January Event, January 30th
Featuring Lisa Hall, PhD
Title: Structure-property relationships in polymeric materials from coarse-grained simulations
The synthetic ability to control polymer architecture, such as by grafting chains on nanoparticles at different densities, creating blocky polymer molecules, and including functional chemical groups attached in various ways to the polymer chains, provides a rich parameter space for creating specialty polymeric materials with gradients in local structural and mechanical properties. Coarse-grained molecular dynamics simulations, in which multiple atoms of the original chemical system are grouped into a single spherical bead along a bead-spring chain, are efficient enough to reach the long time and length scales of interest and can provide general guidance to understand structure-property relationships within the large design space. We analyze the molecular behavior in detail and connect polymer conformations to polymer relaxation, ion conductivity, and other dynamic properties. Two examples will be discussed in this talk. First, we consider ion transport within solid polymer electrolytes and show how this depends on how strongly the polymer solvates the ions. Second, we analyze entanglements, constraints in motion imposed on long chains by other chains due to their non-crossability that determine their long time relaxation, in thin films of polymer-grafted nanoparticles. We find that the number of interparticle entanglements per chain is related to mechanical toughness of the material.