Sorption and diffusion behaviors of water in Nation 117 membranes with different counter ions

Legras, Marc; Hirata, Yuichi; Nguyen, Quang Trong; Langévin, D.; Métayer, M. Le

doi:10.1016/s0011-9164(02)00608-2

Cited by 86 publications

(82 citation statements)

References 12 publications

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“…They were then soaked in distilled-deionized water at 50 C for 4 hours and rinced with fresh distilled water. The obtained data substantially agree with those reported in ref [7,8] for Nafion 117.…”

Section: Nafion and Sulfonated Polyimidessupporting

confidence: 92%

Water Dynamics in Ionomer Membranes by Field‐Cycling NMR Relaxometry

et al. 2006

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The water dynamics of two types of ionomer membranes, the Nafion® and sulfonated polyimides, have been investigated by field‐cycling nuclear magnetic relaxation. This technique, applied to samples prepared at different water content, allows to characterize the proton motion at the time scale of the microsecond. The polyimides appear to behave as standard porous materials, whereas in the Nafion®, we have observed two different dynamical regimes related to a complex swelling process.

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Section: Nafion and Sulfonated Polyimidessupporting

confidence: 92%

Water Dynamics in Ionomer Membranes by Field‐Cycling NMR Relaxometry

et al. 2006

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“…In the whole investigated range of the hydration level (0 ≤ X ≤ 10), the binding energy per water molecules is stronger for Nafion containing the alkali ions as the counter-ions, because the alkali ions possess quite large surface charge density, which strengthens the electrostatic attraction of the water molecules. The static ab initio calculations are consistent with experimental observations demonstrating that the water diffusion coefficient is higher in H + form Nafion than in Na + or Li + forms [58][59][60]. Fig.…”

Section: …Hsupporting

confidence: 86%

Ab initio study of cationic polymeric membranes in water and methanol

Karpenko-Jereb

Rynkowska

Kujawski

et al. 2015

Ionics

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The work is devoted to a computational study of three types of cationic polymeric membranes in Li + -ionic form, in water and methanol environments, at various solvation levels. The studied membranes Nafion, IonClad, and M3 possess the perfluorinated backbone; however, various side chains were terminated with the functional groups of distinctly different ionic strength. The paper discusses the structural features of the membrane-solvent clusters as well as an influence of the side chain nature on the dissociation of the functional groups and the binding energy of the solvent molecules. Additionally, the paper compares the obtained results for Li + -Nafion membrane in water with the results published earlier for H + and Na + forms.

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“…The second step corresponds to the dissolution of water in the polymer phase and can be modelled by the Henry's linear equation. 31,32 The final upturn of the isotherm at higher water activities is linked to the macroscopic swelling of the membrane and thus is controlled by the membrane's mechanical properties. 9 The experimental isotherms of Figure 3 show that the maximum water uptake is much lower in the aged membrane than in the pristine sample.…”

Section: Resultsmentioning

confidence: 99%

Towards a NMR-Based Method for Characterizing the Degradation of Nafion XL Membranes for PEMFC

Robert¹,

Kaddouri²,

Perrin³

et al. 2018

J. Electrochem. Soc.

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PFSA-based reinforced membranes are used today as the benchmark material for the electrolyte in PEMFCs. Although greatly improved relatively to their unreinforced version, they still suffer from aging and degradation during fuel cell (FC) operation. In this study we first performed proton NMR to characterize the different water populations in the pristine Nafion XL reinforced membrane. Then we used proton and fluorine NMR, FTIR and sorption measurements in order to qualitatively observe the differences induced in the membrane's chemical structure and properties by long term FC operation. Proton NMR is seen to be an adapted tool to quickly measure a signature that is correlated to the degradation state while FTIR can serve as a local probe of the chemical structure. The degradation of the proton exchange membrane (PEM) is one of the main factors limiting the proton exchange membrane fuel cell (PEMFC) stability and performance.1,2 The development of PEM with increased durability remains thus today a critical obstacle that restricts the large scale spreading of PEMFC systems.The decomposition of the membrane is induced by several factors among which mechanical stress and chemical degradation prevail.The mechanical degradation is initiated by humidity cycling that creates alternating shrinkage/swelling events and a non-uniform stress distribution in the membrane plane. The resulting reduction of the polymer mechanical strength can lead to the formation of cracks and to the final failure of the membrane electrode assembly (MEA). 3-5The chemical decomposition of the PEM in the MEA is caused by gas crossovers. The electrochemical reactions of these gases cause the formation of free radicals and the attack of the polymer chemical structure, which results in scissions in the main chain and in the side chain and finally to the thinning of the membrane. 6,7 Many studies have focused on PEM chemical degradation and a comprehensive review of the current understanding of the mechanisms in perfluorosulfonic acid (PFSA) membranes was recently published. 8 PFSA membranes, such as Nafion, Flemion or Aciplex are today the most widely used fuel cell electrolytes thanks to their good chemical robustness and their high proton conductivity.9 Through the years, efforts have been made to reduce the membrane's ionic resistivity without compromising the mechanical properties. This was made possible by the introduction of chemical stabilizers and mechanical reinforcement. For instance, the Nafion XL is a reinforced membrane composed of two external PFSA layers with stabilizers to reduce chemical attack and a central microporous polytetrafluoroethylene (PTFE)-rich support layer to provide additional mechanical strength and enable the use of thinner ionomer. The central PTFE layer is impregnated with ionomer to provide a continuous conductive pathway across the membrane's thickness.The structure and basic properties of the Nafion XL membrane were investigated by Shi and co-workers. 10 The authors examined the effect of reinforcement and pre-...

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Sorption and diffusion behaviors of water in Nation 117 membranes with different counter ions

Cited by 86 publications

References 12 publications

Water Dynamics in Ionomer Membranes by Field‐Cycling NMR Relaxometry

Water Dynamics in Ionomer Membranes by Field‐Cycling NMR Relaxometry

Ab initio study of cationic polymeric membranes in water and methanol

Towards a NMR-Based Method for Characterizing the Degradation of Nafion XL Membranes for PEMFC

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