466108 Using Molecular Simulation to Develop a Physically-Based Materials Genome for Semicrystalline Polymer Nucleating Agents

Monday, November 14, 2016: 5:00 PM
Continental 1 (Hilton San Francisco Union Square)
Alexander Bourque and Gregory C. Rutledge, Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA

Molecular dynamics simulations were performed to assess the effect of various additives on the nucleation and growth of an oligoethylene. Heterogeneous nucleation was studied for a broad range of substrates by systematically adjusting the parameters that defined the additive material. A suite of techniques developed to study nucleation and growth in oligoethylene by molecular simulation was used to quantify the impact of different substrates on the resulting crystallization behavior. The time lag to steady-state crystal growth was identified as a key metric for evaluating nucleating efficiency. Increasing the surface attractive forces benefited nucleation, however with diminishing returns. A scan of the substrate lattice parameters revealed significant reduction in time lag when the substrate and polymer crystal unit cells were in crystallographic registry, suggesting an epitaxial mechanism. Substrate rigidity also influenced crystal phase nucleation, but its effect was tied to lattice matching between the substrate and polymer crystal. In this work we present a physically-based materials genome, to which molecular simulation is applied systematically to optimize the nucleating agent activity for a particular family of additives.

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