From colloidal aggregation to spinodal decomposition in sticky emulsions

Aggregation mechanisms of emulsions at high initial volume fractions (phi(0 ) >. 0.01) is studied using light scattering. We use emulsion droplets whic h can be made unstable towards aggregation by a temperature quench. For dee p quenches and 0.1 > phi(0) > 0.01, the aggregation mechanism is identified as diffusion-limited cluster aggregation (DLCA). An ordering of the cluste rs, which is reflected by a peak in the scattering intensity, is shown to r esult from the intercluster separation, exhibiting different scaling than t hat observed at lower volume fractions. This manifests an increasing simila rity to spinodal decomposition observed as phi(0) is increased. For bo > 0. 1 and shallow quenches, different mechanisms, closer to spinodal decomposit ion, are observed. These results allow the subtle boundaries between DLCA a nd spinodal decomposition to be explored.