Resumo

HRIBAR, Barbara  e  VLACHY, Vojko. Properties of Polyelectrolyte Solutions as Determined by the Charge of Counterions. Rev. Soc. Quím. Méx [online]. 2000, vol.44, n.1, pp.11-15. ISSN 0583-7693.

Several experimental results published in the last decade are clearly inconsistent with the classical DLVO theory of colloid stability. These experiments are supported by theoretical studies suggesting the existence of an attractive force between equally charged macroions which is not of van der Waals origin. This paper is a part of an ongoing project applying computer simulations to understand the basic properties of highly asymmetric electrolytes. The primitive model for −12/+1, −12/+2, and −12/+3 electrolyte solutions was examined using the canonical Monte Carlo method. The results show, in agreement with previous studies, that the valency of counterions plays a crucial role in determining the structural and thermodynamic properties of polyelectrolyte solutions. In solutions with trivalent counterions the equally charged macroions form clusters that are stable against dilution and are not substantially affected by addition of a neutral component. Also, a relatively large concentration of added simple electrolyte is needed to modify the structure of the solution and to partly 'dissolve' the clusters. The strong correlations among ions in solutions with divalent or trivalent counterions are also reflected in low values of the osmotic coefficient.

Palavras-chave : Polyelectrolytes; computer simulations; colloids; ion-ion correlations; structural properties; thermodynamics.