Thermogravimetric analysis of silicas chemically modified with products of deoligomerization of polydimethylsiloxane

Fumed silica has been modified with polydimethylsiloxanes of different polymerization degree (from 4 to 68) in the presence of dimethyl or diethyl carbonate. The samples were characterized by means of IR spectroscopy, elemental analysis, and low-temperature adsorption of argon. Thermal behaviour of grafted organosiloxane layer has been studied using thermogravimetric analysis. Results show that thermal stability of organosiloxane layer depends on the chain length of polydimethylsiloxane used for silica modification and the nature of dialkyl carbonate applied as an initiator for partial deoligomerization of polydimethylsiloxane. Silica modified with mixture of PDMS-100 ( n = 35–68) and diethyl carbonate was found to possess the highest thermal stability among all the samples studied.