Molecular modeling and simulation of polymer nanocomposites at multiple length scales

The complexity of intermolecular interactions and confinement in polymer - nanoparticle systems leads to spatial variations in structure and dynamics at both the meso- and nanoscale. Molecular simulation holds great promise as a means of predicting these effects and understanding their microscopic origin. In order to shed some light onto local structure and segmental dynamics of PS/SiO₂ silica and PS/C₆₀ fullerene melt systems, molecular simulations have been conducted using two interconnected levels of representation: (a) A coarse-grained representation. Equilibration of coarse-grained polymer-nanoparticle systems at all length scales is achieved via connectivity-altering Monte Carlo (MC) simulations. (b) An atomistic representation. Initial configurations for atomistic Molecular Dynamics (MD) simulations are obtained by reverse mapping well-equilibrated coarse-grained configurations. The local structure around a silica nanoparticle immersed in polystyrene matrix, PS segmental and local dynamics in both composites and mechanical properties and entanglements in PS/SiO₂ are studied.