Encapsulation of Fragrance in Aqueous Emulsions by Delaminated Synthetic Hectorite.

Fragrance emulsions are used in many applications in daily life. Since a lot of fragrances are quite volatile substances, their release rate from emulsions is a crucial factor. Since in most cases a mixture of fragrances is applied, the olfactory impression might change over time if the release rates of individual components differ significantly. For such applications, encapsulation with barrier materials is sought to retard release in an unselective manner. Stable fragrance-in-water emulsions were made by applying a synthetic hectorite as Pickering emulsifier which was fixed as a multilayer stack at the oil-water interface by adding poly(ethylene imine). The release of different fragrance molecules (eucalyptol, limonene, α-pinene, and ethyl-2-methylbutyrate) from these emulsions was studied as the ratio between hectorite and poly(ethylene imine) was varied. While the release rates of all fragrances were retarded by the hybrid capsule acting as a nonselective barrier, the relative release was determined by the solubility of individual fragrances in the capsule material. Fragrance release could be further reduced by additional chemical cross-linking of poly(ethylene imine).