A dissipative particle dynamics model for studying dynamic phenomena in colloidal rod suspensions

A dissipative particle dynamics (DPD) model is developed and demonstrated for studying dynamics in colloidal rod suspensions. The solvent is modeled as conventional DPD particles, while individual rods are represented by a rigid linear chain consisting of overlapping solid spheres, which interact with solvent particles through a hard repulsive potential. The boundary condition on the rod surface is controlled using a surface friction between the solid spheres and the solvent particles. In this work, this model is employed to study the diffusion of a single colloid in the DPD solvent and compared with theoretical predictions. Both the translational and rotational diffusion coefficients obtained at a proper surface friction show good agreement with calculations based on the rod size defined by the hard repulsive potential. In addition, the system-size dependence of the diffusion coefficients shows that the Navier-Stokes hydrodynamic interactions are correctly included in this DPD model. Comparing our results with experimental measurements of the diffusion coefficients of gold nanorods, we discuss the ability of the model to correctly describe dynamics in real nanorod suspensions. Our results provide a clear reference point from which the model could be extended to enable the study of colloid dynamics in more complex situations or for other types of particles.

Automated summary

A dissipative particle dynamics (DPD) model is developed to study dynamics in colloidal rod suspensions, where the interaction between solvent particles and rigid linear chains representing individual rods is controlled using a hard repulsive potential. The model accurately predicts diffusion coefficients of single colloids in the DPD solvent, showing good agreement with theoretical calculations based on rod size and including correct Navier-Stokes hydrodynamic interactions. Comparison with experimental measurements of gold nanorod diffusion coefficients validates the model's ability to describe dynamics in real nanorod suspensions and suggests potential for further extension to study colloid dynamics in more complex situations or particle types.