Polyaromatic ionomers with a highly hydrophobic backbone and perfluorosulfonic acids for PEMFC

Highlights: • Substitution of the polymer backbone with perfluorosulfonic acid in one step. • Design of ionomers with very hydrophobic backbone. • The ionomers show better proton conducting properties than the Nafion. • The ionomers show moderate water uptake even at high ion exchange capacity. - Abstract: The publication reports, for the first time, on the synthesis of aromatic-based ionomers bearing superacid side groups bonded to a highly hydrophobic fluorinated aromatic backbone. The incorporation of the side group on the backbone takes place in one step via a nucleophilic substitution. The membranes obtained from these new ionomers show phase separation at nanoscale and moderate water uptake even at high ion exchange capacity (IEC), i.e. 1.7 meq/g. Additionally, their conductivity and mechanical strength are much higher than those of the benchmarked ionomer Nafion^®, which makes them very promising materials for fuel cell application.