Abstract
Sulfonated poly(ether ether ketone) (SPEEK) membranes were thermally treated at temperatures between 120 and 160 °C. Water uptake measured at different relative humidity values or by full immersion in water between 25 and 145 °C was found to depend very strongly on previous thermal treatment and casting solvent. Water-uptake coefficient values as low as 10−15 even upon immersion in water at 100 °C were obtained with membranes treated at 160 °C. This effect is related to cross-linking by SO2 bridges between macromolecular chains. An important role is also played by the casting solvent: among the investigated solvents, dimethylsulfoxide (DMSO) gave the best results. A chemical kinetics model is outlined that permits the estimation of the relevant kinetic parameters, especially the activation energy of the cross-linking reaction, which was found to be about 60 kJ/mol. These results are of significant importance for the improvement of proton-exchange membrane fuel cells.
Illustrations
Details
Published on: The Journal of Physical Chemistry B 2009, 113, 7505-7512
Authors: M. L. Di Vona, E. Sgreccia, S. Licoccia, G. Alberti, L. Tortet, P. Knauth