Spherical hybrid silica particles modified by methacrylate groups

Organic–inorganic hybrid materials have been used as fillers to reinforce dental resin composites, which require strengthening to improve their performance in large stress-bearing applications such as crowns and multiple-unit restorations. Homogeneous organic–inorganic hybrid materials with high performance were prepared by mixing 3-methacryloxypropyltrimethoxysilane (MPTS) and tetraethylorthosilicate (TEOS) synthesized by the sol–gel route. The matrix was prepared by hydrolyzing and condensing the TEOS and MPTS, using basic catalysis and excess water. The resulting xerogel was treated at 50, 100, 150, and 200 °C for 4 h, and the structure was analyzed by thermogravimetry (TG/DTA), photoluminescence (PL), nuclear magnetic resonance (NMR ²⁹Si and ¹³C), transmission electron microscopy (TEM), infrared spectroscopy (IR), and Raman spectroscopy. The PL spectra displayed the Eu³⁺ lines characteristic of ⁵D₀ → ⁷F_{J (J = 0, 1, 2, 3, 4)} ions, and the blue emission was ascribed to the silica matrix. TG, MNR and infrared spectroscopy analyses indicated the hybrid silica was stable, with the organic part present up to 150 °C. Increasing the temperature of the heat treatment was found to increase the degree of hydrolysis. The size and morphology of the silica particles were identified by TEM.