On the macroion virial contribution to the osmotic pressure in charge-stabilized colloidal suspensions

E. Trizac 1, 2, L. Belloni 3, J. Dobnikar 4, 5, H. H. von Grunberg 4, R. Castaneda-Priego 6

Physical Review E: Statistical, Nonlinear, and Soft Matter Physics 75 (2007) 011401

Our interest goes to the different virial contributions to the equation of state of charged colloidal suspensions. Neglect of surface effects in the computation of the colloidal virial term leads to spurious and paradoxical results. This pitfall is one of the several facets of the danger of a naive implementation of the so called One Component Model, where the micro-ionic degrees of freedom are integrated out to only keep in the description the mesoscopic (colloidal) degrees of freedom. On the other hand, due incorporation of wall induced forces dissolves the paradox brought forth in the naive approach, provides a consistent description, and confirms that for salt-free systems, the colloidal contribution to the pressure is dominated by the micro-ionic one. Much emphasis is put on the no salt case but the situation with added electrolyte is also discussed.

  • 1. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS),
    CNRS : UMR8626 – Université Paris XI - Paris Sud
  • 2. Center for Theoretical Biological Physics (CTBP),
    University of San Diego
  • 3. Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire, Service de Chimie Moléculaire,
    CEA
  • 4. Institut für Chemie,
    Karl-Franzens-Universität
  • 5. Jozef Stefan Institute,
    Jozef Stefan Institute
  • 6. Instituto de Fisica,
    Universidad de Guanajuato