An atomic force microscope has been used to investigate the interaction forces between a mica surface and a colloidal glass sphere in the presence of a high molecular weight cationic polyelectrolyte, and the anionic surfactant sodium dodecylbenzenesulfonate (SDbS). The effect of addition of SDbS on the interaction forces between the polyelectrolyte coated surfaces was investigated. At low concentrations of SDbS the electrostatic repulsion initially present was progressively neutralized as a function of increasing surfactant concentration. Neutralization resulted in a strong attraction between the surfaces. As the SDbS concentration was increased further, additional surfactant association took place and the surfaces were recharged. At these surfactant concentrations the surfaces became less attractive at small separations. At high SDbS concentrations the interaction profile became purely repulsive as the surfaces were recharged. Diffuse double layer potentials derived from the direct force measurement data correlated well with zeta-potential measurements of silica particles treated with the polyelectrolyte and surfactant. Particulate stability behaviour was also seen to compare well with the force measurement and electrostatic potential data.
|Number of pages||10|
|Journal||Colloids and Surfaces A: Physicochemical and Engineering Aspects|
|Publication status||Published - 15 Sep 1999|
|Event||Proceedings of the 1997 10th Australian Conference on Colloid and Surface Chemistry - Gold Coast, QLD, Aust|
Duration: 30 Sep 1997 → 3 Oct 1997