Effect of nanorod physical roughness on the aggregation and percolation of nanorods in polymer nanocomposites

Polymer nanocomposites (PNCs) with nanorods as fillers are useful in energy storage, soft electronics, and photonics applications, with the PNC functionality depending strongly on the nanorods' structure within the PNCs (i.e., dispersion, aggregation, orientational alignment, percolation). Nanorods' structure in PNCs can be controlled by nanorod size (diameter, aspect ratio), chemistry, and surface functionalization. Even though many simulation studies have focused on the morphology and dynamics of nanorods in polymer melt using coarse-grained models of nanorods, studies have not demonstrated how the nanorod roughness impacts the phase behavior of nanorods in the polymer melt. In this talk, using molecular dynamics simulations, we elucidate the effect of nanorod roughness on nanorod aggregation, dispersion, and percolation in polymer nanocomposites. By choosing coarse-grained models that enable systematic variation of the nanorod roughness and by selecting purely repulsive pair-wise interactions for nanorods and polymer chains, we show how nanorod roughness affects the entropic driving forces for various PNC morphologies. Our study serves as design rules for achieving desired morphologies in PNCs with synthetic and biologically derived nanorods and nanowires that have varying extents of physical roughness.