Ionic Character and Alkyl Chain Length of Surfactants Affect Titanium Dioxide Dispersion and Its UV-Blocking Efficacy

The dispersion of titanium dioxide (TiO[sub.2]) determines the performance of TiO[sub.2]-based formulations in cosmetic and coating applications. In particular, the chemical and structural characteristics of the surfactants used to prepare TiO[sub.2] dispersions are significant. However, the influence of surfactants on TiO[sub.2] dispersion quality has not been systematically investigated. In this study, we observed the effects of the ionic character of commercial surfactants on the dispersion stability and UV-blocking efficacy of TiO[sub.2]. Among the experimental surfactant groups, anionic sodium dodecyl sulfate was efficient in stabilizing TiO[sub.2] as a water-in-oil formulation and enhancing its UV-blocking efficacy. Furthermore, an anionic fatty acid as a surfactant with a longer alkyl chain length was sufficient to stabilize the TiO[sub.2] formulation, which also displayed the highest UV-blocking efficacy, comparable to the values of commercial TiO[sub.2]-based cosmetic products.