The Effect of Ultrasonic Radiation on Gelation and Properties of Ormosils

Abstract
Ultrasound has been applied to organically modified silicates (ORMOSILs) solutions during gelation. A series of silica and polydimethylsiloxane (PDMS) composites have been prepared by the sol-gel method. Tetraethoxysilane (TEOS), PDMS, water and a HC1 catalyst were mixed and exposed to 20 kHz ultrasonic radiation under different conditions. Ultrasonic radiation made it possible to obtain wet gels in 5 to 30 min. without solvent (e.g. alcohol, and THF). And exothermic reaction was observed due to hydrolysis and polycondensation of TEO S. The reaction process was examined by liquid state 29Si NM R. Densities of obtained sono-ORMOSILs were observed to be higher than those produced by ordinary processes. Some sono-ORMOSIL samples demonstrated extremely low porosity and low specific surface areas.

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