Slow salt-induced aggregation of citrate-covered silver particles in aqueous solutions of cellulose derivatives

In this work, the salt-induced aggregation of bare and polymer-covered silver particles has been studied with the aid of light scattering and UV-visible spectroscopy. Light scattering on a suspension of bare silver particles at a low salt concentration shows that the cluster fractal dimension d (f) changes from 1.6 to 2 in the course of the aggregation process, whereas no restructuring of the clusters is observed at a higher salinity where d (f) a parts per thousand aEuro parts per thousand 1.6. The growth of the clusters over time can be described by a power law R (h) aeaEuro parts per thousand t (alpha) , where R (h) is the apparent hydrodynamic radius. The UV-visible experiments revealed that increasing the size of the bare silver particles lead to a significant broadening and red-shift of the absorbance band, whereas for salt-induced growth of Ag clusters, a blue-shift and broadening was observed. Addition of salt to a suspension of silver particles and hydroxyethylcellulose divulged a slower broadening of the surface plasmon peak than without polymer.