Nitrogen-doped carbon encapsulated Al2O3 composites for microwave absorption and heat conduction

Abstract

Highly efficient multifunctional materials that exhibit strong microwave absorption and elevated heat conduction are crucial for tackling electromagnetic interference and heat accumulation in miniaturized and integrated electronic systems. Nevertheless, it is difficult to overcome the inherent incompatibility between microwave absorption and heat conduction using simple physical blending, which poses a significant challenge to their concurrent enhancement. Herein, Al₂O₃/nitrogen-doped carbon (Al₂O₃/NC) composites are fabricated via a thermal pyrolysis strategy and dispersed within thermoplastic polyurethane (TPU). The Al₂O₃/NC/TPU composites display an optimal reflection loss of −63.96 dB at 2.20 mm and an effective absorption bandwidth of 3.8 GHz at 2.37 mm with a filler loading of 60 wt%. Besides, their thermal conductivity reaches up to 0.65 W m⁻¹ K⁻¹ at the same filler content. The outstanding microwave absorption performance benefits from effective impedance matching, multiple reflections and scatterings and strong dielectric loss. Furthermore, the intercross-linked networks enhance the overall heat conduction performance. This study reveals a straightforward and efficient approach for developing advanced materials that combine microwave absorption and heat conduction, offering immense potential for applications in modern electronics.