Applications of acid base blend concepts to intermediate temperature membranes

Abstract

In this chapter, an overview is given about the scientific work done so far in the synthesis, characterization, and fuel cell application of acid-base blends from different polybenzimidazoles as the major blend component and different kinds of acidic polymers such as sulfonated and phosphonated polymers as the minor blend component. In these blends, ionical cross-links are formed by proton transfer from the acidic group to the polybenzimidazole imidazole-N, forming ionical cross-links by the electrostatic interaction between the acidic anions and the imidazolium cations, which leads to improvement of mechanical and chemical membrane stability, compared to pure polybenzimidazoles. The chapter is concluded by a short comparative study between differently cross-linked polybenzimidazoles in terms of their properties such as thermal stability, stability in Fenton’s Reagent, and proton conductivity when doped with phosphoric acid. The outcome of this study was that the properties of all the different polybenzimidazole blends were quite similar.