Perils of ad hoc approximations for the activity function of chemically powered colloids

  • M. N. Popescu
  • W. E. Uspal
  • M. Tasinkevych
  • S. Dietrich
Regular Article

DOI: 10.1140/epje/i2017-11529-1

Cite this article as:
Popescu, M.N., Uspal, W.E., Tasinkevych, M. et al. Eur. Phys. J. E (2017) 40: 42. doi:10.1140/epje/i2017-11529-1
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Abstract.

Colloids can achieve motility by promoting at their surfaces chemical reactions in the surrounding solution. A well-studied case is that of self-phoresis, in which motility arises due to the spatial inhomogeneities in the chemical composition of the solution and the distinct interactions of the solvent molecules and of the reaction products with the colloid. For simple models of such chemically active colloids, the steady-state motion in an unbounded solution can be derived analytically in closed form. In contrast, for such chemically active particles moving in the vicinity of walls, the derivation of closed-form and physically intuitive solutions of the equations governing their dynamics turns out to be a severe challenge even for simple models. Therefore, recent studies of these phenomena have employed numerical methods as well as approximate analytical approaches based on multipolar expansions. We discuss and clarify certain conceptual aspects concerning the latter type of approach, which arise due to ad hoc truncations of the underlying so-called activity function, which describes the distribution of chemical reactions across the surface of the particle.

Graphical abstract

Keywords

Soft Matter: Colloids and Nanoparticles 

Copyright information

© EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2017

Authors and Affiliations

  • M. N. Popescu
    • 1
    • 2
  • W. E. Uspal
    • 1
    • 2
  • M. Tasinkevych
    • 1
    • 2
  • S. Dietrich
    • 1
    • 2
  1. 1.Max-Planck-Institut für Intelligente SystemeStuttgartGermany
  2. 2.IV. Institut für Theoretische PhysikUniversität StuttgartStuttgartGermany

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