Thermogravimetry, differential thermal analysis, and IR spectroscopy were used to investigate the process of thermal destruction
of adsorbed polydimethylsiloxane (PDMS) in air. The disperse adsorbents were pristine fumed silica and modified fumed silica
whose surface contained oxygen compounds of phosphorus.
It was shown that under the given experimental conditions the thermal destruction of PDMS on the fumed silica surface was
accompanied by the complete transformation of the adsorbed PDMS to SiO2. In the case of phosphorus-containing silica, the thermal destruction proceeded in a different way. It was found that at
140–300C depolymerization of the siloxane chains of a certain part of the adsorbed polymer took place with the concurrent
removal of volatile products of the reaction. However, the remaining part of the adsorbed PDMS interacted with the modified
silica surface to form chemisorbed dimethylsilyl structures. The thermal destruction of the chemisorbed fragments of PDMS
in air was initiated at 400C or above for both types of silica investigated.