Semiconductor and Metal Nanoparticle Formation on Polymer Spheres Coated with Weak Polyelectrolyte Multilayers

We report the in situ formation of semiconductor and metal nanoparticles (NPs) on colloid particles precoated with weak polyelectrolyte multilayers. Poly (acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) multilayers were assembled on the colloid spheres by the layer-by-layer technique and by exploiting copper ions as templating entities, as demonstrated by us earlier (Adv. Funct. Mater. 2003, 13, 929). Metal sulfide and metallic nanoparticles (NPs) were formed within PAH/PAA multilayers assembled on the polymer spheres by the adsorption of metal ions onto uncompensated functional groups of the polyelectrolytes (carboxylate or ammonium moieties), followed by reaction with hydrogen sulfide or sodium borohydride. Coating architectures comprising single or multi-shell NP layers were prepared, depending on the combination and sequence of weak and strong polyelectrolytes used for confining nanoparticle formation. The presence of the NPs within the polyelectrolyte matrixes was confirmed by UV-vis spectroscopy, energy-dispersive X-ray analysis, and transmission electron microscopy. We demonstrate that the method used permits the formation of organicinorganic heterostructures incorporating a diverse range of NPs, ranging from sulfides such as PbS to metals such as gold.