Manipulating core-shell reactivities for processing nanoparticle sizes andshapes

This paper describes new findings of an investigation of thermally-activate d core-shell reactivities of nanoparticles in solutions for processing size , shape and surface properties. Gold nanoparticles of approximate to 2 nm c ore sizes with thiolate monolayer encapsulation were chosen as a model syst em for the manipulation of reaction parameters, including annealing effect, core composition and shell structure. It is revealed that, upon an evoluti on of particle sizes, annealing treatment of the solution in the presence o f encapsulating thiols can lead to the formation of highly monodispersed na noparticles. New insights into shell desorption, core coalescence and shell re-encapsulation have been provided by dependencies of the evolution tempe rature on the capping thiolate chain length and the core alloy composition. Transmission electron microscopic, FTIR and UV-Visible techniques were use d to characterize the morphological and chemical properties. The implicatio n of the results for the development of abilities in chemical processing co re-shell nanoparticles is discussed.