Perfluorinated comb-shaped cationic polymer containing long-range ordered main chain for anion exchange membrane

Abstract

Achieving high ionic conductivity and alkaline stability of anion exchange membranes (AEMs) is critical for anion exchange membrane fuel cells (AEMFCs). Here we described a method of preparing perfluorinated comb-shaped cationic polymers containing long-range ordered (LROed) –CF2CF2-(CF2CF2)n–CF2–CF2- main chain with pendant (-CF2CF2SONH-) side chain terminated by long comb-hydrophilic-cationic groups for AEMs application. Super-hydrophobic backbone promoted the formation of defined nano-phase separated channels and the resulted comb-shaped AEMs demonstrated ion conductivity of 88.6 mS cm−1 at 80 °C and kept low water uptake (17.1 wt%) and excellent dimensional stability (7.0%). Chemically robust polymer skeleton reduced hydroxide ion attack at fixed cation group and 91.8% of initial values was retained after Hoffman elimination in 8 M KOH over 16 days at 80 °C. Furthermore, a membrane electrode assembly (MEA) based on perfluorinated-comb AEMs showed a peak power density of 306.1 mW cm−2 at 80 °C in a H2/O2 (CO2-free) fuel cells.