Sulfonated Polyimides

Sulfonated polyimides have been designed to be used as proton conducting membranes in fuel cells. These materials present most of the required properties for this application, including a high level of ionic conductivity, a low gas and methanol permeability, and good mechanical properties. However, they exhibit a low stability when immersed in liquid water and in hydrogen peroxide solutions at elevated temperature due to a high sensitivity of the imide functions to hydrolysis. The aim of this article is to review the different routes of synthesis, the membrane-specific properties, the structural and transport property characteristics, and finally their behavior in fuel cells in terms of performance and stability.