Sulfonated poly(ether ether) ketone/polyurethane composites doped with phosphoric acids for proton exchange membranes

• Sulfonated poly(ether ether) ketone/polyurethane blend membranes were prepared via electrostatic interactions.
• Phosphoric acid doped membrane showed the thermal composition temperature up to 180 °C.
• A maximum proton conductivity of 3.0 × 10− 2 S cm− 1 was obtained at 160 °C under anhydrous conditions.

The performance of proton exchange membrane (PEM) is critically dependent on the selection of materials and the optimization of individual components. Polyurethane (PU) as a common polymer has the superior mechanical properties. However, the poor oxidation and thermal stability after doping phosphoric acids (PAs) prevented its application as PEM electrolytes. Here, we introduced the negatively charged sulfonated poly(ether ether) ketone (SPEEK) into the positively charged PU matrix, expecting to improve its performance after doping PA molecules. The strong electrostatic interaction enables the formation of homogenous and compact SPEEK/PU membranes. The decomposition temperature of SPEEK/PU/PA membrane could reach 180 °C, which was higher than 110 °C for PA doped PU membrane. Importantly, these prepared PA doped membranes presented the satisfactory proton conductivity and acceptable mechanical property. SPEEK/PU/PA(1/1/100) membrane possessed a maximum proton conductivity of 3.0 × 10− 2 S cm− 1 at 160 °C under anhydrous conditions.

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