The soluble species present in the reaction mixture that leads to silica nanoparticle production through the base
catalyzed hydrolysis of tetraethyl orthosilicate (TEOS) and the successive condensation were investigated in situ,
under the actual synthesis conditions, by means of 1H, 13C, and 29Si NMR spectroscopy. The two former nuclei, owing
to higher sensitivity and their presence both in the reacting species and in the constituents of the W/O microemulsion
(cyclohexane-igepal-CA-520-concentrated ammonia solution) afforded insight into the inverse microemulsion and
allowed us to assess the kinetic rate of the hydrolysis step. It was verified that the microemulsion microstructure is
maintained during the reaction. The characterization of the final nanoparticles was carried out by means of transmission
electron microscopy (TEM). Special attention was paid to the reaction medium, and an extended assignment of the
1H and 13C resonances of the surfactant headgroup is reported together with the discussion of the changes they undergo
due to the environmental modifications induced by transition from cyclohexane solution to W/O microemulsion and
further toNH3 containingW/Omicroemulsion. The self-diffusion coefficient measurements revealed thatNH3 exchanges
among the inverse micelles diffusing through cyclohexane and confirmed that the preferred localization for ethanol,
a byproduct of the reaction, is the bulk oil.
