Preparation and ultraviolet sunscreen properties of organic-silica hybrid particles encapsulated benzophenone-3

In the present study, ultraviolet (UV) absorptive organic-silica hybrid particles with naturally UV absorption, 2-hydroxy-N-[3-(triethoxysilyl)propyl]benzamide (2-HTESC), have been synthesized through the reaction of 3-aminopropyltriethoxysilane (APTES) and salicylic acid. The chemical structure of 2-HTESC monomer was characterized by FT-IR and 1H NMR spectra. Since benzophenone-3(BP-3) was often served as an organic UV filter in sunscreen formulations, yet its allowable load was limited to 6% in the formulations of lotions and creams. Therefore, our goal was to prepare an absorber (2-HTESC) with its own UV absorption to trap BP-3 to construct a target sunscreen BP-3@P2-HTESC composite material with dual sun protection functions, while also reducing the leakage of BP-3 into emulsion and cream. By comparing the two reactions, it was found that the self-catalytic reaction was superior to the alkali-catalyzed reaction. BP-3 was successfully loaded into P2-HTESC molecular network by hydrolytic polycondensation under self-catalytic condition, and the maximum encapsulation rate reached 68%. In addition, BP-3@P2-HTESC-1 sunscreen under self-catalytic reaction showed good UV absorption, excellent thermoresistance, and less controlled release of BP-3 organic molecules to match the maximum allowable amount of BP-3 in sunscreen products. Graphical abstract