ENCAPSULATION OF GOLD NANOCLUSTERS IN SILICA MATERIALS VIA AN INVERSEMICELLE SOL-GEL SYNTHESIS/

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.