Synthesis of monodispersed ZnO@SiO2 nanoparticles for anti-UV aging application in highly transparent polymer-based nanocomposites

Transparent ZnO/polymer nanocomposites with good UV shielding performance have shown great potential applications. Due to the photocatalytic activity of ZnO, core–shell structure nanoparticles (NPs) have been used to fabricate the transparent polymer-based nanocomposites. However, it is still a challenge to synthesize core–shell structure NPs with small particle size and good dispersity, and difficult to maintain the transparency of the nanocomposites because of Rayleigh scattering caused by the big size or the aggregation of NPs. This article reports a novel reverse microemulsion combined with surface modification method for the synthesis of monodispersed silica-coated ZnO (ZnO@SiO2) NPs, which are introduced into ethocel (EC) matrix to fabricate the transparent nanocomposites by the solution-mixing method. The ZnO@SiO2 NPs with an average size of 12 nm have an obvious core–shell structure and show excellent monodispersity in toluene. The as-prepared EC/ZnO@SiO2 nanocomposites shield all the UV light completely under 350 nm and maintain the transparency of pure EC even the solid content reaches 60 parts per hundred of EC resin by weight (phr). Importantly, the photocatalytic activity of ZnO NPs is eliminated thoroughly by the silica shell, which apparently improves the UV aging resistance of polymer (EC), enabling the applications of ZnO as durable and environmental friendly UV blocker in transparent plastics and coatings to extend the lifetime of the products.