Synthesis of alkaline anion exchange membranes (AAEMs) for fuel cell and metal-air battery applications
Most current AAEMs are processed by the chloromethylation–quaternization of a pre-existing polymer precursor, which compromises the conductivity and mechanical properties of the polymer. Our group synthesized AAEMs using a bottom-up approach through copolymerizing various monomers that were intentionally selected to fulfill the AAEM's conductive and mechanical requirements. In the poly- [(methyl methacrylate)-co-(butyl acrylate)- co-(vinylbenzyl chloride)] (PMBV) copolymer, methyl methacrylate (MMA) is the hydrophobic part of the polymer chain that provides mechanical support. Butyl acrylate (BA) is a hydrophobic portion with a lower glass transition temperature (Tg) than MMA that allows for the flexibility of the polymer chain. Vinylbenzyl chloride (VBC) is the functional group that can be quaternized and ion-exchanged to provide conductivity. The obtained AAEM demonstrated superior alkaline fuel cell performance: 180 mW cm-2 peak power density at 70oC. The unique contribution of this research is that a bottom-up miniemulsion polymerization was employed to synthesize an alkaline polymer electrolyte. This work was published in ChemSusChem, J. Power Sources, and in Macromolecular Chemistry & Physics.