The reaction product of a monomer comprising phthalazinone and a phenol group, and at least one sulfonated aromatic compound. The monomer comprising phthalazinone and a phenol group is used in a reaction with the sulfonated aromatic compound to produce ionomers with surprising and highly desirable properties. In one embodiment, the inventive ionomer is a sulfonated poly(phthalazinone ether ketone), hereinafter referred to as sPPEK. In another embodiment, the inventive ionomer is a sulfonated poly(phthalazinone either sulfone), herein after referred to as SPPES. In another embodiment, the inventive ionomer is other sulfonated aromatic polymeric compounds. The invention further includes the formation of these polymers into membranes and their use for polymer electrolyte membrane fuel cells (PEMFC), and in particular for direct methanol fuel cells (DMFC). The inventive polymers may be manufactured in membrane form, and can be dissolved into solution and impregnated into porous substrates to form composite polymer electrolyte membranes with improved properties.