a manufacturing method of ladder - like phosphorus - containing polysilsesquioxanes nanocomposite material is disclosed . the method uses a reaction between ladder - like phosphorus - containing polysilsesquioxanes and modified epoxy . besides improved char yield and limiting oxygen index , thermal degradation rate of the nanocomposite material is lowered dramatically so that the nanocomposite material possesses excellent flame retardance and thermal stability . moreover , optical transparency of the nanocomposite material according to the present invention is still good , not being reduced by increased amount of polysilsesquioxanes . thus the nanocomposite material is applied to decorative paints or protective paints .