Manipulating the Thermal Conductivity of the Graphene/Poly(vinyl alcohol) Composite via Surface Functionalization: A Multiscale Simulation

SD Yang and WF Zhang and RB Ma and HX Li and YL Lu and XY Zhao and LQ Zhang and YY Gao, LANGMUIR, 39, 9703-9714 (2023).

DOI: 10.1021/acs.langmuir.3c00677

The reverse non-equilibrium moleculardynamics simulation is usedto investigate the influence of functional groups (FGs) on the thermalconductivity of a graphene/poly(vinyl alcohol) (PVA) composite, whichconsiders non-polar (methyl) and polar (hydroxyl, amino, and carboxyl)groups. First, the polar groups can be more effective to improve theinterfacial thermal conductivity than the non-polar group. This canbe explained well by characterizing the interfacial Coulombic energy,number and lifetime of hydrogen bonds, vibrational density of states,and integrated autocorrelation of the interfacial heat power. Moreover,the hydroxyl group can improve the interfacial thermal conductivitymore than the other groups, which can be rationalized by analyzingthe surface roughness of graphene and the radial distribution functionof FGs and the PVA chains. However, the introduction of FGs destroysthe graphene structure, which consequently reduces the intrinsic thermalconductivity. Furthermore, by adopting the effective medium approximationmodel and finite element method, there exists a critical graphenelength where the overall thermal conductivities are equal for thefunctionalized and pristine graphene. Finally, the distribution stateof graphene is emphasized to be more vital in determining the overallthermal conductivity than the generally accepted interfacial thermalconductivity.

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