FORCES BETWEEN POLYELECTROLYTE COATED SURFACES IN THE PRESENCE OF ELECTROLYTE

The interaction between charged surfaces bearing terminally attached p olyelectrolyte chains is investigated using Monte Carlo computer simul ations and a mean-field theory. In particular we focus on the role pla yed by the addition of a simple electrolyte component. It is found tha t the force between the surfaces increases with increasing electrolyte concentration because of a repulsive osmotic pressure contribution du e to the small ions, while the attractive bridging component is insens itive to added salt. Considering the approximate nature of the mean-fi eld (polyelectrolyte Poisson-Boltzmann) theory it compares well with t he computer simulations.