Interaction of nafion ionomers toward various solvents

Kumar, Krishna; Vijayalakshmi, K. P.; Sivanath, Sangeetha; Jayalatha, T.; Mohanty, Surajeet; Shaneeth, M.

doi:10.1002/app.38421

Cited by 6 publications

(4 citation statements)

References 40 publications

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“…Indeed, the contact angle values between methanol and polytetrafluoroethylene (PTFE), and between water and PTFE were about 40 and 110°, respectively, whereas the volume expansions of Nafion were about 209 and 43%, respectively . These results can be explained by the solvation of the ionic sites but also by the plasticization of the polymer aggregates by the organic solvent (hydrophobic methyl group) . Pure methanol does not swell the PTFE polymer.…”

Section: Introductionmentioning

confidence: 95%

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Direct Extraction of Platinum Nanoparticles from Fuel Cells with Ionic Liquids: Part 2. Impact of the Nafion Ionomer Swelling

Coudray

Billy

Pouget

et al. 2023

Ind. Eng. Chem. Res.

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We reported a safer and greener process than those usually based on pyro-hydrometallurgical technologies to recover the Pt catalyst from membrane electrode assemblies (MEAs) without the need for the calcination step and dissolution of platinum nanoparticles (Pt NPs). Using a large panel of ionic liquids (ILs) with different physicochemical properties and varied cation/anion compositions, ILs were used as both extractants to recover directly the Pt NPs from the catalyst layer (CL) of MEAs as well as the stabilization agent of the detached Pt NPs. Our optimized process results in the extraction of metallic Pt up to >90% of the Pt initially present on the CL and also allows in a single step to detach the Pt NPs from its carbon support. Moreover, contact angle measurements revealed that ILs could interact with all the components of the active layer. Among the different interactions allowing the best results in terms of extraction, the Nafion-IL interaction seems to be of particular importance. Indeed, the variation of the ionomer content in the CL was directly correlated with the efficiency of extraction. Therefore, the interaction and wettability of ILs with the different components of the CL and particularly with the ionomer (swelling) are of prime importance and necessitate further studies to deepen our understanding of the mechanism of platinum extraction by ILs. This is the aim of the present detailed study, based on small-angle X-ray scattering and wide-angle X-ray scattering techniques, with a particular focus on the best IL candidate P 66614 Cl with membrane Nafion as a model system and with the ionomer contained in CL.

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Section: Introductionmentioning

confidence: 95%

“…25 These results can be explained by the solvation of the ionic sites but also by the plasticization of the polymer aggregates by the organic solvent (hydrophobic methyl group). 26 Pure methanol does not swell the PTFE polymer. Plasticization may become possible once the solvation of the ionic sites has taken place in Nafion.…”

Section: ■ Introductionmentioning

confidence: 99%

Direct Extraction of Platinum Nanoparticles from Fuel Cells with Ionic Liquids: Part 2. Impact of the Nafion Ionomer Swelling

Coudray

Billy

Pouget

et al. 2023

Ind. Eng. Chem. Res.

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“…A fourth protocol was tested to enhance the nanophase separation of the 2020 sPEEK membranes without excessive swelling. It consisted in inducing the swelling 30,31 through a hydro alcoholic step in water/ ethanol solution (64/36 vol%) before the hydrothermal treatment (80 C/72 h). This protocol was also applied for comparison to the 2019 batch.…”

Section: Third Pretreatment: Acidificationhydrothermal 72 H-acidifica...mentioning

confidence: 99%

“…18 In water, relatively long treatments were necessary to obtain well-defined ionic channels at temperatures close to T β (much shorter durations when T >> T β ). In order to reduce the temperature and the duration of the treatments, polar solvents such as alcohol, known to induce strong swelling 30,31 (mass and volume) of ionomer membranes (solvation of ionic sites and solvent plasticizing effect) were used to increase the macromolecular mobility.…”

Section: Introductionmentioning

confidence: 99%

Impact of sulfonated poly(ether ether ketone) membranes pretreatments on their physicochemical properties and fuel cell performances

Daoudi

Ferri

Tougne

et al. 2023

Journal of Polymer Science

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This work focuses on the impact of sulfonated poly(ether ether ketone) (sPEEK) membrane pretreatments on fuel cell performance, starting from two different batches of Fumapem E730 from Fumatech, acquired in 2019 and in 2020. sPEEK membranes are possible lower cost alternatives to perfluorosulfonic acid (PFSA) membranes for proton exchange membrane fuel cells (PEMFC) applications. Before use, they must be pretreated to ensure a complete protonic substitution and removal of residual reagents/solvent: the simplest protocol consists in soaking the membrane in an acid solution followed by a rinsing step in water. In addition to this acidification step, hydrothermal (HT) treatments in water at high temperature for a few hours to a few days were also considered herein, as well as a hydro‐alcoholic (HA) step, because of their expected effects on membrane nanostructure. Overall, four different protocols were used. The membrane water uptake, water self‐diffusion, proton conductivity, and fuel cell performance—under H2/O2—were measured. It was found that in the best case—membranes from the 2020 batch subjected to HA followed by 72 h HT pretreatments—the fuel cell performances exceeded those obtained with a PFSA membrane (Nafion XL). This is explained by a higher protonic conductivity, probably resulting from a better sPEEK nano‐structuration.

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