Universal cohesive law governing interaction between nanoparticles in hairy nanoparticle assemblies

Polymer-grafted nanoparticle assemblies have significant advantages over traditional nanocomposites as they overcome the dispersion issues, attain high structural order and allow accurate tailoring of mechanical properties. Modeling these assemblies using atomistic or even coarse-grained molecular dynamics simulations is quite challenging due to spatiotemporal limitations. To overcome this challenge, in this work, we develop a universal cohesive law that governs the interaction between nanoparticles in these assemblies. This effective interatomic potential is based on the strain energy density between two nanoparticles modeled as plates. We find that the potential consists of empirical constants dependent on polymer fragility, molecular weight and grafting density. Using these design parameters, we were able to collapse all the strain energy curves into a universal curve governing the interaction between nanoparticles. By eliminating the need to explicitly model polymer beads, we can simulate micron scale systems of these hairy nanoparticle assemblies without the loss of underlying physics.