MOLECULAR SIMULATION STUDY OF POLYMER NANOCOMPOSITES WITH HYDROGEN BONDING CHEMISTRIES

Abstract

In this thesis, I present a new coarse-grained (CG) model used to capture directional and specific interactions (eg. hydrogen bonding) present between acceptor—donor sites on graft and matrix chains in polymer nanocomposites (PNCs). This CG model represents acceptor and donor sites partially embedded in graft and matrix monomer beads to create the effect of directionality and specificity needed to mimic hydrogen bonding interactions. Then, this CG model is used in molecular dynamics simulation studies to understand how these directional and specific interactions impact PNC structure. We quantify the structure of the PNC using several methods: the interpenetration of matrix chains into the grafted layer (known as grafted layer wetting) found via concentration profiles, chain conformations described using end to end distance calculations, and the free volume of polymer chains. In collaboration with graduate student Arjita Kulshreshtha and under direction of Professor Arthi Jayaraman, we have found that while equivalent grafted layer wetting can be achieved with directional acceptor-donor interactions and isotropic graft – matrix interactions, there is a distinct difference in local chain structure and free volume in the polymer nanocomposite due to each of these interactions.