Synthesis of a Polyhedral Oligomeric Silsesquioxane (POSS) containing Phenyl and DOPO (7Ph-T7-DOPO) and its thermal stability

A new type of polyhedral oligomeric silsesquioxane (POSS) (7Ph-T7-Vinyl) containing phenyl and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) was synthesized from phenyltrimethoxysilane, trichlorovinylsilane, and DOPO in high yield. This product was subjected to addition reaction using an AIBN catalyst in toluene. The structure of 7Ph-T7-DOPO was characterized by 1HNMR and FTIR, and 7Ph-T7-DOPO exhibited a crystal structure of (RSi01.5) n. TGA curve analysis showed the high thermal stability of the cage-like compound. The flame-retardant properties of the EP composites were also tested in terms of limiting oxygen index (LOT) and UL-94. Incorporation of 2.5 wt. % DOPO-POSS into epoxy resin (EP-2.5) resulted in an LOT of 27.5 and UL-94 rating of V-1 (t1 = 34 s and t2 = 0 s). All of these results suggested that the 7Ph-T7-DOPO exhibited high thermal stability