Nitrene functionalization as a new approach for reducing the interfacial thermal resistance in graphene nanoplatelets/epoxy nanocomposites

摘要

Conventional functionalization methods, such as oxidation, can be very damaging for the nanocarbons microstructure and therefore detrimental for their intrinsic thermal conductivity. In this study, nitrene chemistry was investigated as a non-disruptive approach for the covalent functionalization of graphene nanoplatelets (GNP). The nitrene precursor was synthesized and thermally decomposed in situ to functionalize GNP (cm-GNP). Temperature and solvents of reaction were found to have profound impact on the functionalization yield. Epoxy nanocomposites were then prepared with pristine, oxidized and cm-GNP. Influence of dispersion methodology was crucial for cm-GNP, as sonication was found to damage the functionalization. Oxidation caused a dramatic drop in thermal conductivity compared to pristine GNP. By contrast, nitrene chemistry produced the highest thermal conductivity enhancement. Finally, epoxy nanocomposites thermal conductivity results were correlated and discussed in light of SEM and micro-computed X-ray tomography (mCT) analyses. The mCT highlighted new features, such as micro-voids surrounding pristine GNP in epoxy nanocomposites, which are invisible with conventional methods. It was found that functionalization not only enhanced the dispersion but also improved GNP/polymer interactions. Moreover, mCT clearly demonstrated that nitrene functionalization eliminated the micro voids surrounding the fillers in the epoxy nanocomposites. (C) 2020 Elsevier Ltd. All rights reserved.