title: Tuning interfacial thermal conductance of graphene embedded in soft materials by vacancy defects.
abstract: Nanocomposites based on graphene dispersed in matrices of soft materials are promising thermal management materials. Their effective thermal conductivity depends on both the thermal conductivity of graphene and the conductance of the thermal transport across graphene-matrix interfaces. Here, we report on molecular dynamics simulations of the thermal transport across the interfaces between defected graphene and soft materials in two different modes: in the "across" mode, heat enters graphene from one side of its basal plane and leaves through the other side; in the "non-across" mode, heat enters or leaves graphene simultaneously from both sides of its basal plane. We show that as the density of vacancy defects in graphene increases from 0% to 8%, the conductance of the interfacial thermal transport in the "across" mode increases from 160.4 ± 16 to 207.8 ± 11 MW/m(2) K, while that in the "non-across" mode increases from 7.2 ± 0.1 to 17.8 ± 0.6 MW/m(2) K. The molecular mechanisms for these variations of thermal conductance are clarified using the phonon density of states and structural characteristics of defected graphene. On the basis of these results and effective medium theory, we show that it is possible to enhance the effective thermal conductivity of thermal nanocomposites by tuning the density of vacancy defects in graphene despite the fact that graphene's thermal conductivity always decreases as vacancy defects are introduced.
authors.affiliation: Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Mechanical Engineering, Clemson University, Clemson, South Carolina 29634, USA.
authors.forename: Chongze
authors.initials: C
authors.lastname: Hu
authors.affiliation: Center for Nanophase Materials Sciences and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
authors.forename: Jingsong
authors.initials: J
authors.lastname: Huang
authors.affiliation: Center for Nanophase Materials Sciences and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
authors.forename: Bobby G
authors.initials: BG
authors.lastname: Sumpter
authors.affiliation: Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Qiao