Dispersion and Shear Viscosity of a Simulated Polymer Nanocomposite
Francis W. Starr, Jack F. Douglas, S C. Glotzer
Using molecular dynamics simulations, we explore properties affecting nano-filler dispersion in a dense bead-spring polymer melt, and how the state of dispersion alters the response of the system to shear. We determine a simple metric to determine the state of dispersion, which we verify both by visual inspection of the simulated configurations and the structure factor. This measure allows us the determine the behavior of the crossover from clustered to dispersed states, which we show is compatible with a simple model of equilibrium polymerization. Additionally, we find that the effects of temperature and polymer-nanoparticle interactions are largely interchangeable. Hence it might be possible that temperature, rather than complicated functionalization, may be used to control nanoparticle dispersion in some systems. Finally, we show that shear, particularly important under processing conditions, favors dispersion in our systems.