Synthesis of acrylic-modified sol–gel silica

Silica was obtained by sol–gel process through hydrolysis and condensation of tetraethyl orthosilicate (TEOS) using molar fraction of H₂O/TEOS=9 under alkaline catalysis, at different reaction times (5 min to 24 h). At the end of each time, the reaction medium appeared as a suspended microparticle system. After solvent evaporation, the yield was calculated to be around 100% and practically independent of the time of reaction. The silica had its surface modified through the condensation reaction with acryloyl chloride forming organically modified silica. The unmodified and modified silica were characterized by thermogravimetry and derivative thermogravimetry (TG/DTG), infrared spectrometry (FT-IR), size particle and optical microscopy (OM). The acrylic content was independent of the reaction time. The methodology represents an alternative route to obtain silica with an unsaturated organic group, able to polymerize and stabilize up to 300–400°C. The modified material has a potential application as compatibilizing filler in dental composite.