Synthesis And Study Of Sulfonated Poly(Ether Ether Ketone Ketone)s Proton Exchange Membranes

Proton exchange membrane fuel cells (PEMFC) are devices that directlyconvert the chemical energy of reactants (fuels and oxidants) into electricity viaelectrochemical reactions. PEMFC as the rapidly developing fifth-generation fuelcell have received widely investigated as a promising new power sources forvehicles and portable devices, due to their low emissions and high conversionefficiency.The proton-exchange membrane is the core component of PEMFC. It differsfrom the membranes used in chemical cells in that it not only acts as an insulatorbetween the fuel and the oxidant, but also works as an electrolyte. At present, theonly available commercial products of proton-exchange membrane are the Nafionseries of perflurosulfonic acid membranes from Dupont. Nafion has good chemicaland physical properties for use in fuel cell fields. But it has three major drawbacks,including low conductivity at low humidity or high temperature, as well as highmethanol permeability. Thus new polymer electrolyte membranes for fuel cell arebeing explored. Poly(aryl ether ketone)s which have good thermal stabilities andhigh performance have been widely investigated for proton exchange membranesfuel cell materials.We have successfully prepared SPEEKK polymers with different sulfonateddegrees by directly polymerization of sulfonated monomers. Further we havecharacterized the structures in detail. The results showed that: the direct-sulfonationmethod is a powerful method to prepare SPEEKK polymers moreover this methodcan avoid the cross-linking and other side reactions. We have studied the propertiesof the resulted SPEEKK membranes in detail. The properties mainly include wateruptake, ion exchange capacity and proton conductivity.