Fluorene-containing sulfonated poly(arylene ether 1,3,4-oxadiazole) as proton-exchange membrane for PEM fuel cell application

Fluorene-containing polymers were synthesized followed by sulfonation into a series of fluorene-containing sulfonated poly(arylene ether oxadiazole)s (SPAEO) using chlorosulfonic acid. The sulfonic acid groups can be controlled to be only attached onto the fluorenyl rings by optimizing the reaction conditions. Their properties of ionic exchange capacity, sulfonation degree, water-uptake, mechanical property, thermal and oxidative stabilities as well as proton conductivity of the synthesized SPAEO membranes were fully investigated. It was found that the synthesized SPAEO with the sulfonic acid groups on fluorenyl rings exhibited superior oxidative stability and highly proton conductivity when compared with other reported sulfonated poly(arylene ether)s. Therefore, they showed potential alternatives as the proton-exchange membrane for fuel cell application.