Dissipative Particle Dynamics (DPD) Simulation to understand the impact of Filler Morphology on Dispersion and Aggregation in Polymer Nanocomposites

Nanoscale fillers are widely used in polymeric systems such as natural rubber as inexpensive and effective additives for improved properties and functionality. The behavior of such fillers as well as their impact on nanocomposite efficacy, is influenced by hierarchical filler structure, the interaction between fillers-polymer matrix, and processing history. The extensive thermodynamics and kinetic histories of such systems typically result in a complex partitioning of the components and affect the polymer-filler dispersion. In this research, we perform Dissipative Particle Dynamics (DPD) simulation of polymer-irregular filler blends, to understand the hierarchical structure and dispersion over multiple lengths and timescales, while varying polymer-polymer interaction energy. In particular, we highlight the influence of filler aggregate parameters (size, fractal dimension, sticking probability) on morphology. Our results demonstrate the complex role of filler primary and aggregate structures and concentration on nanocomposite physical properties such as particle clustering, percolation threshold, and mesh size. We also explore pathways for the formation of large percolating aggregates, as a function of polymer-filler interaction, validated against small-angle x-ray scattering.