A new method for an efficient porous carbon/Fe_3O_4 composite based electromagnetic wave absorber derived from a specially designed polyimide

摘要

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 (T-g, 404 degrees C) and the low initial thermal decomposition temperature (394 degrees 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.