Modeling Pairs of Polymer-Grafted Nanoparticles (PGNs) in Solution

By grafting polymer chains onto nanoparticles (creating PGNs), one can precisely control interparticle interactions. PGNs are typically synthesized and processed in solution before use in applications such as flexible electronics where a precise spacing of inorganic particles in a robust and flexible matrix is desirable. Understanding their solution properties is crucial to control their structure during deposition and drying. We use coarse-grained molecular dynamics (MD) simulations to study the chain conformations and effective interactions between two PGNs in implicit solvent. Specifically, we use a Kremer-Grest type of model for graft chains and spherical nanoparticles ten times the monomer size. Nanoparticle interactions are of an integrated form as though they are composed of a uniform melt density of monomers. Monomers interact via mixed Lennard-Jones potentials; the repulsive part is kept constant while an attractive part is added with adjustable strength to consider various solvent strengths. As expected, in good solvent, we find that higher graft density yields more extended chains and a larger effective repulsion between PGNs. At lower solvent strength, PGN-PGN interactions become attractive; details of chain conformations and effect of graft density will be discussed.