An extensive SAXS investigation of the 3M perfluorinated sulfonic acid ionomer was performed to investigate the morphological changes that occur during and after annealing at temperatures above the T α. The effect of film thickness in the range studied, 11–45 μm, was found to be negligible. These properties were studied as a function of equivalent weight from 700 to 1100 and correlated with the water uptake as measured by dynamic vapor sorption. Isoscattering points were observed in dynamic annealing experiments of the unboiled annealed films at q = 0.023, 0.096 Å–1. On initial water uptake these films also showed isoscattering points at q = 0.024, 0.220 Å–1; q = 0.029, 0.223 Å–1; and q = 0.030, 0.211 Å–1 at 50, 80, or 95 °C, respectively, indicating a decrease in the symmetry of the scattering objects in these size regimes. Isoscattering points were absent in similar water uptake experiment for the films after boiling.

Copolymers of vinylphosphonic acid with zirconium vinylphosphonate have been synthesized via free radical polymerization from immiscible mixtures into amorphous, transparent, water stable, and flexible membranes. Ion exchange capacities range from 6 to 10 mequiv/g, corresponding to equivalent weights well below 200 g/mol. A 20 wt % loading of the vinyl zirconium phosphonate comonomer is XRD amorphous. It is shown that 1.5 of the 2 protons in the beginning acidic groups are dissociated in the 20 wt % VZP loaded ionomer, allowing these materials to have high proton conductivities, up to and exceeding 0.1 S cm–1 at 80 °C and 80% RH. Water uptake measurements show very little swelling of the material below 70% RH and ca. 1 water per proton at low RH. Proton conductivity under dry conditions, roughly 0.05 S cm–1 with a λ < 1, indicates that the material conducts protons under limiting hydration conditions and strongly implicates transport by a pure Grotthuss mechanism.

Phosphonic acid based fuel cell membranes show promise for making polymer electrolyte membranes that can operate at higher temperatures, >100C and low relative humidity. A copolymer of vinyl phosphonic acid with vinyl zirconium phosphonate has been synthesized into a clear, flexible, amorphous membrane. Chemical characterization has been accomplished using EDX, FTIR and CPMAS NMR. XRD and SAXS have been used to confirm an amorphous nature. EIS and PFGSE NMR have been used to characterize the ionic transport through the membrane on different length scales.

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Copolymers of vinyl phosphonic acid with zirconium vinyl phosphonate have been synthesized via free radical polymerization from immiscible mixtures into amorphous, transparent, water stable, flexible membranes. Ion exchange capacities range from 6 to 10 meq/g corresponding to equivalent weights well below 200 g/mol. A 20wt% loading of the vinyl zirconium phosphonate co-monomer is XRD amorphous. It is shown that 1.5 of the 2 protons in the beginning acidic groups are dissociated in the 20wt% VZP loaded ionomer allowing these materials to have high proton conductivities, up to and exceeding 0.1 S cm-1 at 80{degree sign}C and 80%RH. Water uptake measurements show very little swelling of the material below 70%RH and ca. 1 water per proton at low RH. Proton conductivity under dry conditions, roughly 0.05 S cm-1 with a lambda < 1, indicates that the material conducts protons under limiting hydration conditions and strongly implicates transport by a pure Grotthuss mechanism.