Hydrophobic, organically dispersible gold nanoparticles of variable shape produced by the spontaneous reduction of aqueous chloroaurate ions by hexadecylaniline molecules

Abstract

In addition to control over the size and monodispersity of nanoparticle, nanomaterial synthesis procedures are increasingly required to control their shape and assembly as well. We demonstrate in this paper synthesis of organically dispersible, hydrophobic gold nanoparticles of spherical shape and encased in triangular thin polyaniline shells by doing reaction under static conditions and assembly of these particles onto polymer nanorod/nanowire-like templates by varying the molar ratio of chloroaurate ions to hexadecylaniline and varying the solvent by the spontaneous reduction of aqueous chloroaurate ions by hexadecylaniline molecules in a biphasic reaction setup. Under stationary conditions (no stirring), a biphasic mixture of hexadecylaniline in toluene and chloroaurate ions in water leads to the electrostatic complexation of chloroaurate ions with hexadecylaniline at the liquid-liquid interface and their phase transfer into the organic phase, followed by their reduction by the hexadecylaniline molecules. By varying the conditions, the templating action of gold nanoparticles or the polyaniline nanodispersions can be tuned in the organic medium and resulting assembly.