Preparation of Core-Shell ZrO2@SiO2 Nanoparticles and Its Effect on Properties of Composites

In this study, ZrO2@SiO2 nanoparticles with core-shell structure were prepared by Stober method using tetraethyl orthosilicate (TEOS) as the silicon source. The core-shell structure of nanoparticles was characterized via transmission electron microscopy (TEM). The results showed that the surface of ZrO2 could be uniformly coated with SiO2 and the thickness of the SiO2 shell was about 10 nm. The prepared ZrO2@SiO2 nanoparticles were modified with 3-methacryloxypropyltrimethoxysilane (gamma-MPS) and the graft ratios were analyzed by FTIR and TGA. After modified with SiO2 shell, the graft ratio of gamma-MPS on ZrO2@SiO2 nanoparticles increased to 4.03%. Then the modified ZrO2@SiO2 nanoparticles were added into the quartz fibers (QFs) reinforced composites to prepare fiber posts with radiopacity. The effects of the nanoparticles on the mechanical properties of fiber posts were investigated by universal testing machine. The flexural strength of the composite material is reduced with the addition of ZrO2. While with the modified ZrO2@SiO2 nanoparticles, the flexural strength can be improved even if the content of the inorganic nanoparticles is relatively high.