Synthesis and Properties of Sulfonated Poly(phthalazinone ether phosphine oxide)s with Perfluorobiphenyl Moieties for Proton Exchange Membranes

The poly (phthalazinone ether phosphine oxide)s with perfluorobiphenyl moieties were synthesized by copolycondensation of decafluorobiphenyl, bis (4-fluorophenyl) phenylphosphorus oxide, and 4-(4-hydrolphenyl) phthalazinone, which were then converted to the sulfonated poly (phthalazinone ether phosphine oxide)s with perfluorobiphenyl moieties (sPEPOF-x, x means the molar percentage of F-containing units) by sulfonation. The highly hydrophobic perfluorobiphenyl moieties facilitate to form the microphase seperation structures within polymer membranes, increasing the proton conductivity and decreasing the swelling ratio, thus the resultant membranes display superior comprehensive properties. At 80 degrees C, the sPEPOF-25 membrane presents a swelling ratio of only 10%, about half that of Nafion 117 membrane, whereas its proton conductivity is 0.099 S/cm, which is 1.2 times that of Nafion 117 membrane. It also possesses excellent thermal stability and oxidation resistance, showing potential application prospect.