Thermally conducting yet electrically insulating epoxy nanocomposites containing aluminum@electrochemically exfoliated graphene hybrid

The development of miniaturized and highly integrated microelectronic products has motivated the current importance of synthesizing heat-dissipation materials with high thermal conductivity and excellent electrical insulation. Although graphene is attractive for improving the thermal conductivity of polymers owing to its high aspect ratio and outstanding thermal conductivity, it significantly deteriorates electrical insulation capability, limiting its practical application in polymer composites for thermal management of electronics and systems. In this work, we used planetary ball milling to synthesize a hybrid powder Al@EEG consisting of electrochemically exfoliated graphene (EEG) and surface-passivated aluminum particles. This ball milling prevents contact between graphene sheets by uniformly dispersing EEG in Al matrices without the conventional surface modification or chemical treatment process of graphene, thereby imparting thermal conductivity and electrical insulation to the hybrid powder. The resulting epoxy composite, containing 35- wt% Al@EEG hybrid, retains an electrical resistance of 1014 Ω·cm or higher and a thermal conductivity of 1.43 W m−1 K−1, which is 499% higher than that of neat epoxy. The as-designed material points the way to polymer-based, thermally conductive, electrically insulating composites for various electronic components such as printed circuit boards and light-emitting diode driver cases.