Dynamic structure factor scaling in dense gelling silica suspensions

Small-angle neutron scattering data from dense (30% by mass) gelling 7 nm colloidal silica spheres are presented. The coarsening process that occurs during gelation exhibits temporal self-similarity, and the time-dependent structure factor obeys the dynamic scaling relation . Here, q is the scattered wavevector, is the location of the low-angle peak in is a time-independent characteristic structure function which has a maximum at x = 1, and is the fractal dimension. Connections between the silica gelation and spinodal decomposition in a simple fluid are reviewed.