Thermally stable anion-exchange materials

Anion-exchange materials are of great interest in a broad field of applications like water treatment, catalysis or electrochemical devices like electro dialysis or fuel cells. The anion-exchange materials are widely based on (cross-linked) polystyrene functionalized with trimethyl ammonium groups fixed via a methylene bridge to the benzene ring. Nearly all anion-exchange materials have in common, that they are thermally unstable at elevated temperature and high pH. However, in electrochemical applications like fuel cells or in electro dialysis high temperatures are desired for competitive performances. In a recent study Marino and Kreuer1 investigated the thermal stability of quaternary ammonium model compounds. Among the various compounds those based on piperidine (Fig. 1) turned out to be most stable ones. Pham and Jannasch2 reported on polymeric anion-exchange materials based on poly(ether sulfone)s bearing N-spirocyclic quaternary ammonium groups similar to those reported by Marino and Kreuer. However, these polymers showed only a low thermal stability. Please click Additional Files below to see the full abstract