transport through the hybrid membrane followed the order PN a+>PK +>PLi+,which revealed that the self-organized hybrid ion channel membrane reported in this paper preferred to transport Na+.Besides the hybrid membrane could not transport divalent Ca2+and Mg2+.The result can provide new membrane materials for the separation of monovalent ions and divalent ions.