Preparation of acid-functionalized poly(phenylene oxide)s and poly(phenylene sulfone) and their proton conductivity

A series of highly acid-functionalized poly(phenylene oxide)s and poly(phenylene sulfone) were prepared and proton conductivity in their membranes is discussed. Phosphorylated poly(phenylene oxide)s were prepared via the oxidative polymerization of phosphonoxyphenols in alkaline water, along with a facile monomer preparation. A poly(phenylene oxide) bearing a sulfamide acid group was prepared by reacting amidosulfate with the corresponding carboxylated poly(phenylene oxide). A sulfonated poly(phenylene sulfone) was prepared by hydrogen peroxide oxidation of the sulfonated poly (phenyl ene sulfide). All these acid-functionalized polymers showed appropriate thermal stability based on the aromatic backbone. The polymers had a high ion-exchange capacity, were water-soluble, but gave transparent and flexible membranes after compositing with the poly(ethylene oxide). Some of the membranes displayed a high proton conductivity of 10^-4 S cm^-1 at 120 °C under dry conditions.