Interparticle Interactions of Dendrimer, Comb, and Linear Grafted Nanoparticles via Coarse-Grained Molecular Dynamics Simulations.

Rational approaches to impart a robust organic interface on nanoparticle (NP) surfaces for increasing the NP stability and repulsion are critical for advancing nanocomposite-based technologies. However, for applications where the choice of NP cores, binding groups, and ligand chemistry is restricted, the molecular parameter of polymer ligands becomes a crucial design variable. Here, we employ coarse-grained molecular dynamics simulations to examine the effect of ligand architecture, grafting density, and NP size on the dispersion behavior of polymer-grafted NPs. Among the ligand architectures studied (linear, dendron, and comb), comb ligands with short backbones (BBs) and high side chain densities (SCDs) (i.e., number of side chains per BB bead) yield the highest magnitude of repulsion at small interparticle distances followed by the dendrimer ligands and comb ligands with low SCD. Overall, our results underline the importance of precision design for brush ligands to dramatically improve the dispersion behavior and long-term stability of polymer-covered 'hairy' NPs.