用于碱性膜燃料电池的新型聚苯醚阴离子交换膜的制备与性能

以2,6-二甲基聚苯醚(PPO)为原料, 经溴代及N-甲基咪唑季铵化反应, 制备了N-甲基咪唑季铵化PPO, 并进行了红外光谱(FTIR)和氢核磁共振波谱(¹H NMR)表征.所得季铵化产物与聚乙烯醇(PVA)按不同比例共混后用戊二醛交联成膜, 在碱性液中浸泡转化为OH^-型, 得到一系列阴离子交换膜.通过扫描电子显微镜(SEM) 、交流阻抗(AC)、拉伸实验和热重分析(TGA)等手段考察了膜的微观形貌及电导率、力学性能、热稳定性及耐碱性等性能.结果表明, 膜的外观形貌平整均一; 含水率为50.4%~151.2%; 溶胀度为79.2%~164.2%; 离子交换容量为0.47~1.52 mmol/g; 90℃时, M4膜的电导率高达49.1 mS/cm; 断裂伸长率达到128%, 极大改善了PPO膜应力易裂的状况.同时, N-甲基咪唑鎓基团分解温度达到170℃, 高于常用的阴离子交换膜中的季铵基团(120℃).在2 mol/L的NaOH溶液中浸泡192 h后, 电导率仅下降19%, 具备良好的耐碱性能力.

Preparation and Characterization of Novel Poly(2, 6-dimethyl-1, 4-phenylene oxide) Anion-exchange Membranes for Alkaline Fuel Cells

Alkaline anion exchange membrane(AEM) is one of the key materials for anion exchange membrane fuel cells(AEMFC). In this work, starting from poly(2,6-dimethyl-1,4-phenylene oxide)(PPO), the brominated PPO(BrPPO) was synthesized and characterized by FTIR and ¹H NMR spectra. Then an alkaline imidazolium-type resin(PPO-Im) was fabricated via functionalization of BPPO with N-methylimidazole, and the corresponding blending membranes with polyvinylalcohol(PVA) in different content percentages were prepared and characterized by FTIR and ¹H NMR spectra. The SEM images show the prepared membranes are smooth and homogenous. The ion exchange capacity, water uptake, swelling ratio of all prepared membranes were also measured. The ion exchange capacity ranges from 0.47 mmol/g to 1.52 mmol/g. The water uptake is in the range of 50.4%—151.2%. The swelling ratio is in the range of 79.2%—164.2% after being immersed in water at 60℃. The M4 membrane exhibits the highest hydroxide conductivity(49.1 mS/cm at 90℃) by AC-impedance spectroscopy. The tensile strength result shows elongation at break increased to 128%. The thermal gravimetric analyses indicate that the membranes have high thermal stability, which the initial decomposition temperature of imidazolium cation is 170℃, higher than that of quaternary ammonium(120℃). After being immersed in 2 mol/L NaOH for 192 h, the membrane conductivity still keeps their original 81%. All these properties indicate that PPO-Im/PVA membrane is promising for potential applications in alkaline membrane fuel cells.