The action of hydrophilic substances such as starch and gelatin as well as some proteins in stabilizing hydrophobic dispersions (e.g., Faraday’s famous gold sols) was known in the early days of colloid science. The protective action by adsorbed polymer layers is referred to as “steric stabilization,” which acts by preventing the approach of the particles to a distance where their mutual van der Waals attraction would be sufficient for aggregation to occur. This is in distinction from “charge stabilization” resulting from overlapping of the electrical double layers around the particles. In practice, both the steric and charge mechanisms may operate simultaneously, especially in aqueous systems. In most nonaqueous dispersions, the charge component is insufficient to give adequate stabilization, particularly at high solid concentrations, so that the steric component becomes dominating. The stabilizing effect of polymers in colloidal systems is directly related to their adsorption on the particle surface and the structure of the adsorbed layers formed. As a result of polymer adsorption, the properties of the interface and the intensity of interaction between the surface and intermicellar liquid are radically changed. This leads to a modification of the existing forces or to an appearance of new forces governing the stability of disperse systems; often both effects are manifested.
|Title of host publication||Nanoscience|
|Subtitle of host publication||Colloidal and Interfacial Aspects|
|Number of pages||30|
|Publication status||Published - Jan 1 2010|
ASJC Scopus subject areas