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Oléagineux, Corps Gras, Lipides. Volume 11, Number 6, 448-53, NOVEMBRE-DÉCEMBRE 2004, Actifs lipidiques, excipients et formulations cosmétiques

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Author(s) : Jean-Thierry Simonnet, Pascal Richart, Odile Aubrun, Florence L’alloret

Summary : Nanocapsules (submicron particles, of diameter 250 nm, with an oily core enclosed in a solid polymeric shell) were prepared using a controlled nanoprecipitation process with preformed polymers (for example poly-ε caprolactone, polyethylene adipate). Nanocapsules formed by this method contain up to 7.5% oil (1% polymer). The following properties are observed using nanocapsules : improved oxygen stability of active ingredients (retinol, β carotene), significantly improved vectorisation (up to 3 times) in skin and a reservoir effect. Due to their solid polymer shell nanocapsules are stable when formulated and penetrate intact into the superficial layers of the epidermis. Nanoemulsions wich are very fine oil-in-water dispersions having droplet diameter smaller than 100 nanometers, were prepared with a high shear device. Two major sources of unstability were identified and extensively studied: Ostwald ripening and depletion induced floculation following the addition of thickening polymers. The control of these two mechanisms allowed the industrial production of a large variety of cosmetic products. The nanoemulsions are easily valued in skin care due to their good sensorial properties and their biophysical properties.

Keywords : nanoemulsions, Ostwald ripening, depletion, nanocapsules, nanoprecipitation, vectorisation