Molecular Dynamics Simulation of Surface Nucleation during Growth of an Alkane Crystal
Author(s)Bourque, Alexander Jules; Rutledge, Gregory C
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Crystal growth from the melt of n-pentacontane (C50) was studied by molecular dynamics simulation. Quenching below the melting temperature gives rise to propagation of the crystal growth front into the C50 melt from a crystalline polyethylene surface. By tracking the location of the crystal–melt interface, crystal growth rates between 0.02 and 0.05 m/s were observed, for quench depths of 10–70 K below the melting point. These growth rates compare favorably with those from a previous study by Waheed et al. [ Polymer 2005, 46, 8689−8702]. Next, surface nucleation was identified with the formation of two-dimensional clusters of crystalline sites within layers parallel to the propagating growth front. Critical nucleus sizes, waiting times, and rates for surface nucleation were estimated by a mean first passage time analysis. A surface nucleation rate of ∼0.05 nm⁻² ns⁻¹ was observed, and it was nearly temperature-independent. Postcritical “spreading” of the surface nuclei to form a completely crystallized layer slowed with deeper supercooling.
DepartmentMassachusetts Institute of Technology. Department of Chemical Engineering
American Chemical Society (ACS)
Bourque, Alexander et al. “Molecular Dynamics Simulation of Surface Nucleation During Growth of an Alkane Crystal.” Macromolecules 49, 9 (May 2016): 3619–3629 © 2016 American Chemical Society
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