Architecting Three-Dimensional Networks in Carbon Nanotube Buckypapers for Thermal Interface Materials

Carbon nanotube (CNT) buckypaper, which has large specific surface area and tunable network structures, shows great potential in the application of heat dissipation for high power electronic devices. In this article, we report that the heat conduction in a buckypaper depends greatly on CNT network formation, in which CNT structures, lengths, and orientations are important issues. The buckypaper composed of multiwalled CNTs with large diameter (around 50 nm) and suitable length (1-10 mu m) shows lower thermal impedance compared with those made by longer CNTs with smaller diameter. The thermal impedance of such buckypapers can be reduced to 0.27 cm(2).K/W, lower than that of commercialized graphite foil and thermal grease. Thus, the buckypaper may serve as a promising candidate for advanced thermal interface materials. Detailed structural characterization indicates that the three-dimensional networks of buckypapers, with CNT orientations perpendicular to the surfaces, result in both the reduction of thermal contact resistance and the enhancement of heat conduction along the thickness.