Dispersion forces acting between silica particles across water: influence of nanoscale roughness.

Force profiles between pairs of silica particles in concentrated aqueous solutions of a monovalent salt are measured using atomic force microscopy (AFM). Under such conditions, the double layer forces are negligible, and the profiles are dominated by van der Waals dispersion forces at larger distances. Heat treatment of the particles strongly influences the strength of dispersion forces.

Forces between silica particles in the presence of multivalent cations.

Forces between negatively charged silica particles in aqueous electrolyte solutions were measured with the colloidal probe technique based on the atomic force microscope (AFM). The present study focuses on the comparison of monovalent and multivalent counterions, namely K(+), Mg(2+), and La(3+). The force profiles can be well described with the theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO) down to distances of about 4 nm.

Forces between different latex particles in aqueous electrolyte solutions measured with the colloidal probe technique.

In this article, a compilation of results on direct force measurements between colloidal particles in monovalent salts carried out with the colloidal probe technique based on Atomic Force Microscopy was presented. The interaction forces between similar and dissimilar particles was studied and it was concluded that, in general, these force profiles may be satisfactorily quantified by the DLVO theory down to distances of few nanometers. However, in the specific case where the charge of one of the involved particle is close to neutral, it was found that the surface potential of this particle may change its sign depending on the sign of charge of the opposite particle.

Long-ranged and soft interactions between charged colloidal particles induced by multivalent coions.

Forces between charged particles in aqueous solutions containing multivalent coions and monovalent counterions are studied by the colloidal probe technique. Here, the multivalent ions have the same charge as the particles, which must be contrasted to the frequently studied case where multivalent ions have the opposite sign as the substrate. In the present case, the forces remain repulsive and are dominated by the interactions of the double layers.

Measurements of dispersion forces between colloidal latex particles with the atomic force microscope and comparison with Lifshitz theory.

Interaction forces between carboxylate colloidal latex particles of about 2 μm in diameter immersed in aqueous solutions of monovalent salts were measured with the colloidal probe technique, which is based on the atomic force microscope. We have systematically varied the ionic strength, the type of salt, and also the surface charge densities of the particles through changes in the solution pH. Based on these measurements, we have accurately measured the dispersion forces acting between the particles and estimated the apparent Hamaker constant to be (2.

Photocatalytic activity of titanium dioxide modified by silver nanoparticles.

Photocatalytic activity of Ag/TiO(2) composites obtained by photoreduction treatment (PRT) was investigated. The composite materials, containing various ratio of silver nanoparticles (0.6-3.