Kinetic study of silicon alkoxides gelation by acoustic and rheology investigations

The study of the sol to gel transition of silicon based materials obtained from alkoxide precursor Si(OCH3)4, catalyzed by a nucleophilic activator (DiMethylAminoPyridin, DMAP) in methanol has been performed by rheological measurements and sound propagation in an audible range. Different samples obtained by varying the initial monomer concentration, the hydrolysis molar ratio or the temperature have been investigated. An increase of any of these parameters leads to a decrease of the gelation time. Furthermore, the variation of the gelation time versus one of these parameters can be described by power or Arrhenius laws. Therefore the gelation time can be deduced for at least any sol–gel material for which the three parameters lie within the investigated range.