Thermal stability of octadecylsilane hybrid silicas prepared by grafting and sol–gel methods

Hybrid silicas bearing octadecylsilane groups were prepared by grafting and sol–gel (SG) methods. The effect of the preparative route on the thermal stability was evaluated by means of thermal gravimetric analysis (TGA), infrared emission spectroscopy (IRES) and, complementary, by 13C solid-state nuclear magnetic resonance (13C NMR) and matrix assisted laser deionization time of flight mass spectroscopy (MALDI-TOF-MS). Silicas prepared by the grafting route seem to be slightly more stable than those produced by the sol–gel method. This behavior seems to be associated to the preparative route, since grafting affords a liquid-like conformation, while in the case of sol–gel a highly organized crystalline chain conformation was observed.