A. Martino et al., ENCAPSULATION OF GOLD NANOCLUSTERS IN SILICA MATERIALS VIA AN INVERSEMICELLE SOL-GEL SYNTHESIS/, Chemistry of materials, 9(2), 1997, pp. 423-429
Nanometer-sized gold particles were encapsulated in the micropores of
xerogels and aerogels. The synthesis involves the sequential reduction
of a gold salt followed by sol-gel processing in an inverse micelle s
olution. The inverse micelle solution solubilizes the metal salt and p
rovides a microreactor for the nucleation, growth, and stabilization o
f the nanometer-sized clusters. Hydrolysis and condensation of an adde
d siloxane precursor produces a wet gel embedding the particles. Chara
cterization of the particle size and composition and the particle grow
th process was completed with transmission electron microscopy (TEM),
electron diffraction, and UV-visible absorption spectrometry. Characte
rization of the gel surface areas was completed with N-2 porosimetry.
Material properties determined as a function of the gel precursor (TEO
S vs a prehydrolyzed form of TEOS), the water to gel precursor reactio
n stoichiometry, and surfactant concentration are discussed in terms o
f the unique solution chemistry occurring in the microheterogeneous in
verse micelle solutions.