Hydroxylated Cyclophosphazene/Silica Hybrid Materials: Synthesis and Characterization

The synthesis of new hybrid materials that are prepared by the sol-gel technique is presented. The synthesis involves the reaction of a free hydroxylic group-containing cyclophosphazene, hexakis(4-hydroxyphenoxy)cyclophosphazene, and a hydrolyzed tetraethoxysilane under acid catalysis. Evidence for the formation of genuine chemical bonds between the hydroxylated cyclophosphazene and the three-dimensional silica network is presented. The formation of these bonds was confirmed by spectroscopic techniques (FTIR, 31P, 29Si, and 13C NMR both in solution and in the solid state and X-Ray Diffraction analysis). The results are supported by thermal characterization of the materials based on Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA) determinations.