Etude et modélisation de la précipitation de la silice selon le procédé Stöber en phase homogène et en émulsion

Abstract : The study of the precipitation of amorphous silica starting from Tetraethoxysilane (TEOS) and water according to the Stöber process, made it possible to quantify the kinetics of the reaction by Fourier-Transform Infrared spectroscopy. We demonstrated that the particles grow by aggregation of the nuclei, which are formed throughout the reaction.The transposition of this process in water-in-oil microemulsion made it possible to synthesize silica nanoparticules with controlled sizes. The hydrolysis of the TEOS is here ten times weaker than in homogeneous phase. When we add the TEOS to the microemulsion, we observe a coalescence of the droplets accompanied by inter-micellar exchanges. This coalescence is well described by a core of aggregation which depends on the concentrations of the surfactant and the non-hydrolysed TEOS. The study of this process in macroemulsions showed the destabilizing effect of ethanol and the need for stabilizing the emulsion to synthesize spherical particles
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Nadia Gabsi-Wolf. Etude et modélisation de la précipitation de la silice selon le procédé Stöber en phase homogène et en émulsion. Autre. Institut National Polytechnique de Lorraine, 2007. Français. ⟨NNT : 2007INPL041N⟩. ⟨tel-01752819⟩

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