Micelles and Nanoemulsions

Abstract

Nanoemulsions and block copolymer micelles have specific features that are make them quite attractive for their application in cosmetic products. Both of them are organic nanoparticles having a liquid core. They are made from the same ingredients as classical emulsions, and their overall organization is also the same. Only the droplet size is smaller by a factor of 10 to 100. The chapter first gives a presentation of the physical chemistry of nanoemulsions and block copolymer micelles, then a discussion of the consequences of the small size to properties focusing on skin absorption. The sub-micron size brings about new properties such as accelerated skin delivery of active substances, absence of creaming in fluid products, immediate skin occlusion, transparency, and gloss after spreading. On the one hand, they are used as drug carriers for topical administration. On the other hand, fast occlusion of skin provides an immediate feeling which is a benefit in moisturizing products. Such properties are discussed with some help of studies carried out for pharmaceutical applications. Their current and prospective implementations in cosmetic technologies are addressed. Finally, the possible safety issues related to the size in the nano-scale are discussed on technical grounds.