A novel type of caged bicyclic phosphorous functionalized silsesquioxane was synthesized from caged bicyclic phosphorous quadridentate silicon complex in the presence of tetramethylammonium hydroxide. The product was confirmed by FTIR, ²⁹Si MAS NMR, MS and XRD spectra. Thermal analysis tests indicated that as a result of the synergistic effect between phosphorus and silicon, the initial temperature of thermal decomposition of epoxy resin was increased by 45 ℃, and the residual ratio reached to 12.2% at 700 ℃ by adding 5% the synthesized compound.

Key words: phosphorus/silicon synergistic effect, epoxy resin, phosphorous-functionalized silsesquioxane, caged bicyclic phosphorous quadridentate silicon complex