Spinodal-type dynamics in fractal aggregation of colloidal clusters

Abstract

The aggregation of dense colloidal solutions has been investigated by means of low-angle static light scattering. We show that the scattered pattern exhibits a finite-q-vector peak, whose intensity and position ${\mathit{q}}_{\mathit{m}}$ change with time. We find that the intensity distributions scale according to S(q/${\mathit{q}}_{\mathit{m}}$,t)=${\mathit{q}}_{\mathit{m}}$(t${)}^{\mathrm{-}\mathit{d}}$F(q/${\mathit{q}}_{\mathit{m}}$), in agreement with the scaling law for spinodal decomposition. While d=3 for spinodal decomposition, here scaling requires that d=${\mathit{d}}_{\mathit{f}}$, the fractal dimension of the clusters.