Graduate student Jason Moore will present “The Effect of POSS functionality on the Properties of Sulfonated Poly(Ether Ether Ketone) for Use in Proton Exchange Membrane Fuel Cells” to the department.
Polymer electrolyte membrane fuel cells (PEMFCs) offer high fuel utilization efficiency and are environmentally benign. Currently, Perfluorosulfonic acid (PFSA) membranes, like Nafion, are the membrane of choice. Nafion possesses key attributes for fuel cell applications such as high proton conductivity and chemical stability. At the same time Nafion has high cost and reduced efficiency at elevated temperatures. The limitations of PFSAs like Nafion have led to a search for alternative membrane materials. One possible candidate is Sulfonated Poly(ether ether ketone) [SPEEK] owing to comparable proton conductivity, superior thermal and chemical properties accompanied with lower fuel crossover. SPEEK also suffers limitations. With a high degree of sulfonation (DS) the long term stability of SPEEK is questionable due to hydroxyl radical initiated degradation. Alternatively, low to medium DS SPEEK exhibits good thermochemical stability but low values of proton conductance. Polyhedral oligomeric silsesquioxane (POSS) can be added to SPEEK in an attempt to reconcile any deficiencies. By functionalizing POSS with various functional groups and adding it to SPEEK polymer it is possible to optimize the component polymer for desirable PEMFC characteristics. The key features optimized for in this study were water uptake, connectivity of water molecules and thus proton conductivity.