Preparation And Characterization Of New Functional Organic-Inorganic Hybrid Ion Channel Membrane

Five kinds of organic-inorganic hybrid functional materials were prepared from isocyanate silane and aromatic amine compounds with benzene ring or amino amyl alcohol compound without benzene ring. The structure and the crystallinity of the functional materials were characterized by FT-IR,"H-NMR, XRPD, single-crystal XRD and DSC methods. According to the self-assembling property of the materials, the organic-inorganic hybrid ion channel membranes were obtained by blending the materials and polymer through sol-gel process using spin-coating method. The structure of the membranes was characterized by SEM and TEM. Next, the transport performance of the membranes was evaluated by competitive ion transport experiments and I-V curves, and the ion transport mechanism of this new functional organic-inorganic hybrid ion channel membrane was proposed. The effects of different aromatic groups, hydrophobic/hydrophilic polymers and the content of the membrane materials on the ion transport properties were studied. In addition, the application of the membrane in all vanadium redox flow battery was investigated preliminarily.The results of FT-1R and H NMR showed that the structures of five kinds of functional materials—3-(ureidobenzene)propyltriethoxysilane(H1),3-(ureido-4-methoxyphenyl)propyltriethoxysilane(H2),3-(ureido-3-chloro-4-methoxyphenyl)propyltriethoxysilane(H3),3-(ureidoindazolyI)propyltrieth-oxysilane(H4) and3-(ureidopentanol)propyltriethoxysilane(H5) were consistent with the target products. XRD demonstrated that the functional materials had good crystalline and could form regular structures by self-assembly.SEM images revealed that the organic-inorganic hybrid ion channel membranes were dense without micropinholes. The thickness of the membranes were around30-50μm from the SEM images of cross section. Then five kinds of cations (Li+, Na+, K+, Ca2+and Mg2+) were chosen for membrane transport experiments. The results demonstrated that the functional materials with different benzene ring (H1-H4) transported monovalent Li+, Na+and K+except Ca2+and Mg2+. The order of the ion transport properties of four kinds of functional materials (H1-H4) was as follows:H2>H1>H4>H3, and the permeability of Li+, Na+and K+transporting through the hybrid membranes followed the order PNa+> Pk+>PLi+.While the fuctional material of H5without aromatic rings has poor transport performance for Li+, Na+and K+and could not transpot Ca2+and Mg2+The effect of hydrophobic/hydrophilic polymers on the ion transport properties was studied. The results of the permeability showed that hydrophobic PVDF-based ion channel membrane had better transport performance than that of hydrophilic PVA-based membrane.The proportion of the functional material and PVDF had influence on the ion selectivity of membrane. The result demnonstrated that the ion transport property was improved when the content of the functional material increased. When the mass ratio of H2and PVDF was10:15, the Na+permeability of ion channel membrane M3was twice more than Li+or K+. It revealed that H2was well selective for Na+. The results of Ⅰ-Ⅴ curves showed that NH4+could not transport through H2. And H2had various selectivity for different anions, as:Cl->NO3->HCO3->SO42-, suggesting that H2was well selective for CT.This new functional organic-inorganic hybrid ion channel membrane was applied to the separator for all vanadium redox flow batteries. The ionic conductivity and the water uptake of ion channel M3were1.73×10-3S·m-1and2.45%respectively. M3had low permeability of VO2+, and the H/V selectivity of M3was16.6. This kind of ion channel membrane will have significant application in the separator for all vanadium redox flow batteries.