Exceptional Thermal Conductance across Hydrogen‐Bonded Graphene/Polymer Interfaces

Abstract

the exceptional thermal properties of graphene and nanotubes, thereby reducing the overall conductivities of the nanocomposites.To improve the interfacial thermal conduction, interfaces between dissimilar materials need to be engineered for reduced phonon scattering. Current approaches include, but are not limited to, controlling interfacial adhesion, [16][17][18] improving interfacial stiffness, [ 19,20 ] strengthening interfacial interactions, [ 21,22 ] and manipulating phonon modes. [23][24][25] For graphene/polymer nanocomposites, in particular, the interfacial thermal transport can be improved by changing the orientation of few-layer graphene, [ 8 ] grafting graphene with polymer chains, [ 26 ] and functionalizing graphene for tailored phonon modes. [ 27 ] In the fi rst approach, the improvement results from the high thermal conductivity of graphene/graphite in the basal plane along with the enhanced interfacial coupling. [ 28,29 ] In the other two, the polymer chains and functional groups serve as thermal bridges to couple the vibrational modes of graphene with those of the polymeric matrix, thereby minimizing phonon scattering and improving thermal transport.Despite the progress, little attention has been drawn to the manipulation of bonding strength at the graphene/polymer interfaces for improved heat transfer. In most nanocomposites, [ 26,27 ] molecular interactions at material interfaces are dominated by van der Waals forces. It is hypothesized that, interfacial heat transfer can be signifi cantly improved by enabling hydrogen bonds at the interfaces. The hypothesis is made based on three reasons. First, the strength of hydrogen bonds ranges from 10 to 190 kJ mol -1 , 1-2 orders of magnitude higher than that of the van der Waals interactions. [ 30,31 ] Second, recent advances in surface treatment [ 32 ] have made it relatively simple to anchor hydrogen-bond-capable chemical groups to the graphene surfaces to enable hydrogen bonds with many polymers. Third, hydrogen-bond-facilitated thermal conduction has been recently demonstrated in several other material systems including crystalline polymer nanofi bers, [ 33 ] amorphous polymer blends, [ 34 ] along with silk β-sheets [ 35,36 ] and α-helices. [ 37,38 ] However, the use of hydrogen bonds to improve the interfacial thermal transport at graphene/polymer interfaces has not yet been reported.Here, using reverse nonequilibrium molecular dynamics along with various vibrational mode and structural analysis tools, we demonstrate that the presence of hydrogen bonds Ineffective heat transfer between dissimilar materials of drastically different properties is a challenge for many areas including nanoelectronics and nanocomposites. Here, using atomistic simulations, it is demonstrated that the thermal conductance across the interfaces between graphene and poly(methyl methacrylate) (PMMA) can be improved by 273% by introducing hydrogen-bond-capable hydroxyl groups to the interfaces. Stronger than van der Waals interactions, the hydrogen bonds are found to improve t...

Enhancement of Thermal Boundary Conductance of Metal–Polymer System

“…It is well established that TBC depends on the bonding strength at the interface, which has been predicted by analytical models [36], molecular dynamics simulations [37][38][39][40][41] and experiments [42][43][44][45]. In this study, the observed increase in G is most likely caused by an increase in adhesion between the metal and polymer.…”

Hierarchically hydrogen-bonded graphene/polymer interfaces with drastically enhanced interfacial thermal conductance

“…G-32PVA), interfacial thermal conductance is improved to be 6.22 times that of the pristine graphene/PMMA interface (551.53 MW m -2 K -1 versus 88.66 MW m -2 K -1 ). Compared with the previously studied hydroxyl-functionalized graphene/PMMA interface which features a 2D hydrogen bond layer, 27 the present system with a 3D hierarchical hydrogen bond network improves the interfacial thermal conductance further by 1-2 times, especially when X < 16. As demonstrated in Fig.…”

“…As a result, grafting PVA chains improves interfacial thermal conductance, with more heat conducted through the highly efficient PVA-PMMA channel; while at low grafting densities, most heat is conducted through the less efficient graphene-PMMA channel. A direct proof of this conclusion can be obtained by computing integrated autocorrelation of interfacial heat power 27 which is proportional to interfacial thermal conductance according to Green-Kubo fluctuation theorem. Fig.…”

Magnesium Hydride Nanoparticles Self-Assembled on Graphene as Anode Material for High-Performance Lithium-Ion Batteries

“…33,34 Besides, recent theoretical and experimental studies have proven that the interfacial interactions between PMMA and GR exhibit enhanced electrical conductivity and mechanical and thermal properties. [33][34][35] More evidences can be found in the FTIR spectra (Figure 4b), which demonstrates a broad and strong peak at ~3443 cm −1 assigned to a strong hydrogen bonding in comparison with PMMA spectrum; meanwhile, the typical absorptions in the stretching regions of PMMA at ~1731 cm −1 (C=O) and 1272~1150 cm −1 (C-O-C) 36,37 generate a red shift to ~1635 cm −1 and 1232~1120 cm −1 , respectively. Those favorable interactions between PMMA and GMH composite not only ensure that active materials could be tightly attached to current collector, but also buffer the volume expansion and internal strain of active materials, which is beneficial to maintain the structural integrity of electrode.…”