Effect of the interaction strength and anisotropy on the diffusio-phoresis of spherical colloids

Wei, Jiachen; Ramírez-Hinestrosa, Simón; Dobnikar, Jure; Frenkel, Daan

doi:10.1039/c9sm02053e

Cited by 5 publications

(7 citation statements)

References 47 publications

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“…It seems likely that the concentration dependence of D O flows is not universal as it is for electrotytes. However, our experiments and model, and the simulations of Wei et al (35), all find a speed that decreases at sufficiently high concentrations and strong attractions. As the speed must tend to zero as the concentration tends to zero, a maximum in speed at some concentration may be common for nonelectrolytes.…”

Section: Discussionsupporting

confidence: 50%

“…Paustian et al (6) measured diffusiophoretic motion at speeds ∼0.1 to 1 µm/s, comparable to those in gradients of electrolytes. Very recent simulation work of Wei et al (35) reports speeds that decrease at high concentrations due to saturation of the interfacial region, but this remains untested experimentally. While the dependence of DP and D O speeds on the concentration gradient is relatively well understood for electrolytes, our understanding is much poorer for neutral solutes.…”

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confidence: 99%

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Diffusioosmotic and convective flows induced by a nonelectrolyte concentration gradient

Williams

Lee

Apriceno

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Glucose is an important energy source in our bodies, and its consumption results in gradients over length scales ranging from the subcellular to entire organs. Concentration gradients can drive material transport through both diffusioosmosis and convection. Convection arises because concentration gradients are mass density gradients. Diffusioosmosis is fluid flow induced by the interaction between a solute and a solid surface. A concentration gradient parallel to a surface creates an osmotic pressure gradient near the surface, resulting in flow. Diffusioosmosis is well understood for electrolyte solutes, but is more poorly characterized for nonelectrolytes such as glucose. We measure fluid flow in glucose gradients formed in a millimeter-long thin channel and find that increasing the gradient causes a crossover from diffusioosmosis-dominated to convection-dominated flow. We cannot explain this with established theories of these phenomena which predict that both scale linearly. In our system, the convection speed is linear in the gradient, but the diffusioosmotic speed has a much weaker concentration dependence and is large even for dilute solutions. We develop existing models and show that a strong surface–solute interaction, a heterogeneous surface, and accounting for a concentration-dependent solution viscosity can explain our data. This demonstrates how sensitive nonelectrolyte diffusioosmosis is to surface and solution properties and to surface–solute interactions. A comprehensive understanding of this sensitivity is required to understand transport in biological systems on length scales from micrometers to millimeters where surfaces are invariably complex and heterogeneous.

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Section: Discussionsupporting

confidence: 50%

mentioning

confidence: 99%

Diffusioosmotic and convective flows induced by a nonelectrolyte concentration gradient

Williams

Lee

Apriceno

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…This is a consequence of the finite Péclet number, which in this case is of the order of Pe≈ vL/D, where v is the average flow velocity, L the distance between the reservoirs, and D the diffusion coefficient of both solute and solvent. As a result, the local concentration gradient at the location of the colloid decreases (see also [44]). Fig.…”

Section: Bd-nemd Resultsmentioning

confidence: 99%

“…More recent simulations have used both equilibrium and non-equilibrium MD techniques to study diffusio-osmosis [27,28,31,46]. In addition, there have been several reports on MD sim-ulations of diffusiophoresis of colloids [38,44] and short polymers [36].…”

Section: Introductionmentioning

confidence: 99%

Challenges in modelling diffusiophoretic transport

Ramírez-Hinestrosa

Frenkel

2021

Eur. Phys. J. B

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The methodology to simulate transport phenomena in bulk systems is well-established. In contrast, there is no clear consensus about the choice of techniques to model cross-transport phenomena and phoretic transport, mainly because some of the hydrodynamic descriptions are incomplete from a thermodynamic point of view. In the present paper, we use a unified framework to describe diffusio-osmosis(phoresis), and we report non-equilibrium molecular dynamics (NEMD) on such systems. We explore different simulation methods to highlight some of the technical problems that arise in the calculations. For diffusiophoresis, we use two NEMD methods: boundary-driven and field-driven. Although the two methods should be equivalent in the limit of very weak gradients, we find that finite Peclet-number effects are much stronger in boundary-driven flows than in the case where we apply fictitious color forces. Graphic abstract

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“…More recent simulations have used both equilibrium and non-equilibrium MD techniques to study diffusio-osmosis [46,27,28,31]. In addition, there have been several reports on MD simulations of diffusiophoresis of colloids [38,44] and short polymers [36].…”

Section: Introductionmentioning

confidence: 99%

Challenges in modelling diffusiophoretic transport

Ramírez-Hinestrosa,

Frenkel

2021

Preprint

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The methodology to simulate transport phenomena in bulk systems is well-established. In contrast, there is no clear consensus about the choice of techniques to model cross-transport phenomena and phoretic transport, mainly because some of the hydrodynamic descriptions are incomplete from a thermodynamic point of view. In the present paper, we use a unified framework to describe diffusio-osmosis(phoresis), and we report non-equilibrium Molecular Dynamics (NEMD) on such systems. We explore different simulation methods to highlight some of the technical problems that arise in the calculations. For diffusiophoresis, we use two NEMD methods: boundary-driven and field-driven. Although the two methods should be equivalent in the limit of very weak gradients, we find that finite Peclet-number effects are much stronger in boundary-driven flows than in the case where we apply fictitious color forces.

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Effect of the interaction strength and anisotropy on the diffusio-phoresis of spherical colloids

Cited by 5 publications

References 47 publications

Diffusioosmotic and convective flows induced by a nonelectrolyte concentration gradient

Diffusioosmotic and convective flows induced by a nonelectrolyte concentration gradient

Challenges in modelling diffusiophoretic transport

Challenges in modelling diffusiophoretic transport

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