Methods for modifying proton exchange membranes using the sol–gel process

Over the past 20 years, sol–gel processing has expanded into organic–inorganic hybrid materials. This expansion has benefited from the collaborations between the polymers community and the ceramics community, and the discovery that in many instances sol–gel processing and polymer processing are compatible. An active participant in this field has been Dr James E. Mark [Mark JE. Heterog Chem Rev 1996;3:307–320], and his accomplishments deserve this tribute. One example, which derives from his work in organically-modified silicates (ORMOSILS), is hybrid membranes for fuel cells. We present some recent progress in synthesis of hybrid membranes involving Nafion. These membranes have been prepared by infiltration and recasting, and contain silicates, phosphosilicates, zirconium phosphosilicates and titanosilicates.