Aggregation of colloidal particles with a finite interparticle attraction energy

Aggregation of colloidal particles with a finite attraction energy was investigated with computer simulations and with gold particles coated with a surfactant. Computer simulations were carried out with the Shih-Aksay-Kikuchi (SAK) model, which incorporates a finite nearest-neighbor attraction energy-E into the diffusion-limited-cluster-aggregation (DLCA) model. Both the computer simulations and the experiments showed that (i) with a finite interparticle attraction energy, aggregates can still remain fractal, and (ii) the fractal dimension remains unchanged at large interparticle attraction energies and increases when the interparticle attraction energy is smaller than 4 k_BT where T is the temperature and K_B is the Boltzmann constant. The agreement between the simulations and the experimental results suggests that the reversible aggregation process in a colloidal system can be represented by the SAK model.