Cross-linked anion exchange membranes with hydrophobic side-chains for anion separation

In this work, high performance cross-linked anion exchange membranes with hydrophobic side-chains were prepared via quaternization reaction and a simple heat treatment. The cross-linked membrane structure, the hydrophobic side-chain and the micro-phase separated morphology of membranes have synergistic effect on ion selective separation. Accordingly, the obtained membranes possess excellent ion perm-selectivity and considerable OH− flux. Especially, QPPO-C6-120 membrane exhibits the superior perm-selectivity of 76 for OH−/WO42− system and high OH− flux of 2.72 × 10−7 mol cm−2 s−1 at a current density of 30 mA cm−2. XPS and 1H NMR confirmed the introduction of long side-chain and the thermo-crosslinking reaction. Meanwhile, the microstructure of membranes was investigated by XRD and SAXS. More importantly, a new perspective of mesoscales by combining the molecule structure with the microstructure of membranes is innovatively used to explore the ion separation mechanism.