(510a) Invited Talk: Nanostructured Surface Treatments Enable the Formulation of Nano-Particulates and Acrylate-Based Polymers in Cosmetic Applications

Modern skin care formulations must meet high standards of efficacy, skin compatibility and aesthetic appeal. The performance of a cosmetic product is related to the entire formulation and an optimal galenic formulation that incorporates active ingredients is a necessary prerequisite to succeed in the market.

ZnO and TiO2 are active ingredients in OTC suncare product. However problems are encountered when these particulates are formulated with charged organic moieties, such as acrylate-based polymers, α- and β-hydroxy acids, etc. Because contemporary skin care formulations are emulsions, the charged organic moieties will reside in the aqueous phase and the inorganic particulates will reside in the oil phase of the emulsion. In formulation the acrylate-based polymers, once neutralized, chain extend to thicken the formulation by increasing the viscosity of the aqueous phase. Other charged organic moieties, such as α- and β-hydroxy acids, may have other functions such as enhancing epithelial cell regeneration.

However ions from the nano-particulates migrate from the oil phase to the aqueous phase and adversely interact with the charged organic moieties to either cause collapse of the acrylate-based polymers or form organic salts with concomitant dissolution of the inorganic particulate.

A new nanostructured surface treatment that passivates nano-particulates and enables their use in formulations containing charged organic moieties will be reported. The surface treatment is a looped, star-graft siloxane copolymer. The nano-structured surface treatment will be described, formulation guidance given, and formulation efficacy will be compared with state-of-the-art products.