Stable silver colloidal dispersions using short chain polyethylene glycol

Herein we report a 'one pot' facile method for environmentally benign production of stable Ag colloids, using short chain polyethylene glycol as solvent, reducing agent and stabilizer. Stable spherical metal particles 15-30 nm in diameter with a well-crystallized structure were obtained at 30 degrees C. Heating to 60 degrees C resulted in increased spherical sizes, and heating over 90 degrees C led to a mixture of shapes: smaller spherical crystallites and bigger triangular and pentagonal nano-sized prisms. The stability of the Ag colloids submitted to normal chemical laboratory light over a 6-month period was monitored by UV-vis and electron microscopy. The colloids prepared at 30 and 60 degrees C were stable, while in the colloids obtained at 120 degrees C we observed significant particle growth and aggregation of nanoparticle assemblies sized up to several micrometers. (c) 2007 Elsevier B.V. All rights reserved.