Sulfonated polyimides: Synthesis, proton conductivity and water stability

Six-membered ring sulfonated polyimides (SPIs) are promising membrane materials for low temperature (<100 °C) fuel cell application. This paper describes our recent work on the synthesis of various sulfonated diamine monomers and the related sulfonated polyimides. The relationship between the chemical structure and the proton conductivity and water stability of various sulfonated polyimide membranes is discussed in detail.