Alkaline stable C2-substituted imidazolium-based cross-linked anion exchange membranes for alkaline fuel cell applications

• C2-substituted imidazolium salt was synthesized and used both as crosslinker and hydrophilic phase.
• The imidazolium-based AEMs show the conductivity up to 2.0 × 10−2 S cm−1 at 90 °C.
• The imidazolium-based AEMs show good chemical stability in 1 M KOH solution.

Novel C2-substituted imidazolium-based cross-linked anion exchange membranes (AEMs) are prepared via irradiation with ultraviolet light cross-linking of styrene, acrylonitrile and 1,3-diallyl-2-methyl imidazolium bromine ([DAMIm][Br]), and followed by anion exchange with hydroxide ions. [DAMIm][Br] is synthesized and used both as crosslinker and hydrophilic phase. The ionic conductivity of the AEMs increases with increasing [DAMIm][Br] content due to the hydrophilic regions and the continuous hydrophilic polymeric networks formed in the membranes. The imidazolium-based cross-linked AEMs show excellent thermal stabilities, and the membrane which containing 30% mass fraction of [DAMIm][Br] shows ionic conductivity up to 2.0 × 10−2 S cm−1 and good long-term chemical stability in 1 M KOH solution. The results of this study suggest that the C2-substituted imidazolium-based cross-linked AEMs have good perspectives for alkaline fuel cell applications.