Preparation of counterion stabilized concentrated silver sols.

A strategy for obtaining stable concentrated silver dispersions without dedicated stabilizing agents is presented. This approach consists of rapidly mixing aqueous solutions of silver salicylate and ascorbic acid. By using salicylate as Ag(+) counterion, it is possible to prepare stable sols with metal concentrations up to two orders of magnitude higher than with silver nitrate. The stabilizing effect of the counterion is the result of a decreased ionic strength due to salicylate protonation and its adsorption on the surface of silver. Both effects increase the range of the electrostatic repulsive forces by expanding the electrical double layer.