Reproducible coarse-grained thermoplastic modeling using flowerMD

Coarse-grained simulations of polymers permit longer lengthscales and timescales to be accessed, but reproducing and extending such simulations can be challenging. These challenges arise from the system-specific and simulation-engine specific details needed to derive or train the coarse force fields, and then apply them. Here we demonstrate the capabilities of the Flexible Library of Organic Workflows and Exstensible Recipes for Molecular Dynamics (flowerMD) for developing and deploying coarse-grained forcefields of thermoplastic polymers. Case studies of poly(ether ketone ketone) and poly(phenylene sulfide) are performed. For each chemistry, we use flowerMD to define all atom molecular dynamics simulations that are used to train a coarse model using multi-state Iterative Boltzmann Inversion, and then we perform large-scale modeling of thermoplastic welds with coarse-grained models of each chemistry. We show how these complete workflows can be specified programmatically with flowerMD python scripts, enabling reproduction and extension. We briefly describe how the structure of PEKK and PPS welds depend on processing conditions and conclude with a discussion of adding new recipes and capabilities.