Depletion forces due to image charges near dielectric discontinuities

作者：Curtis Robin A; Lue Leo^*

来源：Current Opinion in Colloid & Interface Science, 2015, 20(1): 19-23.

DOI：10.1016/j.cocis.2014.12.001

• Depletion force
• Dielectric
• Electrolyte
• Colloids

The depletion force is an effective 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 inter-particle 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.

• 出版日期2015-2