Atomistic insights into the effect of polymerization on the thermophysical properties of 2-D C-60 molecular solids

AQ Alsayoud and VR Manga and K Muralidharan and J Vita and S Bringuier and K Runge and P Deymier, CARBON, 133, 267-274 (2018).

DOI: 10.1016/j.carbon.2018.01.044

The ability to polymerize solid-state C-60 molecular crystals via intermolecular covalent bond formation provides controllable routes to obtaining structures with tunable mechanical and thermal properties. In this regard, using molecular dynamics simulations, fundamental insights into the interplay between degree of polymerization and the ensuing evolution in the thermophysical properties of C-60 polymorphs are obtained for the first time. In particular, it is unambiguously shown that 2-D polymerized C-60 polymorphs show a two order of magnitude enhancement in the thermal conductivity and one order of magnitude change in the elastic stiffness. The significant increase in the thermal conductivity is correlated to the presence of new THz thermal phonon modes, characterized by larger mean free paths. In addition, it is also seen that the Debye temperature of the C-60 structures is strongly dependent on the extent of polymerization. The new understanding obtained in this work provides valuable guidelines for the design and development of new C-60 based phononic metamaterials for applications as vibrational and thermal management systems. (C) 2018 Elsevier Ltd. All rights reserved.

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