INFLUENCE OF MICROEMULSION PHASES ON THE PREPARATION OF FINE-DISPERSE EMULSIONS

Emulsions which are used in cosmetics and for technical applications must fulfil certain requirements concerning fine-dispersity and long-term stability. In practice, besides mechanical energy input the phase behavior of the emulsion system may be utilized to obtain optimal emulsification results. Oil-in-water emulsions stabilized with nonionic emulsifiers can show a temperature induced phase inversion from an oil-in-water to a water-in-oil type. During phase inversion often a microemulsion phase is passed which is connected with ultralow interfacial tensions between the oily and aqueous phase. Due to this ultralow interfacial tension finely dispersed emulsions with long-term stability can be produced by phase inversion emulsification without high energy input. The review presents important basic properties of the fatty alcohol ethoxylates in oil/water systems and their effects on the emulsifying behavior. By a systematic study of emulsion and microemulsion phase behavior certain rules have been established which allow the preselection of optimal emulsification routes and optimal emulsifier/oil combinations. On the basis of these rules an algorithm is described, which is used for the calculation of optimal emulsified mixtures for cosmetic and technical emulsions.