Aggregation of Ionomer and Carbon Blacks during MEA
                                                Preparation: Model to Characterize Particle Size and
                                                Catalyst Accessibility

Zook, Lois Anne

doi:10.1149/199827.0010pv

Cited by 2 publications

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“…See Table for values of E calculated from eq 3, where ε = 20 and r is taken as 0.5( r + + r - ). The radius of the sulfonate, r - , is taken as 0.35 nm based on the radii of similar ions, NO 3 - (0.3 nm), ClO 3 - (3.5 nm), and HSO 3 - (0.4−0.45 nm), and the diameter of the fluorocarbon side chain binding the sulfonate to the Nafion backbone (0.41 nm).…”

Section: Discussionmentioning

confidence: 99%

Density of Nafion Exchanged with Transition Metal Complexes and Tetramethyl Ammonium, Ferrous, and Hydrogen Ions: Commercial and Recast Films

2002

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The densities of commercial Nafion 117 and cast Nafion 1100 films were determined by the hydrostatic weighing method for films fully exchanged with hexaammineruthenium(III), tris(2,2' bipyridyl)ruthenium(II), tetramethylammonium, ferrous, and hydrogen ions. Films were pretreated in either water or concentrated nitric acid prior to cation exchange. All densities ranged between 1.65 and 2.19 g/cm3. Excluding the proton-exchanged films, the average density is 1.90 +/- 0.14 g/cm3, well in excess of the 1.58 g/cm3 commonly employed for Nafion. The density of acid-pretreated Nafion 1100 was constant at 1.95 +/- 0.03 g/cm3 for all cations except the proton. A simple, empirical model based on the Coulombic interaction between the intercalated cation and the sulfonate sites of the Nafion characterizes density for the commercial Nafion 117 films. A modified version of the model is appropriate for water-treated Nafion 1100. Water content of the films and implications for characterizing modified electrodes are discussed.

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Section: Discussionmentioning

confidence: 99%

Density of Nafion Exchanged with Transition Metal Complexes and Tetramethyl Ammonium, Ferrous, and Hydrogen Ions: Commercial and Recast Films

2002

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“…Several factors dominate the structures and chemistry at the interface between Nafion and the substrate polymers in the microbead and polycarbonate membrane composites. These include the chemical surface of the substrate polymer, the packing geometry of Nafion in the composite, and the balance of energetics between the cohesive energy of the fluorocarbon chains, the repulsive interactions between the hydrophilic and hydrophobic components of the Nafion and substrate polymers, and deformation of the substrate structure …”

Section: Discussionmentioning

confidence: 99%

Ion Exchange Capacity of Nafion and Nafion Composites

Chen

Leddy

2000

Langmuir

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The ion exchange capacity of recast Nafion films and composites of Nafion and polystyrene microbeads is determined by titration. Composite formation enhances exchange capacity; exchange capacity increases with the surface area of microbeads in the composite. For recast films, an equivalent weight of 996 ± 24 is found, whereas the lowest equivalent weight (highest exchange capacity) found for a composite is 878 ± 8. This suggests that ≳13% of the exchange sites within recast films are inaccessible for ion exchange; for 1100 equivalent weight material, ≳25% of the sulfonates are inaccessible. Equivalent weight results are consistent with an ordered interfacial domain between Nafion and the microbeads. A fractal model based on microbead radii, microbead fraction, and interfacial domain thickness provides a predictive model for designing composites with increased exchange capacity and cation transport.

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Aggregation of Ionomer and Carbon Blacks during MEA Preparation: Model to Characterize Particle Size and Catalyst Accessibility

Cited by 2 publications

References 0 publications

Density of Nafion Exchanged with Transition Metal Complexes and Tetramethyl Ammonium, Ferrous, and Hydrogen Ions: Commercial and Recast Films

Density of Nafion Exchanged with Transition Metal Complexes and Tetramethyl Ammonium, Ferrous, and Hydrogen Ions: Commercial and Recast Films

Ion Exchange Capacity of Nafion and Nafion Composites

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