| In recent years, as novel power supply devices, alkaline anion exchange membrane fuel cells (AAEMFCs) have gradually become hot research topic in the field of fuel cells. They have several benifits upon proton exchange membrane fuel cells (PEMFCs), containing more options to use non-noble metals such as Fe. Anion exchange membrane (AEM)-one of the core parts of the AAEMFCs, is the critical factor to decide the alkaline anion exchange membrane fuel cells’efficiency and life. The ideal AEM should meet the requirements of high ionic conductivity, excellent mechanical property, outstanding thermal stability, and long-term alkaline stability. So far, due to their low ionic conductivity and poor chemical alkaline stability, commercial AEMs still cannot satisfy the demands of AAEMFCs.As the matrix, poly(ether ether ketone) (PEEK) a type of aromatic semicrystalline thermoplastic high performance commercial polymer material has good performances including high chemical stability and good thermal stability. The inorganic zirconium dioxide (ZrO2) nanoparticle material has large specific surface area, superior hydrophilic and mechanical properties. Currently one of the major puzzles for the fuel cells is the poor alkaline stabilities. In order to improve the alkaline stabilities, in this dissertation, we made an attempt to disperse the inorganic nanosized ZrO2 fillers into the novel imidazolium-functionalized poly(ether ether ketone) (PEEK) matrix. The introduction of hydrophilic nanosized ZrO2 fillers will result in the formation of the solvation effect to the OH- ions, further making the alkaline stabilities enhancing. The possible mechanism was that the nanosized ZrO2 incremented the water uptake of the membrane, thus having a dilution effect to the OH- ions. The lower concentration of alkali implied that the hydroxy hydration degree was higher and the hydroxyl was surrounded by large amount of water; Meanwhile, the high water uptake of the membrane also had protection effect to the ion exchange group, thus reducing the OH- ion’s attack and improving the alkaline stabilities.Using low volatility and toxicity chloromethyl octyl ether (CMOE) as chloromethylation reagent,98% concentrated sulphuric acid as solvent and catalyst. In this paper CMPEEK was successfully synthesized. Reaction under low temperature, e.g.-10℃, was required for the good controllability of chloromethylation degree (DC) of CMPEEK. The appropriate reactants’proportion were M (PEEK):V (H2SO4):V (CMOE)=1 g:60 mL:20 mL, the reasonable reaction temperature was -10℃, CMPEEKs with different DC were successfully prepared by changing the reaction time. The solubility experiment manifested that CMPEEKs with different DC exhibited excellent solubility in high boiling casting membrane solvents.The PEEK-ImOH/ZrO2 composite alkaline anion exchange membranes were carried out via blending method with CMPEEK as matrix,1,2-dimethylimidazole for imidazole reagent. The nanoparticle content was separately 0%,2.5%,5%,7.5%,10%(CMPEEK-x%ZrO2). The morphology of the composite organic-inorganic membranes was examined by SEM. The X-ray diffraction was scanned to reveal the crystallinity of the composite membranes. It could be seen in the TGA curves that the mixture of ZrO2 heightened the composite membranes’ thermal stability. The water uptake of the composite membranes increased with enhancing amount of ZrO2. The composite membrane containing 7.5%ZrO2 had the highest water uptake (25.27%,20℃), and also exhibited the highest conductivity (53.96 mS/cm,80℃), but with the lower swelling ratio (12.45%,20℃), the best alkaline stability (3 M NaOH treated 24 h, the conductivity declining 4.27%).This thesis had succeeded in synthesizing organic/inorganic composite alkaline anion exchange membranes with high alkali resistance, which will have potential applications in fuel cells. |
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