The hydrolysis-polycondensation of organically modified Si-alkoxides leads to the obtaining of inorganic-organic hybrid materials
in which the organic moieties remain as permanent groups bonded to the inorganic network.
The molecular species previously determinated by GC-MS during the gelation process have been significantly different according
to the type of the alkoxide used.
In the present work, thermal stability of SiO2-based inorganic-organic hybrid materials starting with TEOS (tetraethoxysilan), MTEOS (triethoxymethylsilan), VTEOS (triethoxyvinylsilan)
and MTMOS (trimethoxymethylsilan) was studied.
The molecular structure of the gels obtained determines differences in their thermal behaviour. Gels obtained starting with
MTEOS show the highest thermal stability, while gels obtained using VTEOS the lowest, among the substituted alkoxides. A particular
behaviour presents the gel obtained with MTMOS that decomposes in four steps. This could be explained by the presence in the
gel of some prevalent types of molecular species with different thermal stability.