(342as) Theory and Simulation Studies of Structure and Thermodynamics in Polymer Blends and Polymer Nanocomposites with Directional Interactions

Macroscopic properties of polymer blends and polymer nanocomposites (PNCs) depend on their morphology which is governed by the miscibility between constituent polymers in polymer blends or by the dispersed/aggregated state of particles in PNCs. One way to tune morphology is by introducing favorable interactions between components of the blend/nanocomposite; these interactions between the components of the blend/nanocomposite could be either isotropic (i.e., van der Waals) or directional (e.g., hydrogen bonds, pi-pi stacking). Although, directional interactions like hydrogen bonds offer a promising potential route to precisely tune structure within polymeric materials, computational studies on polymers with directional interactions have been limited to atomistic simulations that explicitly represent hydrogen bonding atoms and their interactions making them expensive for simulation of large length and time scale assembly in polymers. Conversely, simulations with coarse-grained (CG) models are able to capture the large length and time scales associated with polymer chains but cannot capture the effects arising due to the specificity and directionality of interactions without using complex anisotropic interaction potentials to model directional interactions. To overcome these challenges in modeling of directional interactions, I will present our development of a CG model that captures the short length and time scales of directional and specific interactions as well as the large length and time scales associated with polymer chains in polymer blends and PNCs. In this poster, I will describe the details of the CG model that allow us to produce effectively anisotropic attractive interactions while still using isotropic interaction potentials. I will then share how we have used the CG model in molecular dynamics (MD) simulations to contrast the local structure and morphology in PNCs with directional interactions to that of PNCs with isotropic interactions. I will also share how using this model in MD simulations, Polymer Reference Interaction Site Model (PRISM) theory, and machine learning (ML) we have quantified the complex phase behavior in immiscible homopolymer blends with dominant hydrogen bonding interactions.