Fluorinated Poly(Aryl Ether) Superacidic Ionomers

Superacidic ionomers are synthesized via CH activation/borylation followed by Suzuki coupling of aromatic rings of fluorinated poly(arylene ether)s. Properties of these superacidic ionomers, such as thermal stability, water uptake, ion exchange capacity (IEC), morphology, and proton conductivity, are systematically investigated. For comparative analysis, a polysulfone ionomer with a similar IEC was examined to elucidate the effect of polymer backbone hydrophobicity on membrane properties. The results demonstrate that polymer backbone hydrophobicity exerts a significant impact on both morphology and performance. Highly fluorinated poly(aryl ether) ionomers exhibit reduced water uptake and enhanced proton conductivity compared to low‐fluorine or nonfluorinated polymer analogs. Notably, the TFHFBP‐S 1 membrane achieves the highest proton conductivity, comparable to that of Nafion, across the full range of relative humidity at 100 °C.