Neutron and x-ray scattering: Suitable tools for studying ionomer membranes

Nafion (R) to interpret not only the numerous scattering data Neutrons and x-rays were extensively used to study the microstructure of the polymeric membranes for fuel cells. The small-angle x-ray and neutron scattering (SAXS and SANS resp.) data for Nation (R) and alternative membranes present specific features. The different analyses and proposed models to interpret these data are reviewed. A special emphasis is devoted to the recent elongated polymer particle model which appears as the most efficient model for but also the transport swelling and mechanical properties. Neutrons can also be used to study the water management in situ in an operating fuel cell either to visualise the water accumulation in the gas distributors or to determine the water concentration profiles through the membrane and during operation.