Adsorption of polyelectrolyte-nanoparticle systems on silica: influence of ionic strength.

In this work the effect of ionic strength on the adsorption behavior of cationic polyelectrolyte (acrylamide-acrylamidopropyltrimethylammonium chloride) and negatively charged silica particles has been studied by means of ellipsometry. The adsorption of the polyelectrolyte was observed to increase with increasing salt concentration, a behavior typical for polyelectrolytes with a screening-reduced solvency and a nonelectrostatic affinity for the surface. A similar dependence on the ionic strength was observed when studying the electrolyte effect on the nanoparticle adsorption to the preadsorbed polyelectrolyte film, suggesting that the polyelectrolyte surface conformations largely govern the binding capacity of the particles to the surface.

Formation and structure of polyelectrolyte and nanoparticle multilayers: effect of particle characteristics.

The formation and structure of multilayer films containing a cationic polyelectrolyte and anionic silica nanoparticles were studied by means of ellipsometry and atomic force microscopy. Three types of silica particles of different sizes were examined. The density and thickness of the films as well as the adsorption kinetics appear to be strongly dependent on the choice of particle; smaller particles favor the formation of smooth and dense films with a higher content of the inorganic component.

Adsorption of Polyelectrolyte and Nanoparticles at the Silica-Aqueous Solution Interface: Influence of the History of Additions of the Two Components.

The interfacial properties of a mixed system of low-charged cationic polyelectrolyte and silica nanoparticles has been studied by means of ellipsometry. Special attention was devoted to the effect that the order of addition of the two components has on the adsorption behavior of the mixed system. Adsorption on silica was in one case studied after simultaneous addition of the components to the aqueous solution.