G. Cerveau, Sabrina Chappellet, R. Corriu
Sep 1, 2002
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Journal
Silicon Chemistry
Abstract
A study of the polycondensation reaction of 1,4-bis(trihydroxysilyl)benzene 1H by thermal treatment and by a catalytic route is described. The resulting polysilsesquioxane materials O1.5Si-Ph-SiO1.5have been compared with those obtained by the classical sol-gel route from 1,4-bis(trimethoxysilyl)benzene 1M. From these results it emerges that the solids obtained by thermal treatment of the solid 1H were drastically different from those obtained in solution, either from 1H or 1M. The thermal polycondensation of 1H led to highly polycondensed non-porous solids having a high density. They were organized at the nanometric scale (X-ray) and at the micrometric scale (TEM images). In contrast, the solids obtained by catalytic polycondensation in solution from 1H or by classical sol-gel route from 1M presented similar properties (moderate level of condensation, high specific surface areas). However, they exhibited different TEM images and chemical reactivity. It has been shown that the long range order observed in the case of the thermal treatment of 1H was not the result of an ordinary thermodynamic rearrangement, since the same treatment applied to the solids obtained by polycondensation in solution of 1H and 1M did not allow such organization.