Interfacial and emulsifying properties of chitosan/sodium lauryl ether sulfate system

Abstract

Many pharmaceutical, cosmetic and chemical products exist in form of emulsions. A common problem with emulsions is their instability. Interaction between polymer and surfactant could change the adsorption layer around the oil droplets in emulsion which affects their stability. In order to understand the stabilization mechanism, the interface of oil/water systems that contained mixtures of chitosan (Ch), cationic polyelectrolyte and oppositely charged anionic surfactant, sodium lauryl ether sulfate (SLES) was studied by measuring the interfacial tension. Considering the fact that the properties of the oil phase influence the adsorption process, three different types of oil were investigated: medium-chain triglycerides (semi-synthetic oil), paraffin oil (mineral oil) and natural oil obtained from the grape seed. Based on the results of the measurements of interfacial tension, system medium-chain triglycerides/water was selected, for obtaining the 20% oil-in-water (O/W) emulsions. Emulsions were stabilized by Ch/SLES mixture, in mass ratios that correspond to different regions of their interaction. Also investigation on the emulsions characteristics (stability, droplet size and size distribution, zeta potential) was carried out. Results of this study are important for understanding the influence of polymer-surfactant interactions on the properties of solution and stability of dispersed systems that could be useful in microencapsulation processes.