Dissipative Particle Dynamics Simulation of Nanoparticle Diffusion in a Crosslinked Polymer Network.

Dissipative particle dynamics simulation is conducted to investigate the diffusion of a nanoparticle in a crosslinked polymer network based on a bead-spring model. Focusing on cases where the particle is comparable in size to the network mesh, we find from rigid networks that the excluded-volume and hydrodynamic interaction effects associated with solvent beads lead to lubricity, which assists the particle to slip through an opening into the adjacent cell. For flexible networks, the hopping mechanism for particle escape becomes less pronounced with higher network flexibility due to either a smaller spring constant or slacker strands, each consisting of more beads. This behavior could be explained by the larger cell size fluctuation and its slower relaxation, whereby large enough openings temporarily formed are longer-lived, increasing the chance for particle hopping.