Stability of orange oil/water nanoemulsions prepared by the PIT method.

This article reports the preparation and characterization of orange oil/water nanoemulsions stabilized by commercial nonionic surfactants based on ethoxylated lauryl ether (Ultrol line), by the phase inversion temperature (PIT) method. The orange oil/surfactant/water dispersions were prepared at different HLB values, by varying the concentrations of the surfactants as well as the concentration of the oil phase. The stability of the o/w nanoemulsions and the size distribution of the dispersed particles in these systems in general depended on the concentration of the oil phase used: the emulsions prepared with an oil phase of 14 wt% had smaller droplet size in the dispersed phase than the emulsions prepared in the presence of oil phases of 20 and 30 wt%. The nanoemulsions prepared with pure surfactants were more stable in the presence of Ultrol L60, but the surfactants' cloud point had a strong influence on the stability of the emulsions formed when this was very near room temperature. Because of this, we prepared systems containing mixtures of surfactants. Among these systems, the most stable nanoemulsions were those prepared with a Ultrol L100/Ultrol L20 mixture with HLB of 12.40. This behavior can be attributed to the complete solubilization in mixed micelles of the more hydrophobic surfactant.