Understanding the Dispersion and Aggregation of fillers in Polymer Nanocomposites using Dissipative Particle Dynamics (DPD) Simulations of Polymer-Filler Blends*

Enhancing the properties of polymeric systems such as natural rubber by the addition of suitable additives provides for interesting applications, both mundane and novel. Such nanocomposites contain nanoscale fillers of varying miscibility, including carbon black, silica, metal oxides, pigments, and/or various combinations thereof. These complex systems exhibit rich phase behavior resulting from thermodynamic interactions and kinetic history. In this research, we perform Dissipative Particle Dynamics (DPD) simulation of polymer chains with aggregated and free filler particles, varying polymer-polymer, filler-filler, and polymer-filler interaction energy, to understand the hierarchical structure and dispersion over multiple length and time-scales. Our results demonstrate the role of concentration, temperature and interaction strength on the clustering of fillers, investigated via their fractal dimension, the radius of gyration, mesh size and population distributions, and are compared with small-angle x-ray scattering data.