Organocyclophosphazenes Silica Hybrid Materials I. Synthesis and characterization of siloxane monomers and of cyclophosphazene SiO2 composites

In the context of developing new phosphazene/silica hybrids for preparation of thermally resistant membranes for gas separation processes, two cyclophosphazenes/organosiloxane monomers (1 and 2, scheme I) were synthesized via aminolysis of hexachlorocyclotriphosphazene Cl) with the monoamine functional trialkoxysilanes: 3-(triethoxysilyl)-propylamine (H2N-(CH2)(3)-Si(OC2H5)(3)) or 3-(trimethoxysilyl)-propylamine (H2N-(CH3)(3)-Si(OCH3)(3)), respectively, as new starting compounds for cyclophosphazene/SiO2 composites prepared by the sol-gel process. The siloxane monomers, N3P3Cl3[N(CH2)(3)Si(OCH3)(3)I-3 (1) and N3P3Cl4[N(CH2)(3)Si(OCH2CH3)(3)I-2 (2), as well as the corresponding composites {N3P3Cl3[N(CH2)(3)I-3}(y)- (SiO2)(41y) (1') and {N3P3Cl4[N(CH2)(3)I-3}(y)-(SiO2)(80y) (2') issues from the sol-gel process, have been characterized by infrared spectroscopy and elemental analysis, TG-DTA-DSC coupled thermal analyses, as well as by XPS, XRD, and SEM-EDAX investigations.