(142at) Polyimide-Polysiloxane Segmented Copolymers for Fuel Cell Applications

Sulfonated perfluoropolymers (e.g. Nafion) are currently used in fuel cell applications due to their high proton conductivity, chemical resistance, and mechanical stability. There is great demand to develop less expensive non-fluorinated polymers that exhibit equally high performance. We are developing nanostructured aromatic polyimides as an approach to fulfill this need. Polyimides have high strength, film-forming ability, superior chemical resistance, and can easily be sulfonated. Here we report on the one-pot synthesis and characterization of sulfonated polyimide-polysiloxane segmented copolymers. This approach enables tuning of both the siloxane content and the degree of sulfonation. The resulting material is soluble in selective solvents and can be solvent-cast into free standing films. The siloxane content significantly improves the adhesion of membranes onto glass. Our present focus is to understand the interrelationship between proton conductivity, ionic content, and morphology in these copolymers.