A new method for an efficient porous carbon/Fe3O4 composite based electromagnetic wave absorber derived from a specially designed polyimide

Abstract

A new strategy was developed for the fabrication of the honeycomb-like porous carbon (HPC) material, involving a liquid-liquid phase separation process and a pyrolysis process. First of all, a novel polyimide containing benzothiazole moieties was designed and synthesized as the carbon precursor. Due to the high glass-transition temperature (Tg, 404 °C) and the low initial thermal decomposition temperature (394 °C) of this specially designed polyimide, the pore structure formed during the phase separation process was well maintained in the following pyrolysis process. As determined by SEM, the product has a honeycomb-like pore structure with a high uniformity. XRD and Raman spectra manifested the resulting carbon material possessed a disordered graphite structure, which can greatly contribute to its EM wave dissipation ability. After modifying HPC with Fe3O4 nanoparticles, the nanocomposites (HPC/Fe3O4) achieved an excellent EM wave absorption performance. At the absorber thickness of 5.5 mm, a minimum reflection loss (RL) value of −20.1 dB was achieved. Moreover, with the variation of the absorber thickness from 1.3 to 5.0 mm, the minimum RL curves in Ku band were all lower than −10 dB. These results demonstrated the polyimide could be an excellent precursor for the synthesis of porous carbon materials with controllable morphology. Additionally, HPC/Fe3O4 could be a promising material for applications in the field of EM wave absorption.