On the bulk modulus of the cell model of charged macromolecules suspensions

Abstract

We study theoretically the bulk modulus (inverse of the compressibility) of a suspension of charged objects (macro-ions), making use of a cell model to account for the finite density of macro-ions. The diffuse layer of charged micro-species around a macro-ion is described by a generic local density functional theory. Within this general framework, we obtain the condition for a positive bulk modulus, which is fulfilled by several proposals made in the literature and rules out the possibility of a critical point. We show that a sufficient condition for a positive compressibility also ensures that the same theory produces repulsive effective pair potentials.

References in corpus (4)

• Steric Effects in Electrolytes: A Modified Poisson-Boltzmann Equation
• Ion-ion correlations: an improved one-component plasma correction
• Effective interactions between like-charged macromolecules
• A Wigner-Seitz model of charged lamellar colloidal dispersions

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• A density functional theory study of electric potential saturation: planar geometry
• The contact theorem for charged fluids: from planar to curved geometries
• Electroneutrality and Phase Behavior of Colloidal Suspensions
• Screening of Spherical Colloids beyond Mean Field -- A Local Density Functional Approach