Construction of core-shell BN-OH@Fe3O4@PAn nanocomposite with ultra-wide microwave absorption and efficiency thermal management

As electronic device integration and power density increase, materials must have brilliant microwave ab-sorption properties and thermal conductivity to solve electromagnetic wave pollution and thermal man-agement problems. In this work, we attempt to construct core-shell hydroxylated boron nitride nanosheets (BN-OH) @Fe3O4@PAn (BFeA) nanocomposites by chemical synthesis and in-situ growth design. The ex-cellent magnetic properties of Fe3O4 and the good electrical conductivity of PAn can form magnetic loss and electrical loss centers to play a synergistic effect in improving microwave absorption capacity. Meanwhile, with the wave-transmitting material BN-OH as the core, the electromagnetic waves can be reflected multiple times within the absorber, which further enhances the microwave absorption capability of BFeA. As a result, the minimum reflection loss (RLmin) of the composites can reach - 49.85 dB at 11.36 GHz, and the effective microwave absorption bandwidth (RL < -10 dB, EAB) is close to 8 GHz (8.5-16.5 GHz) at a thickness of 3 mm. Simultaneously, to improve the thermal conductivity (TC) of the BFeA and reduce the interfacial thermal resistance, we use hydroxyl and dopamine as the interface linking agent at the interfaces of BN-OH and Fe3O4, and Fe3O4 and PAn, respectively. In this case, the TC of BFeA-2 reaches 0.98 W (m K)-1 at a total BN-OH content of only 13 wt. %, nearly 4 times that of the raw material (Fe3O4). This work can provide a reference for developing materials with dual functions of thermal management and microwave absorption.(c) 2022 Elsevier B.V. All rights reserved.