Size and shape of Nafion particles in water after high‐temperature treatment

Yamaguchi, Makoto; Terao, Takeshi; Ohira, Akihiro; Hasegawa, Naoki; Shinohara, Kazuhiko

doi:10.1002/polb.24833

Cited by 8 publications

(12 citation statements)

References 27 publications

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“…Although aggregates of ionomers, carbon supports and carbon-supported platinum catalysts, as well as segregation of ionomers around the catalysts were clearly imaged with a high spatial resolution, those microstructures might be compromised by the freezing procedures. , Thus, in situ techniques to image the adsorbed ionomers on platinum and carbon surfaces in a molecular/nanometer scale are strongly desired to achieve the better control of kinetic activity and mass transport property of MEAs. Several groups applied in situ experimental techniques − and theoretical methods − to the structural investigation of ionomers and proposed various morphologies under the influence of different solvents and thermal treatments.…”

Section: Introductionmentioning

confidence: 99%

Solvent-Dependent Adsorption of Perfluorosulfonated Ionomers on a Pt(111) Surface Using Atomic Force Microscopy

Devivaraprasad

Masuda

2020

Langmuir

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The adsorption behavior of perfluorosulfonated ionomers (PFSIs) on a Pt(111) surface in various solvents is investigated by in situ atomic force microscopy (AFM) and discussed on the basis of aggregation of PFSIs in the liquid phase. The AFM images show that, in an aqueous solution of PFSI (0.1 wt % Nafion + 99.9 wt % water), PFSI aggregates with a lateral size of 20−200 nm adsorb on the Pt(111) surface. In a PFSI solution containing a small amount of 1-propanol (0.1 wt % Nafion + 99.5 wt % water + 0.4 wt % 1-propanol), however, slightly smaller aggregates adsorb on the Pt(111) surface. Such solvent-dependent sizes of adsorbed aggregates are in reasonable agreement with apparent hydrodynamic radii of PFSIs in the corresponding solutions determined by dynamic light scattering (DLS) while assuming the formation of spherical aggregation. Interestingly, a step-terrace structure characteristic to a clean Pt(111) surface is observed in a propanol-rich PFSI solution (0.1 wt % Nafion + 44.45 wt % water + 55.45 wt % 1-propanol) but X-ray photoelectron spectroscopy clearly indicates the existence of fluorocarbon species at the Pt(111) surface, suggesting the formation of a smooth adsorbed layer of PFSIs in a lying down configuration. Absence of any features assignable to aggregates in DLS data suggests well-dispersion of PFSIs in such propanol-rich solution without aggregations. Thus, the adsorbed structure of PFSIs at Pt surfaces can be controlled by tuning the composition of mixed solvent, which affects the aggregation of PFSI in the liquid phase.

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Section: Introductionmentioning

confidence: 99%

Solvent-Dependent Adsorption of Perfluorosulfonated Ionomers on a Pt(111) Surface Using Atomic Force Microscopy

Devivaraprasad

Masuda

2020

Langmuir

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“…Cryo-EM is the obvious choice for characterization since it operates while hydrated. Yamaguchi et al performed cryo-TEM on dispersed Nafion particles before and after heating [29]. Allen et al performed cryogenic electron tomography (cryo-ET) of an as-cast 100 nm frozen-hydrated Nafion membrane and identified a random channel-type interconnected network of hydrophilic domains [30].…”

Section: Tem Lamellae Of Energy and Soft Materials Using Cryo-fibmentioning

confidence: 99%

Cryo-FIB for TEM investigation of soft matter and beam sensitive energy materials

Long¹,

Singh²,

Small³

et al. 2022

Nanotechnology

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Primarily driven by structural biology, the rapid advances in cryogenic electron microscopy (cryo-EM) techniques are now being adopted and applied by materials scientists. Samples that inherently have electron transparency can be rapidly frozen (vitrified) in amorphous ice and imaged directly on a cryogenic transmission electron microscopy (cryo-TEM), however this is not the case for many important materials systems, which can consist of layered structures, embedded architectures, or be contained within a device. Cryogenic focused ion beam (cryo-FIB) lift-out procedures have recently been developed to extract intact regions and interfaces of interest, that can then be thinned to electron transparency and transferred to the cryo-TEM for characterization. Several detailed studies have been reported demonstrating the cryo-FIB lift-out procedure, however due to its relative infancy in materials science improvements are still required to ensure the technique becomes more accessible and routinely successful. Here, we review recent results on the preparation of cryo-TEM lamellae using cryo-FIB and show that the technique is broadly applicable to a range of soft matter and beam sensitive energy materials. We then present a tutorial that can guide the materials scientist through the cryo-FIB lift-out process, highlighting recent methodological advances that address the most common failure points of the technique, such as needle attachment, lift-out and transfer, and final thinning.

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“…3,6 The simulation revealed the formation of rod-like bundles of ionomers in the diluted solution. As suggested in several experimental studies, 10,22 hydrophilic sulfonate groups are distributed on the surfaces of these bundles, which form micellar structures that enable the stable dispersion of the bundles in the solution. Unlike the discontinuous transition proposed by Gebel, 13 our simulation demonstrated a continuous structural transition from the solution to the solid electrolyte.…”

mentioning

confidence: 93%

Mechanism of Ionomer Film Formation via Solution Drying

Kinjo,

Hasegawa,

Yamakawa

et al. 2024

ACS Macro Lett.

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Film formation via the drying of ionomer solutions is a crucial process that has a strong influence on the morphology and transport properties of polymer electrolyte membranes and thin films. However, the microscopic mechanism of this process remains unclear. Here, we elucidate this mechanism using a coarsegrained model based on all-atom molecular dynamics that accurately reproduces small-angle X-ray scattering spectra. In dilute ionomer solutions, ionomers form rod-like bundles with diameters of 1.5−2 nm. As the water solvent evaporates, these bundles gradually aggregate and connect to each other, while maintaining their diameter. Finally, the remaining water forms nanosized clusters surrounded by the surfaces of the bundles with hydrophilic sulfonate groups.

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Size and shape of Nafion particles in water after high‐temperature treatment

Cited by 8 publications

References 27 publications

Solvent-Dependent Adsorption of Perfluorosulfonated Ionomers on a Pt(111) Surface Using Atomic Force Microscopy

Solvent-Dependent Adsorption of Perfluorosulfonated Ionomers on a Pt(111) Surface Using Atomic Force Microscopy

Cryo-FIB for TEM investigation of soft matter and beam sensitive energy materials

Mechanism of Ionomer Film Formation via Solution Drying

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