Templating Effect of MoSe2 on Crystallization of Polyethylene: A Molecular Dynamics Simulation Study

In today's world, 2D material-based nanocomposites have become a material system that has an ever-growing technological and scientific importance. Such a hybrid material system synergizes organic molecules and inorganic 2D materials and renders a rich playground for developing functional materials toward diverse applications in electronic, photovoltaics, and nanotribology. The interfaces in the 2D materials/polymer nanocomposites are also considered as the prototypical system to study confinement-induced phase transitions, which requires a comprehensive understanding of the dynamic and static properties on the molecular length and time scales. The fundamental understanding of the interfaces can provide insights into the design of 2D material/polymer nanocomposites with desired properties through interface engineering. However, to date, our understanding about such a heterointerface is still limited due to challenges in experimental testing and theoretical modeling. In this study, polyethylene assembly on 2D MoSe2 has been investigated by conducting molecular dynamics (MD) simulations. An all-atoms model is developed to simulate the guided assembly of n-pentacosane alkane chains, a surrogate model for polyethylene, on the surface of 2D MoSe2. It has been observed that polyethylene molecules crystallize from the interface and the crystallization front moves rapidly toward the bulk. In equilibrium, the assembled polyethylene chains are orientationally registered to the 2D surface under the interplay between the conformational entropy of the polymer chains, the adhesive interface interaction, and the corrugated substrate. This work demonstrates that 2D materials like MoSe2 can be used as a template to create 2D material/polymer nanocomposites with specific bicrystallization orientations for the designed behavior in the resulting nanocomposite.