NONFRACTAL COLLOIDAL AGGREGATION

We have investigated the growth kinetics and aggregate structure for temperature-induced aggregation of silica colloids in a binary mixture of 2,6-lutidine and water. Using static light scattering, we find that the structure factor obeys Porod's law, the average cluster mass M(t)BAR is similar to t, and the average cluster radius R(t)BAR is similar to t1/3. This indicates that the clusters are compact, MBAR is similar to R3BAR, and that the rate of aggregation is diffusion limited. Such a dense structure suggests that the bonds between the colloids are not rigid, in contrast to what is currently found for colloidal aggregation of solid particles.