Interfacial and colloidal properties of cosmetic emulsions containing fatty alcohol and fatty alcohol polyglycol ethers

Abstract

Abstract:The phase behavior of multicomponent systems, especially of emulsions conraining cetostearyl alcohol and fatty alcohol polyglycol ethers has been investigated. At the phase inversion from o/w to w/o emulsions, one-phase regions containing lamellar liquid crystals have been observed. In appropriate ratios of the amphiphiles, extremely low interfacial tensions (~ 10 -3 mN/m) are obtained, which lead to very easy emulsification and narrow particle size distribution. Thermoanalysis (DSC) and microscopy of binary, ternary and quaternary mixtures demonstrate the existence of hydrated crystals or gels at room temperature. Anisotropic phases could be identified around oil droplets of more coarse emulsions. Emulsions prepared at low temperatures possess structural viscosity. Increasing the temperature leads to newtonian behavior. At medium emulsifier concentrations fluid and stable emulsions are obtained. There is a strong dependence of the properties of the emulsions on the polarity of the oil phase. It can be concluded that the ability to form fine droplets, the viscosity and the long term stability of cosmetic emulsions do not depend on the properties of the fatty alcohol alone but on the mixed phases formed by the emulsifier and the alcohol.

Structure and rheology of semisolid o/w creams containing cetyl alcohol/non‐ionic surfactant mixed emulsifier and different polymers

“…With cetyl alcohol, there was a broad endotherm peaking at 51 °C with a broad shoulder from 40 to 50 °C. The broad shoulder probably represented the melting of β and γ crystals and the endotherm peaking at 51 the fusion of the a crystals [3, 19, 20]. The melting of the surfactant crystals (cetyl stearyl alcohol 12 mol EO) occurred at lower temperatures with a broad double endotherm peaking at 34 and 40 °C.…”

Microemulsions in Technical Processes

“…Even more important, however, is that the interfacial tension 0ab reaches a distinct minimum at the mean temperature of the three-phase region T.17 This means that the efficiency of an amphiphile, 1/y, has a maximum at that temperature where the interfacial tension, 0ab, has a minimum, which again underlines the significance of T. The lowest values of 0ab measured at T are in the range of 10-5 mN m-1 for ionic amphiphiles and 10-4 mN m-1 for nonionic amphiphiles.41-43 An example of very low interfacial tensions of a system near T is given in Figure 6. 44 In his paper "Microemulsions-A thermodynamic approach"17 Kahlweit describes the relations between T, 7, and 0ab and shows that the minimum of 0ab is a direct consequence of the temperature-depending form of the three-phase region.…”

“…Interfacial tension between water and oil of a system near T. The system is water, paraffin oil, and a mixture of surfactant and cosurfactant at different ratios at a temperature of 75 °C. 44 The variation of the ratio between surfactant and cosurfactant causes a shift of the mean temperature of the overall system from a temperature above to a temperature below the temperature of the experiments (T = 75 °C).…”

Transdermal solid delivery of epigallocatechin-3-gallate using self-double-emulsifying drug delivery system as vehicle: Formulation, evaluation and vesicle-skin interaction

“…12 It can be related to a polarity increase of lipid phase depend on the concentration of solid lipid. 22 The EE of EGCG-SDEDDS did not change significantly with varying EGCG concentration. However, the increment of EGCG concentration caused a little reduction in the EE.…”