(191w) Destabilization of Double Emulsions by Evaporation

Double-emulsion formulations
have a compartmentalized structure that can provide high capacity of
entrapment, protection of fragile substances, combination of incompatible
substances in one product, and controlled release.  We successfully prepared double emulsions with cyclomethicone as
volatile oil phase using a two-step emulsification method, encapsulating model
macromolecules.  Several surfactants (Abil^® EM90, Abil^®
Care 85, and Tween 80) were used to stabilize the double emulsion structure and
TEGO^®Carbomer 341 ER thickener was added to
reach a viscosity ratio that allowed  optimal formation of double-emulsion globules.  The bulk stability of double emulsions was
studied and the most stable formulations were selected to induce
destabilization of thin films by evaporation.  Microstructure of double emulsion films was
monitored during volatilization using optical and fluorescence microscopy.  Thermogravimetric analysis
of double emulsions was performed to study the evaporation mechanism. The
understanding of the evaporation mechanism exhibited in volatile
double-emulsion formulations is important for the controlled release of active
substances involving applications of interest for cosmetic or pharmaceutical industries.