A Study on Phase Inversion Temperature Emulsification

Abstract

The combination of an emulsifier and an emollient often decides particle size of the emulsion obtained and its storage stability. In the present report emulsions were assembled according to the CAPICO method developed by Foerster et al. and were subjected to measurement of particle size by means of particle analyzer, SALD 2000A, Shimazdu. Alkylethoxylates were employed as emulsifiers and covered structures of C-chain length, 12-22 and number of ethylene oxide units, 10-20. Emollients covered structures of hydrocarbons, alkylether, mono-, di- and triesters. The ratio of emulsifiers/emollient/water was 1:3:6 w/w/w. Phase inversion temperature was set between 65-85°C by the calculation. In order to meet this temperature a 1:1 emollient mixture was chosen with one part always cetyl octanoate or hexadecane and the second emollient selected from the collection described above. As the third components glycerol, 1, 3-butyleneglycol, propyleneglycol, ethyl alcohol, and ascorbyl phosphate magnesium salt were selected. Particles with less than 100nm in diameter were always generated regardless of emulsifier structure when isopropyl myristate was used in emulsion. Emollients and emulsifiers, both having low or high inorganic character were a good combination for making fine particles. On the other hand, combination of emulsifiers with 20EO plus emollients of low inorganic character or combinations with 10EO plus emollients of high inorganic character produced very large particles. Storage stability test is also carried out to confirm the correlation to the particle size.