New functionalized cyclotriphosphazenes - synthesis and application in the sol-gel process

Abstract

New cyclotriphosphazene (CP) derivatives bearing two or six triethoxysilyl groups were synthesized via aminolysis of N3P3Cl6. With a view to decreasing the steric hindrance in the consequent sol-gel process, silane groups in a non-geminal position were introduced in the phosphazene ring in a two-step reaction. In the first stage, non-geminal tetrasubstitution with morpholine or dimethylamine was performed. In the second stage, the preserved non-geminal chlorine atoms were replaced by 3-aminopropyl-triethoxysilyl groups. The structures of the products were confirmed by IR, 1H-NMR, 13C-NMR, and 31P-NMR spectroscopy. The reactivity of the triethoxysilyl-containing CPs in the formation of a SiO2 network was proved in the presence or in the absence of tetraethoxysilane (TEOS). By adding a water-soluble polymer — poly(vinyl alcohol) — as a third component, organic-inorganic composites were prepared and characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).