Adaptability of polyurea microcapsules loaded with octyl salicylate for sunscreen application: influence of shell thickness of microfluidic-calibrated capsules on UV absorption efficiency

Abstract

The common chemical ultraviolet (UV) filters such as octyl salicylate that are used in sunscreen cream may cause irritation and other unknown medical conditions. One possible route to avoid the direct contact of UV filters with human skin is to enclose those filters in microcapsules. In this study, microcapsules with a size calibrated at 78 μm via microfluidics but with different shell thicknesses (0.4 to 2.5 μm) are used for the first time, to study the influence of shell thickness of microcapsules on the UV absorption efficiency. The results show that the shell thickness of microcapsules has no obvious influence on the UV absorption efficiency. Besides, a rough model based on the Beer–Lambert law is used to compare the experimental results.