A novel anion exchange membrane based on silicone/polyphenylene oxide with excellent ionic conductivity for AEMFC

Abstract To achieve good stability of anion‐exchange membranes. We report an organic–inorganic composite anion exchange membrane based on polyphenylene oxide (PPO) and 3‐[2‐(2‐aminoethylamino)ethylamino]propyl‐trimethoxysilane to improve dimensional stability and mechanical stability without affecting ionic conductivity. The successful synthesis of the membranes was confirmed by FT‐IR, 1 H NMR, and EDX. The SiOSi three‐dimensional network cross‐linked structure was formed inside the anion‐exchange membranes by added inorganic fillers. It suppressed the swelling behavior of the membrane after water uptake, with water uptake rate of 48.2%–55.6% and swelling rate of 3.1%–14.2%. It improved the mechanical strength of the membranes with tensile strength of 33.5–37.8 MPa as the ratio of the membrane structure varied. Meanwhile, the flexible chain segments in the polymer structure contributed to the formation of microscopic phase separation structures, and the constructed ion‐conducting channels enabled QPPO‐Si‐5 to reach the highest hydroxide ion conductivity of 78.7 mS/cm at 80°C (ion exchange capacity [IEC] value of 1.2 mmol/g). QPPO‐Si‐1 exhibited better long‐term chemical stability, retaining 48.3% of the initial conductivity (30.8 mS/cm) after 600 h of alkali stability testing at 80°C in 1 M KOH solution. In conclusion, the results of this study provide a facile synthetic strategy with improved membrane's comprehensive performance.