Directing oleate stabilized nanosized silver colloids into organic phases

Nanosized hydrophobic, oleate stabilized silver organosols in various organic solvents are obtained using a solvent exchange method. The silver particles are initially prepared as a hydrosol in the presence of sodium oleate (surfactant). Then a transfer of the colloid to an organic phase is induced by a low concentration of several agents such as orthophosphoric acid, with a transfer efficiency of 50-70%. The hydrophobic colloid is stable and the particles retain their integrity even after the solvent is evaporated and the dried deposit is resuspended in a variety of other solvents. We present the preparation method in detail and characterize the hydrosol and organosol particles by electron microscopy, electrophoresis, and UV-visible extinction spectroscopy. On the basis of IR spectroscopy we discuss the conformation of the surfactant adsorbed on the silver cores and the changes in it as the particles transfer into the organic environment.