A new high-molecular-weight, soluble, wholly aromatic polyether bearing polar pyridine and phosphinoxide groups along the main chain is presented. This easily processable polyether presents excellent film-forming properties, high glass-transition temperature (up to 260 °C), and thermal stability up to 500 °C, all together combined with an ability to form ionically conductive materials after doping with phosphoric acid. The polar groups throughout the polymeric chains enable high acid uptake and subsequent high ionic conductivity for the doped membranes in the range of 10 -2 S/cm. Characterization of all polymeric materials prepared was performed using NMR, size exclusion chromatography, thermal and mechanical analysis, and conductivity measurements. The oxidative stability of the materials was studied using hydrogen peroxide, and the treated membranes were further characterized using dynamic mechanical analysis and FT-Raman spectroscopy. The conductivity of the doped membranes was determined as a function of the doping level. The temperature dependence of the conductivity was also studied.

Summary: Novel poly(aryl ether sulfone) copolymers containing 2,5‐biphenylpyridine and tetramethyl biphenyl moieties were synthesized by polycondensation of 4‐fluorophenyl sulfone with 2,5‐(4′,4″ dihydroxy biphenyl)pyridine and tetramethyl biphenyl diol. Copolymers with different molecular weights and different monomer compositions were obtained. These copolymers exhibit excellent film‐forming properties, mechanical integrity, and high modulus up to 250 °C, high glass transition temperatures (above 280 °C) as well as high thermal stability up to 400 °C. In addition to the above properties required for PEMFC application, this novel material shows high oxidative stability and acid doping ability, enabling proton conductivity in the range of 10−2 S · cm−1 above 130 °C.Synthesis of copolymers with high acid uptake and ionic conductivity.magnified imageSynthesis of copolymers with high acid uptake and ionic conductivity.

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