A simple and universal strategy for construction and application of silica-based flame-retardant nanostructure

Inorganic-organic nanocomposites present excellent comprehensive performance due to the combination of the advantages of inorganic, organic, and nanotechnology. However, the preparation methods are usually complex and inefficient, especially not universal. Here, a simple and universal strategy was designed for preparing silica-based nanocomposite flame retardants. Mesoporous silica (m-SiO2) was used to load ethylenediamine tetra(methylene phosphonic acid) (EDTMPA). Above the melting point of EDTMPA, molten EDTMPA enters into the mesoporous channels of m-SiO2 by means of capillary force. After cooling, EDTMPA is fixed in the mesoporous cavity to form a flame retardant nanostructure containing silicon, phosphorus, and nitrogen (SiP). The whole process of mesoporous silica-loaded organic flame retardant is simple and green. Adding 3 phr SiP2 into epoxy (EP) resin can reduce the peak heat release rate, total smoke production, and peak CO production by 44.3%, 30.4%, and 45.5%, respectively. Besides, it shows good mechanical properties compared with the EP composites with physically blended m-SiO2 and EDTMPA. These excellent performances are attributed to the combined effect of EDTMPA and m-SiO2 as well as the nanoscale effect. This strategy provides a simple, efficient, and general method to prepare nanocomposites by loading molten organic compounds into m-SiO2.