Synthesis of aluminum phosphate–coated silica: effect on mechanical properties and flame retardancy of epoxy resin

Abstract

The designability of the morphology and composition of inorganic particles plays a vital role in controlling the flame retardancy of polymers, an arena in which inorganic fillers have become a hot spot in the research field of halogen-free flame retardants. Here, aluminum phosphate (AlPO4)-coated silica (SiO2) (SiO2@AlPO4) particles were prepared via a facile one-pot heterogeneous precipitation strategy. The effect of the AlPO4 content on the morphology of SiO2@AlPO4 was systematically studied to regulate the dispersion of AlPO4 nanoparticles. Moreover, the effect of SiO2@AlPO4 on the flame retardancy of epoxy (EP) resin was further investigated. Results show that SiO2@AlPO4 simultaneously strengthens the mechanical properties and improves the flame retardancy of EP and that this phenomenon may be attributed to the synergistic effect of the AlPO4 nanoparticles and SiO2 microparticles. This work details a facile yet effective strategy to engineer the morphology and composition of inorganic particles to control the properties of polymers.