Poly(phthalazinone ether sulfone) and Polythiophenequinoxaline as High Temperature Proton Exchange Membranes (PEMs) for Hydrogen and Methanol Fuel Cells

Abstract

Highly aromatic polymers, poly(phthalazinone ether sulfone) (PPES) and polythiophenequinoxaline (PTQx), have been developed due to their high glass transition temperature (Tg). Both PPES and PTQx were tested for their molecular weight using size exclusion chromatography. Two approaches were used to synthesize the sulfonated poly(phthalazinone ether sulfone). The first was post sulfonation of the synthesized polymer and the second was polymerization of the sulfonated starting monomers. A blend membrane of sulfonated poly(ether sulfone) (SPES) and SPPES was made and characterized for its ion exchange capacity and conductivity. The glass transition temperature measurement was also carried out for both SPES:SPPES blend membrane and PTQx. The post sulfonation method has a much lower yield of 5.99% compared to 79.2% yield when polymerization of sulfonated monomers is done. The SPES:SPPES blend membrane glass transition temperature was found to be 164 °C. Its conductivity and ion exchange capacity was found to be 0.010 S/cm and 0.32 meq/g respectively.