Preparation and characterization of multiple emulsions (W/Si/W) by single-step emulsification

Multiple W/Si/W emulsions were prepared by a single-step emulsification process. The investigated formulations were characterized and the stability over time was evaluated, meanwhile the dynamic and oscillatory rheological properties with different emulsifier concentrations were studied. The multiple structure of W/Si/W emulsion was formed due to favorable interaction between the silicone molecule and the emulsifier molecule. The multiple structure of emulsion with the right ratio of emulsifier exhibited good stability during the aging at different temperatures. In this paper, the emulsion systems with high emulsifier concentrations exhibiting a significant yield stress contributed to form multiple structure emulsion. All prepared samples showed shear-thinning behavior, i.e. the apparent viscosity decreases with the increasing of shear rate. In presence of the highest concentration of emulsifier, the emulsion exhibited the highest viscosity at low shear rate. This study was carried out to reveal possible influence of emulsifier and oil on the multiple emulsions structure, and showed that the influence of the emulsifier was not only observed on formation of multiple emulsion structure but also on the rheological properties.