(524f) Theory and Simulation Studies of Structure and Thermodynamics in Polymer Nanocomposites Containing Grafted Nanoparticles

Polymer nanocomposites (PNCs) are a class of polymeric materials where nanoparticles are added to a polymer matrix to achieve desired macroscopic properties. To achieve the desired macroscopic properties, one needs to control the PNC structure/morphology, i.e. arrangement of nanoparticles within the matrix. It has been shown that by tailoring the polymers that are grafted on the nanoparticles one can tune the effective inter-particle interactions and as a result, the PNC morphology. In this talk, I will share our recent work focused on one specific set of polymer chemistries where hydrogen bonding interactions are present in the graft and matrix chains. Having acceptor-donor (A-D) sites on graft and matrix polymers offers a promising means to obtain a precisely tuned morphology depending on the valency and strength of directional interactions. I will first present a coarse-grained model that we developed to mimic such directional and specific interactions between donor and acceptor sites on monomers along the graft and matrix. Using this model and molecular dynamics (MD) simulations we contrast the effect of isotropic and directional interactions between the graft and matrix chains on the PNC morphology. We characterize the PNC morphology, in particular, the wetting of the grafted layer by the matrix chains, through graft and matrix chain conformations and monomer concentration profiles. In this talk I will present the highlights of our study conducted over a large design space including graft and matrix chain lengths and flexibility, strength of isotropic and directional interaction, grafting density, etc.