Fig. 2: Molecular structures of ionomers.
From: The role of oxygen-permeable ionomer for polymer electrolyte fuel cells
a–c Molecular structures of Nafion ionomer (a), HOPI with PFMMD matrix reported in ref. 41 (b), and HOPI synthesized in this work (c). Density (ρ), number-average molecular weight (Mn), EW (ionomer mass per sulfonate group), and proton conductivity (σH) are also shown. The density was measured under dry conditions, and the proton conductivity shown here was obtained at 97% RH and room temperature.
