Preparation and Characterization of Non-N-Bonded Side-Chain Anion Exchange Membranes Based on Poly(2,6-dimethyl-1,4-phenylene oxide)

Due to the polyether structure on the main chain, the alkali resistance of quaternized poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) anion exchange membranes (AEMs) needs to be improved. Through the Williamson etherification reaction, we synthesized a new type of PPO-based AEM with a quaternized piperidine cation side chain, which has good ionic conductivity (63.5 mS cm–1 at 80 °C). Due to being non-N-bonded, it has good alkali resistance, and the conductivity loss is less than 10% when immersed in 1 mol L–1 KOH solution for 480 h. In addition, we also prepared other two AEMs (N-bonded) for comparison and studied their degradation mechanism by Fourier transform infrared spectroscopy. The study found that the non-N-bonded PPO-based AEM has the lowest OH– conductivity loss and its C–N retention is the highest after soaking in alkali, which shows that the non-N bond and the ether bond can effectively improve alkali resistance, while the conductivity is not lower than that of the AEM with N-bonded cations.