Formation of wax walled microcapsules via double emulsion using cross membrane emulsification at elevated temperatures

Abstract

A novel micro encapsulation process has been developed via a double emulsion of water in oil in water, whereby the oil is molten during the process and is then solidified to form a solid wall afterwards. This has the potential for an improved encapsulation technique for hydrophilic components. A range of materials was used, including hexadecane, lanolin and cetyl palminate. Temperature controlled, cross membrane emulsification was used to ensure a narrow size distribution. Calculations of permeability, based on the leakage of fluorescein solutions, indicated a much higher rate that would be expected from such a hydrophobic, crystalline wall. Faster cooling gave rise to higher permeability. These suggest that pores are forming in thin walls during the solidification process and indicate the importance of process conditions on wall formation. Osmotic pressure differences are also a potential contributor.