(712d) Invited Talk: Equilibrium Structure and Thermodynamics of Polymer Nanocomposites

Koski, J., University of Pennsylvania
Chao, H., University of Pennsylvania
Lindsay, B., University of Pennsylvania
Riggleman, R. A., University of Pennsylvania

In applications involving polymer nanocomposites, controlling the dispersion of the nanoparticles is one of the most critical aspects of their design. For example, optimal mechanical properties are typically found when particles are maximally dispersed, while varying the interparticle spacing on the nm length scale can tune the optical properties of a composite. In all of these cases, the distribution of nanoparticles is a complex interplay of entropic and energetic interactions between the matrix polymers, nanoparticles, and any surface-grafted polymers on the particles. Recently, my group has been extending the polymer field theory framework to study the properties of polymer nanocomposites where the polymer matrix is either a phase separated polymer blend or a block copolymer. This framework has the advantage of being computationally efficient and easily able to deal with inhomogeneous (phase-separated) systems. In this talk, I will briefly describe the general features of our computational framework and our approach for validating the method. I will then spend most of my time describing our work studying the distribution of spherical and rod-like nanoparticles in block copolymer thin films, where our results agree very well with recent experiments. Finally, I will show some of our results looking at the thermodynamics of grafted nanoparticles in various polymer matrices. In this system, we find that the thermodynamics of the grafted particles depends very sensitively on the relative size of the particle core to the grafted chains.