Cosmetics and personal care applications

Because of their excellent carrier properties, dendrimers have utility in cosmetics and personal care products such as hair-styling gels, shampoos, sunscreens, and anti-acne products. Cosmetic compositions comprising hydroxyl-functionalized dendritic macromolecules are described in a patent filed by Unilever's Home & Personal Care division for application in a hair-styling spray, gel, or mousse formulation (45). The dendritic macromolecules indicated for the hairstyling application in this patent use the polyhydric polyester alcohol or hyperbranched polyol functionalized groups. Another patent filed by L'Oreal described terminal hydroxyl functional group polyester dendritic macromolecules in combination with film-forming polymers for use in cosmetic and dermatological products intended for application to the skin, keratinous fibers, nails, or mucous membranes (46). Such a combination of a film-forming polymer with a dendritic polymer allowed the inventors to develop a low-viscosity product that was easily applied to the intended topical skin site and that formed a dry film capable of being peeled-off after the application period. This property allowed for superior cosmetic product performance and ease of use. Here, the unique ability of dendrimers to form lower viscosity solutions was used to the advantage of the formulation chemist.

Surface modifications of dendrimers have been used as molecular-carrying systems. For example, dendrimers containing at least one free amino group have been used to carry anti-acne agents in a patent filed by Revlon consumer products (47). A keratolytic or anti-acne agent was complexed with a carrying molecule such as a dendrimer containing free amino groups to obtain cosmetically acceptable formulations for treatment of acne vulgaris. In another example of a dendrimer-molecule conjugate system, coupling of aminobutadiene with an amine-rich dendritic molecule provided advantageous UV-absorbing capabilities to the final product (48). This high-molecular-weight dendrimer-aminobutadiene-complexed molecule allowed ease in formulating a clear sunscreen composition without developing high-viscosity gels, which in turn provided ease of application to the skin. Because of the high molecular weight of the resulting molecule, it was nonpenetrating into the skin, which would minimize risk of irritation or sensitization reactions while acting as a UV-light absorber when applied on the skin's surface. In another application, amine-terminated cationic dendrimers have been used in personal-care cleansing compositions as mildness agents (49). Linear cationic polymers used as mildness agents usually precipitate in the presence of anionic surfactants, which reduces their lathering, skin conditioning, or cleansing effects. Dendrimers, on the other hand, are capable of interacting favorably and can bind with anionic surfactants in the composition to remain dispersed in salt solutions. This interaction of cationic dendrimers with skin-irritating anionic surfactants could potentially be used by the personal care chemist for reducing the skin irritation potential of cosmetic formulations containing harsh anionic surfactants.