Depletion forces due to image charges near dielectric discontinuities

Robin A. Curtis, Leo Lue

Research output: Contribution to journalLiterature reviewpeer-review

13 Citations (Scopus)
187 Downloads (Pure)


The depletion force is an eective inter-particle attractive interaction that is entropically driven by the exclusion of co-solvent molecules. For large co-solvents, such as polymers, the exclusion is primarily driven by excluded volume interactions. However, the exclusion of co-solvents, such as electrolytes, can be caused by other mechanisms. In this review, we summarize the literature on interparticle depletion forces that arise from repulsive image-charge forces between low-dielectric particles and electrolytes. In particular, we emphasize the results from a variational perturbation theory for describing the salting-out behavior observed in moderately concentrated salt solutions. The theory predicts an unscreened force with a range given by the Bjerrum length and a magnitude
proportional to the osmotic pressure of the salt solution. The force becomes significant at the same salt concentration where salting-out behavior is typically observed.
Original languageEnglish
Pages (from-to)19-23
Number of pages5
JournalCurrent Opinion in Colloid and Interface Science
Issue number1
Early online date13 Dec 2014
Publication statusPublished - Feb 2015


  • depletion forces
  • dielectric
  • electrolyte
  • colloids


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