The fabrication and organization of self-assembled metallic nanoparticles formed in reverse micelles

Metallic iron nanoparticles are synthesized in reverse micelles of cetyltri methyl-ammonium bromide (CTAB) using hydrazine as a reducing agent. Once th e iron nanoparticles have formed inside the micelle, an aqueous solution of HAuCl4 is added to the iron/CTAB mixture. Addition of the aqueous gold sol ution increases the size of the reverse micelle and the Au(III) is reduced to Au(0) via excess hydrazine. Because gold and iron grow with complementar y crystal structures, the metallic gold forms a coating on the outer surfac e of the iron particles. The gold shells on the iron particles provide func tionality and thin films of the gold coated particles have been made by sel f-assembly reactions between the gold surface of the particle and thiol fun ctionalized substrates. (C) 1999 Acta Metallurgica Inc.