Interaction between charged colloids in a low dielectric constant solventE. Allahyarov1, 2, E. Zaccarelli3, F. Sciortino3, P. Tartaglia4 and H. Löwen1
1 Institut für Theoretische Physik, Heinrich-Heine-Universität Düsseldorf - D-40225 Düsseldorf, Germany
2 Institute for High Temperatures, Russian Academy of Sciences - Izhorskaya 13/19, 117419 Moscow, Russia
3 Dipartimento di Fisica and CNR-INFM-SOFT, Università di Roma La Sapienza - P.le A. Moro 2, I-00185 Roma, Italy
4 Dipartimento di Fisica and CNR-INFM-SMC, Università di Roma La Sapienza - P.le A. Moro 2, I-00185 Roma, Italy
received 9 December 2006; accepted in final form 21 March 2007; published May 2007
published online 17 April 2007
Based on computer simulations of the primitive model of electrolytes, we show that the effective interaction between low-charge colloids in solvents of low or moderate dielectric constant depends crucially on the salt concentration. While in the absence of salt the interaction is repulsive in agreement with Derjaguin-Landau-Verwey-Overbeek theory, depletion of salt Bjerrum pairs around the colloids leads to an attraction between like-charge colloids even at small salt concentrations.
82.70.Dd - Colloids.
61.20.Qg - Structure of associated liquids: electrolytes, molten salts, etc..
87.15.Aa - Theory and modeling; computer simulation.
© Europhysics Letters Association 2007