Facile Preparation of an Ether-Free Anion Exchange Membrane with Pendant Cyclic Quaternary Ammonium Groups

Ether-bond-free polyfluorene (PBF) anion exchange membranes (AEMs) containing flexible alkyl pendent chains terminated with piperidinium cations were prepared via one-pot, superacid-catalyzed polycondensation and a subsequent quaternization reaction. Hydrophilic and hydrophobic microphase segregation was observed in all AEMs. The hydroxide conductivity of PBF2-Br reaches up to 86 mS cm-1 at 80 °C, and 1H NMR showed no measurable degradation after alkaline treatment in aqueous NaOH (1 M) solution for 1200 h at 80 °C. Besides, a peak power density of 410 mW cm-2 was achieved at 60 °C for an alkaline fuel cell using the selected PBF1-OH (OH- form) as AEM.