Polyphosphazene-metal oxide hybrids by nonhydrolytic sol-gel processes

Three ways have been studied for the preparation of phosphazene-metal oxide hybrids in which the phosphazene units were covalently linked to the metal through P-O-M bonds,condensation between hexachlorocyclotriphosphazene and metal alk oxides (Si, Ti), between hexaalkoxycyclotriphosphazene and metal chloride, and between the two chlorides in the presence of ether. Nonhydro lytic condensation between tetrachlorosilane or titanium chloride and hexaa lkoxycyclotriphosphazene is the best way for the preparation of covalently linked cyclotriphosphazene-metal oxide hybrids. The composition of the hybr ids can be controlled by using a mixture of alkoxyphosphazene, metal chlori de and metal alkoxide when the metal is titanium or aluminium. This mode of condensation has been applied to polyphosphazene.