Sulfonated Aromatic Polyethers Containing Pyridine Units as Electrolytes for High Temperature Fuel Cells

Novel sulfonated copolymers bearing main chain pyridine units have been synthesized for use as electrolytes in high temperature proton exchange membrane fuel cells (PEMFCs). The aim was to combine the excellent thermomechanical properties and high conductivity values after doping with phosphoric acid of these materials with the ability of the sulfonic groups to absorb and retain water and finally to examine the effect on the proton conduction ability. The resulted copolymers showed excellent film forming properties, mechanical integrity, and high glass transition temperatures (T-g > 300 degrees C). The T-g of the sulfonated copolymers is strongly affected by the sulfonated group content in the polymer backbone due to the acid base interactions of the pyridine and sulfonated groups. Furthermore, the membranes exhibited remarkable oxidative stability and presented proton conductivities in the range of 10(-2) S cm(-1).