Molecular dynamics simulation of polymer-nanoparticle composites: Nanoparticle interactions in a neat polymer matrix.

We have performed molecular dynamics (MD) simulations of model polymer-nanoparticle composites consisting of spherical particles and bead-spring polymer chains. The matrix-induced effective interaction (potential of mean force) between nanoparticles has been determined as a function of polymer molecular weight and strength of the polymer-nanoparticle interaction. We discuss the relative importance of the entropic and enthalpic contributions to the potential of mean force as well as nanoparticle aggregation behavior investigated using implicit polymer model simulations where nanoparticle-nanoparticle interactions are described by the potential of mean force obtained from the explicit matrix simulations.