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

Gradients in temperature, concentration or electrostatic potential cannot exert forces on a bulk fluid; they can, however, exert forces on a fluid in a microscopic boundary layer surrounding a (nano)colloidal solute, resulting in so-called phoretic flow. Here we present a simulation study of phoreti...

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Bibliographic Details
Published in:Soft matter 2020-04, Vol.16 (15), p.3621-3627
Main Authors: Wei, Jiachen, Ramírez-Hinestrosa, Simón, Dobnikar, Jure, Frenkel, Daan
Format: Article
Language:English
Subjects:
Anisotropy
Boundary layers
Colloids
Concentration gradient
Electrostatic properties
Flow velocity
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Summary:Gradients in temperature, concentration or electrostatic potential cannot exert forces on a bulk fluid; they can, however, exert forces on a fluid in a microscopic boundary layer surrounding a (nano)colloidal solute, resulting in so-called phoretic flow. Here we present a simulation study of phoretic flow around a spherical colloid held fixed in a concentration gradient. We show that the resulting flow velocity depends non-monotonically on the strength of the colloid-fluid interaction. The reason for this non-monotonic dependence is that solute particles are effectively trapped in a shell around the colloid and cannot contribute to diffusio-phoresis. We also observe that the flow depends sensitively on the anisotropy of solute-colloid interaction. We study gradient-driven diffusio-phoretic flow around a fixed colloid. The flow enabled by the colloid-solute attraction depends sensitively on the interaction strength and anisotropy. The strength dependence is non-monotonic due to trapping of the solute particles around the colloid.
ISSN:1744-683X
1744-6848
DOI:10.1039/c9sm02053e