Understanding Avobenzone Crystallization in Sunscreen Formulations: Role of Metal Oxide-Driven Nucleation and Stabilization Strategies

Abstract

The crystallization behavior of avobenzone in cosmetic formulations has been investigated with a focus on its interaction with titanium dioxide and zinc oxide particles. Characterization studies using SEM, powder X-ray diffraction (PXRD), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDS) reveal that avobenzone undergoes crystallization facilitated by nucleation on the surfaces of these metal oxide grains. The presence of wax and titanium oxide within the crystalline structures further suggests a complex formation, potentially involving catalytic effects on avobenzone nucleation and isomerization. Notably, the addition of ascorbyl palmitate inhibits unwanted crystallization, possibly through competitive complexation with exposed metal ions. These findings underscore the significance of formulation modifications in stabilizing avobenzone against crystallization, ensuring enhanced product stability in cosmetic applications. Future structural studies are anticipated to elucidate the precise nature of these co-crystalline phases, offering insights into optimizing sunscreen formulations for improved performance and longevity.