Laplace pressure based disjoining pressure isotherm in non symmetric conditions

Huerre, Axel; Valignat, Marie-Pierre; Maggs, A. C.; Théodoly, Olivier; Jullien, Marie‐Caroline

doi:10.1063/1.4997857

Cited by 4 publications

(9 citation statements)

References 23 publications

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“…We first reported experimental evidence of 3D topographies of the lubrication film using a similar experimental set-up in a previous work (Huerre et al (2015)). The present work aims to investigate these 3D geometries more locally.…”

Section: Notes On the Experimentsmentioning

confidence: 99%

“…We chose to use a surfactant (C 10 TAB) that was previously shown to have negligible influence on the boundary condition by Delacotte et al (2012), in similar experimental conditions: same solution (without salt), same capillary range, but larger scale (meniscus size). (iii) In the range of confinement that is investigated using microfluidics, the thin liquid film squeezed between the droplet and the wall may be so thin that intermolecular interactions come into play and may set the lubrication film thickness, Huerre et al (2015). In order to screen the electrostatic contribution of the disjoining pressure, the Debye layers are screened by adding salt in the external phase such that the Debye length is reduced to λ D = 0.2 nm.…”

Section: Notes On the Experimentsmentioning

confidence: 99%

“…In the range of confinement that is investigated using microfluidics, the thin liquid film squeezed between the droplet and the wall may be so thin that intermolecular interactions come into play and may set the lubrication film thickness, Huerre et al (2015). In a static configuration, our experimental set-up can even be used to build disjoining pressure isotherms where the pressure is set by the level of confinement, allowing to investigate high pressures thanks to small cavity thicknesses.…”

Section: Appendix a Determination Of The Film Thickness At The Rear mentioning

confidence: 99%

“…In a static configuration, our experimental set-up can even be used to build disjoining pressure isotherms where the pressure is set by the level of confinement, allowing to investigate high pressures thanks to small cavity thicknesses. The film thickness is measured using RICM, Huerre et al (2017). In these two previous works, the dominant contribution of the intermolecular interaction was due to electrostatic interactions.…”

Section: Appendix a Determination Of The Film Thickness At The Rear mentioning

confidence: 99%

“…These theoretical results were found in good agreement with experimental work ever since Bretherton's early work (Bretherton (1961)), with sometimes discrepancies attributed to additional effects neglected in the model. Recent examples include surfactantcovered bubbles (Denkov et al (2006)) and viscous droplets (Huerre et al (2015)). However, most of these works could only access average quantities over the size of the droplet, since the height of the lubrication film was generally deduced from the velocities of the droplet and external phase, via the conservation of the flow.…”

Section: Introductionmentioning

confidence: 99%

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Topography of the lubrication film under a pancake droplet travelling in a Hele-Shaw cell

et al. 2018

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Understanding the dynamics of a droplet pushed by an external fluid in a confined geometry calls for the identification of all the dissipation mechanisms at play in the lubrication film between droplet and cell wall. Experimentally, reflection interference contrast microscopy has proven an efficient tool to measure the thickness of such lubrication films for microfluidic droplets, with a precision of a few nanometres (Huerre et al., Lab on a Chip, vol. 16 (5), 2016, pp. 911–916). The present work takes advantage of the high accuracy of this technique to chart quantitatively the lubrication film between oil droplets and the glass wall of a microfluidic chamber. We find that the lubrication films exhibit a complex three-dimensional shape, which we are able to rationalize using a hydrodynamical model in the lubrication approximation. We show that the complete topography cannot be recovered using a single model boundary condition along the whole interface. Rather, surface tension gradients are negligible at the front of the droplet, whereas they significantly modify the film profile at the rear, where surfactant accumulation induces local thickening of the lubrication film. The presence of ravines on the sides of the droplet is due to three-dimensional effects which can be qualitatively reproduced numerically. To our knowledge, this is the first experimental investigation of such local effects on travelling droplets.

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Section: Notes On the Experimentsmentioning

confidence: 99%

Section: Notes On the Experimentsmentioning

confidence: 99%

Section: Appendix a Determination Of The Film Thickness At The Rear mentioning

confidence: 99%

Section: Appendix a Determination Of The Film Thickness At The Rear mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Topography of the lubrication film under a pancake droplet travelling in a Hele-Shaw cell

et al. 2018

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Disjoining Pressure of Water in Nanochannels

et al. 2021

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Experiments of water wicking in 1D silicon-dioxide nanochannels of heights 59 nm, 87 nm, 124 nm and 1015 nm are used to estimate the disjoining pressure of water which was found to be as high as ~1.5 MPa while exponentially decreasing with increasing channel height. Such a relation resulting from curve fitting of experimentally-derived data was implemented and validated in computational fluid dynamics. This methodology integrates experimental nanoscale physics into continuum simulations thus enabling the numerical study of various phenomena where disjoining pressure plays an important role. Main TextA nanoscale thin liquid film on a surface can have significantly different properties than its bulk form [1]. At such short distances, intermolecular interactions with surface atoms can dominate and define new equilibrium positions/velocities of liquid atoms; as these fundamental parameters are statistically averaged to estimate thermodynamic properties [2], substantial changes in density, pressure, surface tension, viscosity, etc. can occur. Distances at which a surface can affect liquid properties depends on the atomic composition: if either atom is non-polar, the presence of only weak and short-range van der Waal's force limits such changes to <5 nm [3,4]; however, if both atoms are polar, strong and long-range electrostatic forces can alter properties up to tens to hundreds of nanometers from the surface [5][6][7]. The latter scenario often occurs in practical situations involving water on various surfaces.

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Deposits from evaporating emulsion drops

Bittermann¹,

Deblais²,

Lépinay³

et al. 2020

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The processes in which droplets evaporate from solid surfaces, leaving behind distinct deposition patterns, have been studied extensively for variety of solutions. In this work, by combining different microscopy techniques (confocal fluorescence, video and Raman) we investigate pattern formation and evaporation-induced phase change in drying oil-in-water emulsion drops. This combination of techniques allows us to perform drop shape analysis while visualizing the internal emulsion structure simultaneously. We observe that drying of the continuous water phase of emulsion drops on hydrophilic surfaces favors the formation of ring-like zones depleted of oil droplets at the contact line, which originate from geometrical confinement of oil droplets by the meniscus. From such a depletion zone, a “coffee ring” composed of surfactant molecules forms as the water evaporates. On all surfaces drying induces emulsion destabilization by coalescence of oil droplets, commencing at the drop periphery. For hydrophobic surfaces, the coalescence of the oil droplets leads to a uniform oil film spreading out from the initial contact line. The evaporation dynamics of these composite drops indicate that the water in the continuous phase of the emulsion drops evaporates predominantly by diffusion through the vapor, showing no large differences to the evaporation of simple water drops.

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Laplace pressure based disjoining pressure isotherm in non symmetric conditions

Cited by 4 publications

References 23 publications

Topography of the lubrication film under a pancake droplet travelling in a Hele-Shaw cell

Topography of the lubrication film under a pancake droplet travelling in a Hele-Shaw cell

Disjoining Pressure of Water in Nanochannels

Deposits from evaporating emulsion drops

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