laboratoire de physique statistique
 
 
laboratoire de physique statistique

Publications

Rechercher
 
2016
Anomalous capillary filling and wettability reversal in nanochannels - Gravelle, Simon and Ybert, Christophe and Bocquet, Lyderic and Joly, Laurent
PHYSICAL REVIEW E 93 (2016) 
LPS


Abstract : This work revisits capillary filling dynamics in the regime of nanometric to subnanometric channels. Using molecular dynamics simulations of water in carbon nanotubes, we show that for tube radii below one nanometer, both the filling velocity and the Jurin rise vary nonmonotonically with the tube radius. Strikingly, with fixed chemical surface properties, this leads to confinement-induced reversal of the tube wettability from hydrophilic to hydrophobic for specific values of the radius. By comparing with a model liquid metal, we show that these effects are not specific to water. Using complementary data from slit channels, we then show that they can be described using the disjoining pressure associated with the liquid structuring in confinement. This breakdown of the standard continuum framework is of main importance in the context of capillary effects in nanoporous media, with potential interests ranging from membrane selectivity to mechanical energy storage.
Scaling Behavior for Ionic Transport and its Fluctuations in Individual Carbon Nanotubes - Secchi, Eleonora and Nigues, Antoine and Jubin, Laetitia and Siria, Alessandro and Bocquet, Lyderic
PHYSICAL REVIEW LETTERS 116 (2016) 
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Abstract : In this Letter, we perform an experimental study of ionic transport and current fluctuations inside individual carbon nanotubes (CNTs). The conductance exhibits a power law behavior at low salinity, with an exponent close to 1/3 versus the salt concentration in this regime. This behavior is rationalized in terms of a salinity dependent surface charge, which is accounted for on the basis of a model for hydroxide adsorption at the (hydrophobic) carbon surface. This is in contrast to boron nitride nanotubes which exhibit a constant surface conductance. Further, we measure the low frequency noise of the ionic current in CNTs and show that the amplitude of the noise scales with the surface charge, with data collapsing on a master curve for the various studied CNTs at a given pH.
Velocity Condensation for Magnetotactic Bacteria - Rupprecht, Jean-Francois and Waisbord, Nicolas and Ybert, Christophe and Cottin-Bizonne, Cecile and Bocquet, Lyderic
PHYSICAL REVIEW LETTERS 116 (2016) 
LPS


Abstract : Magnetotactic swimmers tend to align along magnetic field lines against stochastic reorientations. We show that the swimming strategy, e.g., active Brownian motion versus run-and-tumble dynamics, strongly affects the orientation statistics. The latter can exhibit a velocity condensation whereby the alignment probability density diverges. As a consequence, we find that the swimming strategy affects the nature of the phase transition to collective motion, indicating that Levy run-and-tumble walks can outperform active Brownian processes as strategies to trigger collective behavior.
Activated desorption at heterogeneous interfaces and long-time kinetics of hydrocarbon recovery from nanoporous media - Lee, Thomas and Bocquet, Lyderic and Coasne, Benoit
NATURE COMMUNICATIONS 7 (2016) 
LPS


Abstract : Hydrocarbon recovery from unconventional reservoirs (shale gas) is debated due to its environmental impact and uncertainties on its predictability. But a lack of scientific knowledge impedes the proposal of reliable alternatives. The requirement of hydrofracking, fast recovery decay and ultra-low permeability-inherent to their nanoporosity-are specificities of these reservoirs, which challenge existing frameworks. Here we use molecular simulation and statistical models to show that recovery is hampered by interfacial effects at the wet kerogen surface. Recovery is shown to be thermally activated with an energy barrier modelled from the interface wetting properties. We build a statistical model of the recovery kinetics with a two-regime decline that is consistent with published data: a short time decay, consistent with Darcy description, followed by a fast algebraic decay resulting from increasingly unreachable energy barriers. Replacing water by CO2 or propane eliminates the barriers, therefore raising hopes for clean/efficient recovery.
Active Osmotic Exchanger for Efficient Nanofiltration Inspired by the Kidney - Marbach, Sophie and Bocquet, Lyderic
PHYSICAL REVIEW X 6 (2016) 
LPS


Abstract : In this paper, we investigate the physical mechanisms underlying one of the most efficient filtration devices: the kidney. Building on a minimal model of the Henle loop-the central part of the kidney filtration-we investigate theoretically the detailed out-of-equilibrium fluxes in this separation process in order to obtain absolute theoretical bounds for its efficiency in terms of separation ability and energy consumption. We demonstrate that this separation process operates at a remarkably small energy cost as compared to traditional sieving processes while working at much smaller pressures. This unique energetic efficiency originates in the double-loop geometry of the nephron, which operates as an active osmotic exchanger. The principles for an artificial-kidney-inspired filtration device could be readily mimicked based on existing soft technologies to build compact and low-energy artificial dialytic devices. Such a ``kidney on a chip'' also points to new avenues for advanced water recycling, targeting, in particular, sea-water pretreatment for decontamination and hardness reduction.
Massive radius-dependent flow slippage in carbon nanotubes - Secchi, Eleonora and Marbach, Sophie and Nigues, Antoine and Stein, Derek and Siria, Alessandro and Bocquet, Lyderic
NATURE 537210-213 (2016) 
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Abstract : Measurements and simulations have found that water moves through carbon nanotubes at exceptionally high rates owing to nearly frictionless interfaces(1-4). These observations have stimulated interest in nanotube-based membranes for applications including desalination, nano-filtration and energy harvesting(5-10), yet the exact mechanisms of water transport inside the nanotubes and at the water-carbon interface continue to be debated(11,12) because existing theories do not provide a satisfactory explanation for the limited number of experimental results available so far(13). This lack of experimental results arises because, even though controlled and systematic studies have explored transport through individual nanotubes(7-9,14-17), none has met the considerable technical challenge of unambiguously measuring the permeability of a single nanotube(11). Here we show that the pressure-driven flow rate through individual nanotubes can be determined with unprecedented sensitivity and without dyes from the hydrodynamics of water jets as they emerge from single nanotubes into a surrounding fluid. Our measurements reveal unexpectedly large and radius-dependent surface slippage in carbon nanotubes, and no slippage in boron nitride nanotubes that are crystallographically similar to carbon nanotubes, but electronically different. This pronounced contrast between the two systems must originate from subtle differences in the atomic-scale details of their solid-liquid interfaces, illustrating that nanofluidics is the frontier at which the continuum picture of fluid mechanics meets the atomic nature of matter.
Destabilization of a flow focused suspension of magnetotactic bacteria - Waisbord, Nicolas and Lefevre, Christopher T. and Bocquet, Lyderic and Ybert, Christophe and Cottin-Bizonne, Cecile
PHYSICAL REVIEW FLUIDS 1 (2016) 
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Abstract : Active matter is a new class of intrinsically out-of equilibrium material with intriguing properties. The recent upsurge of studies in this field has mostly focused on the spontaneous behavior of these systems. Yet, many systems evolve under external constraints and driving forces, being subjected to both flow and various taxis. We present a new experimental system based on the directional control of magnetotactic bacteria which enables quantitative investigations to complement the challenging theoretical description of such systems. We explore the behavior of self-propelled magnetotactic bacteria as a particularly rich and versatile class of driven matter, whose behavior can be studied under a range of hydrodynamic and magnetic field stimuli. In particular we demonstrate that the competition between cell orientation toward a magnetic field and hydrodynamic flow lead not only to jetting, but to a new pearling instability. This model system illustrates new structuring capabilities of driven active matter.
Carbon membranes for efficient water-ethanol separation - Gravelle, Simon and Yoshida, Hiroaki and Joly, Laurent and Ybert, Christophe and Bocquet, Lyderic
JOURNAL OF CHEMICAL PHYSICS 145 (2016) 
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Abstract : We demonstrate, on the basis of molecular dynamics simulations, the possibility of an efficient water-ethanol separation using nanoporous carbon membranes, namely, carbon nanotube membranes, nanoporous graphene sheets, and multilayer graphene membranes. While these carbon membranes are in general permeable to both pure liquids, they exhibit a counter-intuitive ``self-semi-permeability'' to water in the presence of water-ethanol mixtures. This originates in a preferred ethanol adsorption in nanoconfinement that prevents water molecules from entering the carbon nanopores. An osmotic pressure is accordingly expressed across the carbon membranes for the water-ethanol mixture, which agrees with the classic van't Hoff type expression. This suggests a robust and versatile membrane-based separation, built on a pressure-driven reverse-osmosis process across these carbon-based membranes. In particular, the recent development of large-scale ``graphene-oxide'' like membranes then opens an avenue for a versatile and efficient ethanol dehydration using this separation process, with possible application for bio-ethanol fabrication. Published by AIP Publishing.
Chemisorption of Hydroxide on 2D Materials from DFT Calculations: Graphene versus Hexagonal Boron Nitride - Grosjean, Benoit and Pean, Clarisse and Siria, Alessandro and Bocquet, Lyderic and Vuilleumier, Rodolphe and Bocquet, Marie-Laure
JOURNAL OF PHYSICAL CHEMISTRY LETTERS 74695-4700 (2016) 
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Abstract : Recent nanofluidic experiments revealed strongly different surface charge measurements for boron-nitride (BN) and graphitic nanotubes when in contact with saline and alkaline water (Nature 2013, 494, 455-458; Phys. Rev. Lett. 2016, 116, 154501). These observations contrast with the similar reactivity of a graphene layer and its BN counterpart, using density functional theory (DFT) framework, for intact and dissociative adsorption of gaseous water molecules. Here we investigate, by DFT in implicit water, single and multiple adsorption of anionic hydroxide on single layers. A differential adsorption strength is found in vacuum for the first ionic adsorption on the two materials-chemisorbed on BN while physisorbed on graphene. The effect of implicit solvation reduces all adsorption values, resulting in a favorable (nonfavorable) adsorption on BN (graphene). We also calculate a pK(a) similar or equal to 6 for BN in water, in good agreement with experiments. Comparatively, the unfavorable results for graphene in water echo the weaker surface charge measurements but point to an alternative scenario.
DOI
10
Origins of Negative Gas Adsorption - Evans, Jack D. and Bocquet, Lyderic and Coudert, Francois-Xavier
CHEM 1873-886 (2016) 
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Abstract : Negative gas adsorption by a porous crystalline solid, DUT-49, observed by spontaneous desorption of gas during a pressure increase raises fundamental questions on the physical origin of this puzzling behavior. Importantly, a framework that can transform a large amount of strain into pressure has many possible technological applications. To address this question, we studied the mechanics and thermodynamics of DUT-49 at both the molecular unit and framework scales by applying quantum density functional theory and extensive classical molecular-dynamics simulations. We demonstrate that negative gas adsorption originates from molecular buckling of the organic structural unit and thus allows a colossal framework transformation. Methane adsorption is subsequently shown to activate this transition, in full agreement with experimental observations. The molecular insight presented here unveils the mechanics and thermodynamics responsible for negative gas adsorption and provides unparalleled understanding to aid the discovery of new examples of similarly responsive porous metamaterials.
 
2015
DOI
11
Ultra-sensitive flow measurement in individual nanopores through pressure - driven particle translocation - Gadaleta, Alessandro and Biance, Anne-Laure and Siria, Alessandro and Bocquet, Lyderic
NANOSCALE 77965-7970 (2015) 
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Abstract : A challenge for the development of nanofluidics is to develop new instrumentation tools, able to probe the extremely small mass transport across individual nanochannels. Such tools are a prerequisite for the fundamental exploration of the breakdown of continuum transport in nanometric confinement. In this letter, we propose a novel method for the measurement of the hydrodynamic permeability of nanometric pores, by diverting the classical technique of Coulter counting to characterize a pressure-driven flow across an individual nanopore. Both the analysis of the translocation rate, as well as the detailed statistics of the dwell time of nanoparticles flowing across a single nanopore, allow us to evaluate the permeability of the system. We reach a sensitivity for the water flow down to a few femtoliters per second, which is more than two orders of magnitude better than state-of-the-art alternative methods.
DOI
12
Optimal permeability of aquaporins: a question of shape? - Gravelle, Simon and Joly, Laurent and Detcheverry, Francois and Ybert, Christophe and Cottin-Bizonne, Cecile and Bocquet, Lyderic
M S-MEDECINE SCIENCES 31174-179 (2015) 
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Abstract : Aquaporins are transmembrane proteins, ubiquitous in the human body. Inserted into the cell membranes, they play an important role in filtration, absorption and secretion of fluids. However, the excellent compromise between selectivity and permeability of aquaporins remains elusive. In this review, we focus on the hourglass shape of aquaporins, and we investigate its influence on water permeability, using numerical calculations and a simple theoretical model. We show that there is an optimum opening angle that maximizes the hydrodynamic permeability, and whose value is close to the angles observed in aquaporins.
13
Phonon modes for faster flow - Bocquet, Lyderic and Netz, Roland R.
NATURE NANOTECHNOLOGY 10657-658 (2015) 
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DOI
14
From Paris to Lyon, and from simple to complex liquids: a view on Jean-Pierre Hansen's contribution - Barrat, Jean-Louis and Biben, Thierry and Bocquet, Lyderic
MOLECULAR PHYSICS 1132378-2382 (2015) 
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Abstract : We present a short perspective on some of the contributions made by Jean-Pierre Hansen to our theoretical understanding of soft matter static structure and dynamics, using the tools developed for simple liquids within the rigorous framework of statistical physics.