MINERALIZATION OF GOLD NANOPARTICLES IN A BLOCK-COPOLYMER MICROEMULSION

Controlled mineralization of gold nanoparticles has been performed in a microemulsion of polystyrene-block-poly(2-vinylpyridine). The starti ng point was the formation of a thermodynamically stable dispersion of HAuCl4 in inverse micelles of the block copolymer in toluene, which b ecame metastable when the fold was reduced. Kinetic control of the tra nsformation allowed the following stages of the mineralization/coagula tion process to be stabilized: 1) one gold particle per micelle, 2) ag gregated micelles containing two or three gold particles, and 3) a sta te in which empty micelles coexist with larger polymer-stabilized gold particles. Distinctive variations in the spectra were observed depend ing on the particle size and whether two particles had formed a couple with orientation-dependent dipolar interactions.