Polyfluorene/Poly(vinylbenzyl chloride) Cross-Linked Anion-Exchange Membranes with Multiple Cations for Fuel Cell Applications

An ideal anion-exchange membrane (AEM) must possess good dimensional stability, excellent alkaline stability, and good ionic conductivity. In this study, polyfluorene/poly(vinylbenzyl chloride) (PVBC) cross-linked AEMs with multiple cations are prepared. A cross-linked structure is introduced to enhance the mechanical strength (>30 MPa) and dimensional stability (swelling ratio < 15%) of these AEMs. All PHFxTP100–x–PVBC- and PMFxTP100–x–PVBC-based AEMs exhibit excellent alkaline stability after treating with 2 M KOH at 80 °C for 30 days, which is attributed to the ether-free backbone and cross-linked structure. The long hydrophobic alkyl side chains of PHF10TP90–PVBC favors the construction of microphase separation within the membrane, leading to higher conductivity and cell performance (64.56 mS cm–1 and 323 mW cm–2, at 80 °C) than those of the PMF10TP90–PVBC (57.56 mS cm–1 and 100 mW cm–2 at 80 °C). The results indicate that polyfluorene/PVBC cross-linked AEMs with multiple cations are prospective membrane materials for fuel cells.