Phase behavior and stability of nano-emulsions prepared by D phase emulsification method

Abstract D phase emulsification method was applied to prepare nano-emulsions in the Span 80-Tween 80/glycerin/water/mineral oil system. The phase behavior of this system during the entire emulsification process and the stability of the prepared emulsions were investigated by means of a pseudo-ternary phase experimental design. A possible emulsification mechanism was preliminarily proposed on the basis of our experimental results. It was found that the special self-assembled structure of the D phase and its capability for oil phase were the crucial factors in the D phase emulsification. Firstly, the surfactant alignment of the D phase was beneficial to the formation of small oil droplets in the O/D phase. Then, a quick movement of the surfactants toward the oil-water interface was critical for preparing nano-emulsions. Furthermore, the stability of the nano-emulsions during storage (30 days) was predominantly related to the addition amount of surfactants. The higher the content of surfactant in the system, the more stable the nano-particle interface film was formed. The stable interface film avoids the aggregation of the particles due to the thermal motion of the molecules, and the nano-particles could remain stable during storage.