Isolating Chemical Reaction Mechanism as a Variable with Reactive Coarse-Grained Molecular Dynamics: Step-Growth versus Chain-Growth Polymerization

• Main Authors: Karnes, John J, Weisgraber, Todd H, Cook, Caitlyn C, Wang, Daniel N, Crowhurst, Jonathan C, Fox, Christina A, Harris, Bradley S, Oakdale, James S, Faller, Roland, Shusteff, Maxim
• Format: Journal Article
• Language: English
• Published: 04-10-2022
• Subjects: Physics - Chemical Physics; Physics - Materials Science; Physics - Soft Condensed Matter
• DOI: 10.48550/arxiv.2210.01758

We present a general approach to isolate chemical reaction mechanism as an
independently controllable variable across chemically distinct systems. Modern
approaches to reduce the computational expense of molecular dynamics
simulations often group multiple atoms into a single "coarse-grained"
interaction site, which leads to a loss of chemical resolution. In this work we
convert this shortcoming into a feature and use identical coarse-grained models
to represent molecules that share non-reactive characteristics but react by
different mechanisms. As a proof of concept we use this approach to simulate
and investigate distinct, yet similar, trifunctional isocyanurate resin
formulations that polymerize by either chain- or step-growth. Since the
underlying molecular mechanics of these models are identical, all emergent
differences are a function of the reaction mechanism only. We find that the
microscopic morphologies resemble related all-atom simulations and that
simulated mechanical testing reasonably agrees with experiment.