Molecular Theory of the Structure, Thermodynamics, and Miscibility of Polymer Nanocomposites

Abstract

For systems with finite &phis;, the many body entropic interactions substantially modify the structure of the system. At low epsilonpc, nanoparticle "imprintation" on the polymer matrix occurs, rearranging the particles and destroying much of the fine scale structure seen at &phis; ≈ 0. The sterically stabilized phases become attractive, with long-range, shallow attractive wells. As epsilonpc is increased, polymers binding tighter at particle surfaces, and the structural interactions creep toward the infinite dilution calculations. Novel effects are observed, including volume enhancement (for polymer coated nanoparticle spheres in the repulsive infinite dilution limit) and clustering (for nanoparticles in the bridging infinite dilution limit) structural features. Finally, the thermodynamic bulk modulus of the system is found to universally and monotonically decrease as &phis; is increased.