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Thermodynamic approach to the self-diffusiophoresis of colloidal Janus particles

Thomas Speck
Phys. Rev. E 99, 060602(R) – Published 13 June 2019

Abstract

Most available theoretical predictions for the self-diffusiophoretic motion of colloidal particles are based on the hydrodynamic thin boundary layer approximation in combination with a solvent body force due to a self-generated local solute gradient. This gradient is enforced through specifying boundary conditions, typically without accounting for the thermodynamic cost to maintain the gradient. Here, we present an alternative thermodynamic approach that exploits a direct link between dynamics and entropy production: the local detailed balance condition. We study two cases: First, we revisit self-propulsion in a demixing binary solvent. At variance with a slip velocity, we find that propulsion is due to forces at the poles that are perpendicular to the particle surface. Second, for catalytic swimmers driven through liberating chemical free energy we recover previous expressions. In both cases we argue that propulsion is due to asymmetric dissipation and not simply due to an asymmetric concentration of molecular solutes.

  • Figure
  • Received 27 March 2019

DOI:https://doi.org/10.1103/PhysRevE.99.060602

©2019 American Physical Society

Physics Subject Headings (PhySH)

Fluid DynamicsStatistical Physics & Thermodynamics

Authors & Affiliations

Thomas Speck

  • Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany

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Issue

Vol. 99, Iss. 6 — June 2019

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