The Role of Surfactants in Sunscreen Formulations

The Role of Emulsifiers in General 414 Film Formation 415 O/W Sunscreen Formulations 422 Quick-Breaking O/W Sunscreen Emulsions 433 Sprayable O/W Emulsions 437 W/O Emulsions 440 Autoxidation of Emulsifiers 446 References 448 Although the formulation of emulsions is not all that easy, they are the most frequently used vehicle for UV filters. Here, as in all emulsions, the most import- ant structural element is the emulsifier system used; this system is primarily responsible for the stability of the sunscreen emulsion. In addition to ensuring emulsion stability across a broad temperature range, the emulsifier system used contributes to many other quality characteristics of a sunscreen product, for example, easy spreadability on the skin, the waterproofness of the formulation, the film formation during and after application, the stability of the degree of dispersion of micropigments, and product safety-to name only a few examples.