Dissipative Particle Dynamics Simulation of Sonication-Mediated Particle Interactions

Sonication is a powerful dispersion technique that has been used successfully to disperse agglomerates and break partially formed bridges of nano-scaled particles. For micro-scaled particles, recent work in our lab suggests that it may also serve as a viable “thermalization” technique in order to promote close-packed, highly ordered colloidal crystal formation of large (non-Brownian) particles on a surface. In this study, we computationally explore the impact of sonication on particle cluster formation using the Dissipative Particle Dynamics (DPD) technique. DPD is a particle-based (i.e. Lagrangian) simulation technique that captures meso-scopic dynamics of multiphase flows by coarse-graining intermolecular forces. At its most basic, this coarse-graining results in a conservative, dissipative, and random force. Here, the effect of sonication is incorporated into the DPD method as an oscillatory external force with high frequency and low amplitude. By adding the external force from the sonication, we can inspect the microscopic details of the relative importance of the particle interactions as a function of driving parameters (frequency and amplitude) and compare our results to experimental measurements.