Multiply quaternized poly(phenylene oxide)s bearing β-cyclodextrin pendants as assisting moiety for high-performance anion exchange membranes

A bulky and hydrophilic beta-cyclodextrin group, serving as a performance assisting moiety , was grafted onto a poly(phenylene oxide) (PPO) to achieve a new family of polymer electrolytes with different kinds of quaternary ammonium salts (QAs) for anion exchange membranes (AEMs). It was observed that the beta-cyclodextrin involved AEMs having a well-designed molecular architecture exhibited some attractive properties. At the same ion ex-change capacity level, the highest conductivity at 80 C of the cyclodextrin-involved anion exchange membranes reached 110.8 mS cm-1, which was almost twice as high as that of a reference membrane. As a novel assisting moiety , the incorporation of the functional cyclodextrin groups also endowed membranes with suitable water uptakes of 60.2-93.8% and swelling ratios of 11.5-22.8% at 80 C. A comparative study revealed that the cyclodextrin-involved membranes had an improved alkaline stability and a satisfactory cell performance. The maximum power density of one cyclodextrin-based membrane was 154 mW cm-2, which was three folds higher than that of the analogue without assisting moiety . In general, this study offers an effective synthetic strategy to prepare the high-performance anion exchange membranes with an excellent combination of high conductivity, low swelling, good alkaline stability and reasonable cell performance.

Automated summary

By grafting bulky and hydrophilic beta-cyclodextrin onto a poly(phenylene oxide), a new family of high-performance polymer electrolytes for anion exchange membranes was developed. These membranes exhibited higher conductivity, suitable water uptake and swelling ratio, improved alkaline stability, and better cell performance compared to reference membranes. The incorporation of functional cyclodextrin groups also led to a threefold increase in power density, demonstrating an effective synthetic strategy for preparing high-performance anion exchange membranes.