Attraction between identical colloidal particles caused by collective electrostatic repulsion

The goal of this article is threefold: (i) To demonstrate that, within the framework of the Poisson–Boltzmann equation, the interparticle electrostatic interaction in a system containing only two identical particles immersed in an infinite or finite size reservoir of an electrolyte solution is repulsive at all distances. It cannot lead to a short-range repulsion and a long-range attraction as suggested by Sogami and Ise. (ii) To explain Iseʹs experimental observations that the electrostatic interactions in systems containing many identical colloidal particles can lead to attraction. (iii) To note that an effective attraction between two neighboring particles can be generated by the DLVO pair repulsion exerted on them by all the other particles of the system.