Silicone surfactants in aqueous solution

The surface and colloid-chemical behaviour of some non-ionic silicone surfactants in water was studied by surface tension, viscosity, dye solubilization, cloud point and light scattering (static and dynamic) measurements over a temperature range of 20-60°C While surface tension data reveal that silicone surfactants possess high surface activity, the viscosity results showed their micelles were spherical. Light scattering studies yielded the micelle aggregation number and hydrodynamic radius which showed a gradual increase with increasing temperature. These results also indicated a low polydispersity in hydrodynamic micelle size. The micellar and solubilizing behaviour of surfactants was dependent on the magnitude of hydrophilic (polyethylene oxide) and hydrophobic (polydimethyl siloxane and/or polypropylene oxide) moieties of the surfactants. The cloud points of the silicone surfactant solutions changed in the presence of electrolytes (KI, KCNS, KBr, KCl, KF) and showed a behaviour similar to the conventional non-ionic surfactants.