A novel array of copolytriazoles PYFTSH-XX, with semifluorinted structure in both hydrophilic and hydrophobic unit, were synthesized exploiting a novel trifluromethyl (-CF3) functionalized diazide monomer with flexible aromatic ether moiety in order to get enhancement simultaneously in both peroxide resistance and proton exchange property. These polytriazoles were synthesized by azide-alkyne cycloaddition polymerization of a novel per-fluro dialkyne monomer mixing with a newly synthesized trilfuromethylated ortho-blocked pyridine containing diazide; with or without a sulfonated diazide monomer. NMR (1H, 13C, and 19F) with FTIR studies approved the synthesis of polytriazoles with a quantitatively controlled variation in percentage of sulfonation. The membranes proved to possess high chemical, thermal durability and high tensile properties. Addition of -CF3 and sterically hindered pyridine units in polymer structure, with both ortho positions blocked, proved to play an important part in raising peroxide resistance by selective quenching of radicals, which was established by FTIR and pulsed EPR spectroscopy. The existence of pyridine unit in polymer structure also boosted proton conductivity owed to weak basicity of pyridine. HR-TEM and AFM micrographs of the specimens proved the creation of phase separation in morphology and that appeared extra prominent with the upsurge in the percentage of sulfonation. The membrane prepared from PYFTSH-90 displayed 139 mS cm−1 as proton conductivity at 80 °C (fully hydrated condition), which is comparable to Nafion®-117 under similar testing condition.

Synthesis of sterically hindered pyridine containing semi-fluorinated polyelectrolyte membranes with high peroxide resistance

ACS Spring Meeting 2021

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