Towards the gemini cation anion exchange membranes by nucleophilic substitution reaction

As a critical component of alkaline fuel cells, anion exchange membranes determine the energy efficiency, output power density and the long term stability. Recently, the anion exchange membranes with gemini-cation side chains exhibit superior ion conductivity due to their good nano-phase separation. However, the costly and complicated synthesis limits their scaling up and commercialization. To address this problem, a convenient synthetic procedure under mild conditions is well developed. A tertiary amine precursor is introduced onto the polymer by the nucleophilic substitution reaction to avoid the conventional chloro/bromo-methylation. Followed by a simple Menshutkin reaction with 6-bromo-N,N,N-trimethylhexan-1-aminium bromide, the polymer electrolytes are obtained in a high yield. The resulting anion exchange membranes with high conductivity, good fuel cell performance and restricted swelling suggest the potential for the application in fuel cell devices.