Effect of Perfluoroalkyl Chain Length on Proton Conduction in Fluoroalkylated Phosphonic, Phosphinic, and Sulfonic Acids

Herath, Mahesha B.; Creager, Stephen E.; Kitaygorodskiy, Alex; DesMarteau, Darryl D.

doi:10.1021/jp107190q

Cited by 16 publications

(17 citation statements)

References 11 publications

(30 reference statements)

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“…The fluorinated phosphonic acid C 6 F 5 P(O)(OH) 2 (7.38 × 10 −5 S cm −1 at 120 °C) and polymer 6 exhibit a significantly higher conductivity than C 6 H 5 P(O)(OH) 2 (1.98 × 10 −7 S cm −1 at 120 °C). This is in accordance with the assumption that fluorination has a major impact on the conductivity of phosphonic acid materials . Under the given conditions, the conductivity of Nafion (7.66 × 10 −5 S cm −1 at 120 °C) is similar to that of C 6 F 5 P(O)(OH) 2 .…”

Section: Resultssupporting

confidence: 89%

“…Phosphonic acid based materials are promising candidates to overcome these drawbacks. Conductivity studies by DesMarteau and coworkers identified perfluoroalkyl phosphonic acids as highly proton conducting species, which are even superior to perfluoroalkyl sulfonic acids under anhydrous conditions. The Grotthuss mechanism emphasizes that the proton conductivity of phosphonic acids is due to their amphoteric nature.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of a novel difluoromethylene phosphonic acid functionalized polymer

Alter

Hoge

2018

J of Applied Polymer Sci

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A novel polymer featuring difluoromethylene phosphonic acid functions was prepared by free radical polymerization of a styrene monomer that is decorated by phosphonic ester groups. The obtained polymer was analyzed by gel permeation chromatography, differential scanning calorimetry, and spectroscopy (NMR, infrared). Treatment of the polymeric phosphonic ester with Me 3 SiBr led to an exchange of the ethyl groups by trimethylsilyl units in the P-containing part of the material. Desilylation to the free phosphonic acid functions was effected by water. The ion exchange capacity was determined to be 7.3 mmol/g by titration with 0.1 M NaOH. The proton conductivity in the anhydrous state was studied by electrochemical impedance spectroscopy. The conductivity of 1.76 × 10 −5 S cm −1 at 120 C is well comparable with that of Nafion (7.66 × 10 −5 S cm −1 at 120 C), and renders this polymeric phosphonic acid as a promising candidate for proton conduction applications.

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of a novel difluoromethylene phosphonic acid functionalized polymer

Alter

Hoge

2018

J of Applied Polymer Sci

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“…Haven ratios much higher than unit have also been reported for proton transport in imidazole based anhydrous membranes 45 and anhydrous ionomers. 46,47 CONCLUSIONS WAXS diffractograms of the hydrated membranes described in this work exhibit at low angles an ionomer peak located at q = 2.66 nm…”

Section: Discussionmentioning

confidence: 75%

Influence of the Water Content on the Diffusion Coefficients of Li⁺ and Water across Naphthalenic Based Copolyimide Cation-Exchange Membranes

et al. 2012

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The transport of lithium ions in cation-exchange membranes based on sulfonated copolyimide membranes is reported. Diffusion coefficients of lithium are estimated as a function of the water content in membranes by using pulsed field gradient (PFG) NMR and electrical conductivity techniques. It is found that the lithium transport slightly decreases with the diminution of water for membranes with water content lying in the range 14 < λ < 26.5, where λ is the number of molecules of water per fixed sulfonate group. For λ < 14, the value of the diffusion coefficient of lithium experiences a sharp decay with the reduction of water in the membranes. The dependence of the diffusion of lithium on the humidity of the membranes calculated from conductivity data using Nernst−Planck type equations follows a trend similar to that observed by NMR. The possible explanation of the fact that the Haven ratio is higher than the unit is discussed. The diffusion of water estimated by 1 H PFG-NMR in membranes neutralized with lithium decreases as λ decreases, but the drop is sharper in the region where the decrease of the diffusion of protons of water also undergoes considerable reduction. The diffusion of lithium ions computed by full molecular dynamics is similar to that estimated by NMR. However, for membranes with medium and low concentration of water, steady state conditions are not reached in the computations and the diffusion coefficients obtained by MD simulation techniques are overestimated. The curves depicting the variation of the diffusion coefficient of water estimated by NMR and full dynamics follow parallel trends, though the values of the diffusion coefficient in the latter case are somewhat higher. The WAXS diffractograms of fully hydrated membranes exhibit the ionomer peak at q = 2.8 nm−1, the peak being shifted to higher q as the water content of the membranes decreases. The diffractograms present additional peaks at higher q, common to wet and dry membranes, but the peaks are better resolved in the wet membranes. The ionomer peak is not detected in the diffractograms of dry membranes.

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“…Practical synthesis of these acids was developed in a collaboration between Merck KGaA and the Willner research group [140][141][142]. They exhibit high oxygen solubility and proton conductivity under anhydrous conditions.…”

Section: Alternative Acidsmentioning

confidence: 99%

Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells

2017

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High temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are being studied due to a number of benefits offered versus their low temperature counterparts, including co-generation of heat and power, high tolerance to fuel impurities, and simpler system design. Approximately 90% of the literature on HT-PEM is related to the electrolyte and, for the most part, these electrolytes all use free phosphoric acid, or similar free acid, as the ion conductor. A major issue with using phosphoric acid based electrolytes is the free acid in the electrodes. The presence of the acid on the catalyst sites leads to poor oxygen activity, low solubility/diffusion, and can block electrochemical sites through phosphate adsorption. This review will focus on these issues and the steps that have been taken to alleviate these obstacles. The intention is this review may then serve as a tool for finding a solution path in the community.

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Effect of Perfluoroalkyl Chain Length on Proton Conduction in Fluoroalkylated Phosphonic, Phosphinic, and Sulfonic Acids

Cited by 16 publications

References 11 publications

Synthesis and characterization of a novel difluoromethylene phosphonic acid functionalized polymer

Synthesis and characterization of a novel difluoromethylene phosphonic acid functionalized polymer

Influence of the Water Content on the Diffusion Coefficients of Li⁺ and Water across Naphthalenic Based Copolyimide Cation-Exchange Membranes

Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells

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Effect of Perfluoroalkyl Chain Length on Proton Conduction in Fluoroalkylated Phosphonic, Phosphinic, and Sulfonic Acids

Cited by 16 publications

References 11 publications

Synthesis and characterization of a novel difluoromethylene phosphonic acid functionalized polymer

Synthesis and characterization of a novel difluoromethylene phosphonic acid functionalized polymer

Influence of the Water Content on the Diffusion Coefficients of Li+ and Water across Naphthalenic Based Copolyimide Cation-Exchange Membranes

Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells

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Influence of the Water Content on the Diffusion Coefficients of Li⁺ and Water across Naphthalenic Based Copolyimide Cation-Exchange Membranes