Drawing on past experience with carbon nanostructures, including fullerenes and nanotubes, computer modeling will be used to study the interaction between nanoparticles and polymers. Ab initio Density Functional calculations will identify optimum bonding sites of specific functional groups, and characterize the bonds in terms of electronic structure as well as stability. In close collaboration with the experiment, predictive calculations will be used to explore ways to chemically modify the bonding sites and cross-linking geometries, to design polymer-based composites with particular mechanical properties.