A series of anion conductive aromatic ionomers, poly(arylene ether)s containing different polymer backbones and quaternized ammonio-substituted fluorenyl groups, were synthesized via nucleophilic substitution polycondensation, chloromethylation, quaternization, and the subsequent ion exchange reactions. The ion exchange capacity (IEC) of the ionomers was controlled to be from 0.68 to 2.54 meq. g⁻¹ by the chloromethylation reaction conditions. The designed chemical structures were well-characterized by the ¹H NMR spectra. The ionomers provided ductile and transparent membranes. The ionomer membranes were thermally stable up to 180 °C under nitrogen and mechanically stable with 48 MPa of the maximum stress at 80 °C and 60% RH (relative humidity). High hydroxide ion conductivity up to 50 mS cm⁻¹ was achieved at 30 °C in water for the ionomer membrane bearing sulfone/ketone structures and the highest IEC (2.54 meq. g⁻¹). The membranes were durable in hot water (80 °C) for 1000 hours. These properties of the ionomer membranes seem promising as an anion exchange membrane for alkaline fuel cells.

We now demonstrate a new class of a polymer proton exchange membrane for fuel cells, capable of combining low cost and high proton conductivity under low humidity conditions. The novel phosphoric acid (PA)-doped sulfonated polyimide (SPI) and polybenzimidazole (PBI) blend membrane enables proton conductivities of approximately 0.5 and 0.1 S cm⁻¹ at 120 °C and 45%RH and at 30 °C and 30%RH, respectively. These conductivities were approximately two orders of magnitude higher than those of Nafion 117 due to a new proton transport pathway between phosphoric acid and sulfonic acid in the blend membrane. In addition, the membrane showed no signs of performance degradation at 120 °C and 0%RH after 1000 hours of operation, and maintained a proton conductivity value of more than 0.01 S cm⁻¹. Consequently, this material shows promise as a novel proton exchange membrane and may have potential applications for use in fuel cells.