Synthetic approaches to the preparation of hybrid network materials incorporating carborane clusters

Abstract

A novel type of hybrid organic–inorganic class II materials with carborane-containing units have been prepared from a particular trichlorosilylcarborane-containing precursor. Different polymerisation processes were investigated in order to achieve the formation of materials that incorporate the covalently bonded carborane units and exhibit different structural characteristics. Hydrolytic, and non-hydrolytic sol–gel process were used for the preparation of the hybrid materials with an Si–O–Si-based network, whereas the hybrid material with an Si–NCN–Si-based network was prepared by a carbodiimide sol–gel process. Structural characterisation was performed by solid state NMR, IR, porosimetry and X-ray powder diffraction that reveal the formation of non-porous to porous materials with a high level of polycondensation, a short-range order organisation and the preservation of the covalent bond between the carborane part and the inorganic network. Alternatively, a solid-state process was used and allows the preparation of materials with a higher level of organisation according to polarized light microscopy. The materials are stable to about 450 °C in inert atmosphere, suggesting good thermal stability.