Anion-exchange membranes (AEMs) have widespread applications in electrochemical devices. The development of AEMs with long-term alkaline stability and high hydroxide ion conductivity is currently of interest. The use of non-precious catalysts, facile reaction kinetics and reduced fuel crossover are some of the benefits over proton-exchange membranes (PEMs). However, the present limitations of AEMs include low ionic conductivity, poor stability at high pH, and high water uptake.

A series of multiblock copolymers based on vinyl addition and ring-opening metathesis polymerization (ROMP) of norbornenes was synthesized for use in AEM fuel cells and electrolyzers (Scheme 1). The mechanical and thermal stability, ionic conductivity of both sets of polymers are discussed in detail. The long-term (>1200 h) alkaline stability results are promising.

Financial support provided by the ARPA-E IONICS program for M.M. and G.H. is gratefully acknowledged.