Multiblock copolymers with locally high ionic concentration for anion exchange membranes

With the use of alkaline membrane fuel cells (AMFCs) there is a possibility to utilize low temperature fuel cell technology without the need of scarce and expensive noble metal catalysts. With this technology there is, however, a need to enhance the stability and ionic conductivity of anion-exchange membranes (AEMs) before AMFCs can be a viable alternative to the more studied proton-exchange membrane fuel cells. In the presented work we have aimed to improve the anionic conductivity by synthesizing multiblock copolymers containing blocks with exceptionally high local ion exchange capacity (IEC). Thus, a series of AEMs, based on poly(arylene ether sulfone)s, with IECs in the hydrophilic domain in the range between 4.9 and 5.8 meq./g has been produced. The high IEC was achieved by incorporating tri- and tetramethylhydroquinone into the polymer backbone, thus enabling the attachment of three and four ionic groups respectively on single aromatic rings. The structure− morphology− property relationships and the performance of these copolymers and AEMs will be presented.