Boron Nitride- and Carbon Nanotube-Bridged Interfaces for Boosting Thermal Conduction and Electromagnetic Wave Absorption

Electromagnetic interference and heat accumulation issues induced by highly integrated electronic devices require advanced electromagnetic wave absorbing (EWA) materials with good thermal conductivity. However, such materials are currently lacking. In this work, boron nitride/nickel/carbon nanotube (BN/Ni/CNT) hybrids are synthesized via a simple one-step calcination method, and flexible BN/Ni/CNT/water polyurethane films (BN/Ni/CNT/WPU) are prepared by a knife coating process. These films achieve the dual-functional capability of efficiently dissipating heat and EWA performance. The thermal conductivity pathway and EWA performance can be optimized by easily adjusting the proportions of BN, Ni, and CNT in hybrids. The flexible BN0.66/Ni0.33/CNT7/WPU film with dual-functional ability yields a minimum reflection loss (RLmin) of −48.6 dB at 9.68 GHz with a thickness of 2.0 mm, and its through-plane thermal conductivity can reach 0.76 W/m·K. Such an attractive EWA performance is attributed to dielectric loss, magnetic loss, and moderate impedance matching, while the good thermal conductivity is a result of the constructed heat conduction channel induced by the combination of BN and CNTs. This study may provide an idea for designing next-generation materials with high EWA and thermal conductivity capabilities.