Emulsification by the phase inversion temperature method: the role of self-bodying agents and the influence of oil polarity.

Synopsis Oil-in-water emulsions stabilized with nonionic emulsifiers change to water-in-oil emulsions as the temperature rises when the hydrophilic and lipophilic properties of the mixed emulsifier are just balanced. Preparation above the phase inversion temperature followed by rapid cooling yields emulsions that exhibit very fine droplet size and extreme long-term stability. Cosmetic emulsions were prepared by this phase inversion temperature (PIT) method using typical raw materials such as polar oils, e.g. decyl oleate, 2-octyl dodecanol or isopropyl myristate, and nonionic emulsifiers, e.g. ceteareth-12 or polyoxyethylene eicosyl/docosyl ether combined with cetostearyl alcohol as a co-emulsifier. The phase inversion temperature was measured as a function of the oil polarity and the concentration of mixed emulsifier. The relationship between phase inversion temperature, droplet size and emulsion stability was investigated. In addition, self-bodying agents such as cetostearyl alcohol or monoglycerides were added to these thin, fine disperse emulsions to adjust the consistency. The influence of these ingredients on phase inversion temperature, droplet size, yield value and emulsion stability was studied.