Thermal Conductivity of Graphene Wrinkles: A Molecular Dynamics Simulation

Abstract

Based on the nonequilibrium molecular dynamics simulations, the heat conduction in a novel deformation of graphene, named graphene wrinkle (GW), is investigated. Distinct from pristine graphene, the GW exhibits a relatively low thermal conductivity. We observe that the low thermal conductivity stems from the strong phonon localizations, which are concentrated on the joint regions between crests and troughs of wrinkles. The suppression in GW thermal conductivity could be further attributed to the enhanced phonon scatterings, as evidenced by the vibrational density of states (VDOS) attenuation in the low frequency region, the G-band redshift of VDOS due to the flattened phonon dispersion curves (low phonon group velocities), and the decreased phonon lifetime. In addition, we find that the thermal conductivity of GW is almost insensitive to temperature in the range between 200 and 600 K. It is induced by the significant contribution of low frequency phonon modes, which are more influential in the direction perpendicular to the wrinkle texture. This study provides physical insight into the mechanisms of thermal transport in GWs and offers design guidelines for applications of GW related devices.

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Investigation of the properties of nanographene in polymer nanocomposites through molecular simulations: dynamics and anisotropic Brownian motion

“…The conformational and dynamical properties of nanographene in a polymer matrix can be of particular importance. Indeed, both the conformational transitions (rippling or wrinkling) and the mobility of the graphene nanofiller in the composite can strongly affect the properties of the whole material; [26][27][28][29][30] however, there is no obvious correlation between them. For example, it has been observed that both these factors inhibit adsorption of polymer on the surface of a graphene flake in polyethylene/graphene nanocomposites, resulting in a lower density of polymer at the interface, compared to the case of a frozen sheet.…”

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“…The maximum reduction ratios of the thermal conductivity in zigzag GNR and armchair GNR are ∼60% and ∼40% by applying different strains, respectively. Moreover, conducting some specific structures is an effective approach to manipulate the thermal conductivity of the graphene monolayer [14][15][16][17]. Cui et al investigate the k of a novel graphene wrinkle structure using the MD method, which is dropped by 36% and 52% in the parallel and perpendicular directions at 300 K [14].…”