Dual-Functional Graphene Composites for Electromagnetic Shielding and Thermal Management

The synthesis and characterization of epoxy-based composites with few-layer graphene fillers, which are capable of dual-functional applications, are reported. It is found that composites with certain types of few-layer graphene fillers reveal an efficient total electromagnetic interference shielding, SEtot approximate to 45 dB, in the important X-band frequency range, f = 8.2 -12.4 GHz, while simultaneously providing high thermal conductivity, K approximate to 8 W m(-1) K-1, which is a factor of x35 larger than that of the base matrix material. The efficiency of the dual-functional application depends on the filler characteristics: thickness, lateral dimensions, aspect ratio, and concentration. Graphene loading fractions above the electrical and thermal "percolation thresholds" allow for strong enhancement of both the electromagnetic interference shielding and heat conduction properties. Interestingly, graphene composites can block the electromagnetic energy even below the electrical percolation threshold, remaining electrically insulating, which is an important feature for some types of thermal interface materials. The dual functionality of the graphene composites can substantially improve the electromagnetic shielding and thermal management of airborne systems while simultaneously reducing their weight and cost.