Poly(allylamine)-stabilized colloidal copper nanoparticles: synthesis, morphology, and their surface-enhanced Raman scattering properties.

Poly(allylamine)-stabilized spherical- and rod-shaped copper nanoparticles are synthesized by a simple chemical reaction. The synthesis is performed by the reduction of copper(II) salt with hydrazine in aqueous solution under atmospheric air in the presence of poly(allylamine) (PAAm) capping agent. Noteworthy of the advantages of the synthetic method includes its production of water dispersible copper nanoparticles at room temperature under no inert atmosphere, making the synthesis more environmentally friendly. The resulting copper nanoparticles are investigated by UV-vis spectroscopy and transmission electron microscopy (TEM). The results demonstrate that the amount of NaOH used is important for the formation of the copper nanoparticles while the reaction time and concentration of PAAm play key roles in controlling the size and shape of the nanoparticles, respectively. The resulting colloidal copper nanoparticles exhibit large surface-enhanced Raman scattering (SERS) signals.