Aggregation kinetics of polymer colloids in reaction limited regime: experiments and simulations

The kinetics of reaction-limited cluster aggregation of fluorinated polymer colloids in a broad range of particle volume fractions has been investigated experimentally by measuring independently the Fuchs stability ratio W and the time evolution of both the average radius of gyration 〈Rg〉 and the average hydrodynamic radius 〈Rh〉 of the aggregates mass distribution. The W value is determined from the aggregation rate at the very initial stage of the aggregation, where the presence of triplets is negligible. The time evolutions of 〈Rg〉 and 〈Rh〉 are then simulated using the cluster mass distribution calculated from the population balance equations with various aggregation kernels proposed in the literature. It is found that, when the measured W value is used, the only kernels that can correctly simulate the experimental results are the product kernel and the one derived by Odriozola et al. (Europhys. Lett. 53 (2001) 797), with some proper tuning of the exponent in the kernel. For the particle volume fraction φ<1%, the obtained value for the exponent is 0.4 and independent of φ, while it tends to decrease for larger φ values, most likely indicating a significant effect of multi-body interactions on the aggregation kinetics.