Simple method for preparation of cubic Ag nanoparticles and their self-assembled films

Thiol-derivatised cubic Ag nanoparticles were prepared by adding an AgNO3 solution containing a trace amount of alkanethiol into a solution of NaBH4 and sodium oleate. Their preparation and character were compared with randomly shaped Ag nanoparticles. The thiol was used purposely as orientation agent instead of protective agent. Transfer of cubic Ag nanoparticles from aqueous phase into organic phase or to the interface of aqueous/organic phase has resulted in self-assembled films on the surface of microscope slides and of many other substrates. Transmission electron microscope and UV-vis spectra were used to characterize the cubic Ag nanoparticles. The nanoparticle films were also observed using conventional optical and scanning electron microscope. The mechanisms of the nanoparticles phase-transfer and the formation of the self-assembled nanoparticle films are discussed. (C) 2004 Elsevier B.V. All rights reserved.