Scaling Behaviors of Nanoparticle Clusters That Are Driven through Brush-Decorated Nanopores

Abstract

With the assistance of molecular dynamics simulations, we investigate nanoparticles (NPs) that are driven through a polymer brush-decorated cylindrical channel in a marginally poor solvent. The NPs tend to form clusters due to the repulsive interaction with respect to the polymer brush. Depending on the number of NPs within the channel and the driving force, either individually propagating droplets or a continuous flow state is obtained. We derive approximate scaling relations between the volume of the NP cluster and the number of particles in both states as well as the relation between the number of NPs located on the surface layer of the cluster as a function of the total particle number. These relations are tested by simulations. Furthermore, the conditions under which the dynamic transition between the individual droplet state and the continuous flow state takes place are studied systematically and the corresponding phase diagram is constructed. We also observe a strong hysteresis of this transition with respect to variation of the driving force indicating a barrier between the two stationary nonequilibrium states.