QENS investigation of proton confined motions in hydrated perfluorinated sulfonic membranes and self-assembled surfactants

Berrod, Quentin; Lyonnard, Sandrine; Guillermo, Armel; Ollivier, Jacques; Frick, B.; Gebel, Gérard

doi:10.1051/epjconf/20158302002

Cited by 19 publications

(45 citation statements)

References 36 publications

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“…Unfortunately, even the most modern scattering techniques provide averaged spatial information only 21 , which does not allow to form a comprehensive consistent picture of both the organization of these extremely complex materials at the nanoscale, and the consequent impact on transport properties. Hydrated sulfonated ionic surfactants have therefore been proposed as model systems for the local organization of ionomers, to quantify, among other issues, the effects of well-controlled confining geometries on proton mobility 17 .…”

Section: Discussionmentioning

confidence: 99%

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Water confined in self-assembled ionic surfactant nano-structures

2015

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We present a coarse-grained model for ionic surfactants in explicit aqueous solutions, and study by computer simulation both the impact of water content on the morphology of the system, and the consequent effect of the formed interfaces on the structural features of the adsorbed fluid. On increasing the hydration level at ambient conditions, the model exhibits a series of three distinct phases: lamellar, cylindrical and micellar. We characterize the different structures in terms of diffraction patterns and neutron scattering static structure factors. We demonstrate that the rate of variation of the nano-metric sizes of the self-assembled water domains shows peculiar changes in the different phases. We also analyse in depth the structure of the water/confining matrix interfaces, the implications of their tunable degree of curvature, and the properties of water molecules in the different restricted environments. Finally, we discuss our results compared to experimental data and their impact on a wide range of important scientific and technological domains, where the behavior of water at the interface with soft materials is crucial.

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Section: Discussionmentioning

confidence: 99%

“…Much more complex ionomer membranes, like Nafion, have also been extensively scrutinized 15 . Yet, relatively scarce studies have been devoted to the understanding of water structure and dynamics in ionic surfactants, in different hydration conditions 16,17 .…”

Section: Introductionmentioning

confidence: 99%

Water confined in self-assembled ionic surfactant nano-structures

2015

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“…In contrast, upon decreasing hydration, D ef f is strongly suppressed, with this ef- The values for D eff selected by the two verticals lines of the above panel are shown as closed symbols. We also show the diffusion coefficients obtained by PFG-NMR and QENS spectroscopy [23], which probe the dynamics on long and short length scales, respectively. fect becoming increasingly evident as the measured r 2 increases.…”

Section: A Evidence Of Sub-diffusive Behaviourmentioning

confidence: 99%

Sub-diffusion and population dynamics of water confined in soft environments

2016

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We have studied by Molecular Dynamics computer simulations the dynamics of water confined in ionic surfactants phases, ranging from well ordered lamellar structures to micelles at low and high water loading, respectively. We have analysed in depth the main dynamical features in terms of mean squared displacements and intermediate scattering functions, and found clear evidences of sub-diffusive behaviour. We have identified water molecules lying at the charged interface with the hydrophobic confining matrix as the main responsible for this unusual feature, and provided a comprehensive picture for dynamics based on a very precise analysis of life times at the interface. We conclude by providing, for the first time to our knowledge, a unique framework for rationalising the existence of important dynamical heterogeneities in fluids absorbed in soft confining environments.

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“…, E is the transferred energy, T is the temperature and kB is the Boltzmann constant 40 . Dynamic susceptibility excludes the contribution of elastic term and easily unveil different dynamic process 31,41,42 . Figure 2 shows dynamic susceptibility of CNF600 and CNF1500 at selected temperature and water content (full set of dynamic susceptibility is available in support information).…”

Section: Resultsmentioning

confidence: 99%

Water Dynamics in Hydrated Carboxylated Cellulose Nanofibril Membranes

Yu¹,

Guccini²,

Demmel³

et al. 2019

Preprint

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Cellulose nanofibrils (CNF) are a class of materials with good mechanical properties, surface functionality and bio-/environmental friendliness. They have been used in many applications as loading material or function materials, where water-cellulose interaction determines the materials performance.Especially, CNF with carboxylated groups can be used as the separation membrane in polymer electrolyte membrane fuel cell. The water dynamics is closely related to the proton conductivity. The Non-destructive quasi-elastic neutron scattering (QENS) is used to characterized water movement in hydrated membrane made of CNF prepared by TEMPO-oxidation with different surface charges.However, neither surface charge nor the nanoconfinement due to membrane swelling has large impact on water dynamics mechanism. A slow diffusive motion is found with the diffusion coefficient close to bulk water and that in hydrated Nafion membrane regardless the surface charge, while a fast motion is rather localized with a correlation time increasing as temperature increase, which might related to the hydrogen bond network formation between water and CNF. † Present address: RISE Introduction:The water -cellulose interaction is one of the most important scientific topics in the field of woodbased material science. It does not only conceal the secret behind the plant growth, but also determines processing parameters and performance of the final wood-based materials. In nature, cellulose polymer chains self-assemble into nanofibrils which consist of alternative crystalline and non-crystalline region along the fibril long axis. These so-called cellulose nanofibrils (CNF) serve as basic building block and are further organized with other biopolymer in water media to form the plant cell wall. 1 Compared to many wood-based materials, CNF to the largest extent keep the strong nature of cellulose materials, i.e. preserving excellent mechanical properties 2,3 . Meanwhile, the high surface-to-volume ratio enables a large surface area per unit weight and the extensive hydroxyl group exposed on the CNF surface could be easily modified and functionalized 4,5 . Especially, the carboxylation of CNF by the TEMPO-oxidation process has now become a common step for most of application as it delivers fine cross-section and activated carboxylated surface ligands 6 . Additionally, CNF are readily extractable from the pulp fibres and biodegradable. Thus, they have become a popular material platform for developing novel composites 4,5,7-9 . Among many applications, the good mechanical property of CNF has attracted most of the attention for engineering materials. Moisture content in CNF based materials influence both stiffness and strength 10 . On top of the robustness, the CNF could be used alone and/or as a carrier to load other functional materials for versatile purposes in optics 11 , electronics 12 and energy device 13 , where moisture content and electrolyte are closely relavent. Recently, CNF membranes with surface functional group have been successfully tested a...

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QENS investigation of proton confined motions in hydrated perfluorinated sulfonic membranes and self-assembled surfactants

Cited by 19 publications

References 36 publications

Water confined in self-assembled ionic surfactant nano-structures

Water confined in self-assembled ionic surfactant nano-structures

Sub-diffusion and population dynamics of water confined in soft environments

Water Dynamics in Hydrated Carboxylated Cellulose Nanofibril Membranes

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