E-mail: maofukukuyama tohoku. E-mail: mizuguti kit. E-mail: hibara. Spontaneous emulsification is a phenomenon that forms nanometer-sized droplets nanodroplets without the application of any external force, and the mechanism has been actively studied for application to various technologies.
In this study, we analyzed the kinetics of spontaneous emulsification induced by Span The measurement of water concentration in Span 80 hexadecane solution indicated that the chemical potential of water in the nanodroplets decreased as the amount of water in the nanodroplets decreased. Based on this result, water transport between the aqueous phase and nanodroplets in which the chemical potential of water was controlled was quantitatively investigated by using a microfluidic device.
The results demonstrate that the kinetics of water transport during spontaneous emulsification induced by Span 80 was described by a model of osmotic transport through an organic liquid film between the aqueous phase and nanodroplets. Akihide Hibara. Understanding the mechanism of spontaneous emulsification is important for industrial applications. There are several surfactants used for spontaneous emulsification, such as Aerosol-OT, 18 trimethyloctadecylammonium bromide, 15,16 Tween series 3 and Brij series.
Several types of mechanisms have been reported based on ultralow interfacial tension, 2,20 solubility changes, 21 phase transition of the organic phase 11,16 and the interface induced by temperature changes. The spontaneous emulsification of Span 80 does not follow the aforementioned mechanisms but is considered to be driven by the difference in the chemical potential between the aqueous phase and nanodroplets via a water film transport Fig.
As a result, various microdroplet manipulations such as protein crystallization 6 and immunoassay were demonstrated. Understanding the kinetics of spontaneous emulsification is important for its practical use because it is a non-equilibrium, non-stationary phenomenon in which droplets form at the oilβwater interface under transiently changing conditions.
