The Correlation between Phase Inversion Temperature In Emulsion and Cloud Point in Solution of Nonionic Emulsifier

Abstract

A model has been advanced in which it is proposed to regard the cloud point in solution of nonionic agent as akin to the phase inversion temperature in emulsion. In the latter, the mixing is macroscopic, whereas in the former the mixing is microscopic or on the bimolecular leaflet scale and the agent serves as an oil as well as an emulsifier. Phase inversion temperatures in hydrocarbon-water emulsions stabilized with polyoxyethylene alkyl phenyl ether have been determined for different hydrocarbons as a function of emulsifier concentration. It was found that the more soluble the hydrocarbon for a noionic emulsifier, the lower is the phase inversion temperature, above which O/W type emulsions invert to W/O type. A similar rule, that the more soluble the nonionic emulsifier for a definite hydrocarbon, the lower the phase inversion temperature, also holds. The effect of polyoxyethylene chain length and hydrocarbon chain length of the emulsifier on the phase inversion temperature have been studied. It was found that the cloud points in solutions of noionic emulsifiers saturated with various hydrocarbons and the phase inversion temperatures in emulsions were parallel, which supports the present model. The effect of temperature on the emulsion stability in connection with the phase inversion temperature is briefly discussed.