Three-phase PANI@nano-Fe3O4@CFs heterostructure: Fabrication, characterization and investigation of microwave absorption and EMI shielding of PANI@nano-Fe3O4@CFs/epoxy hybrid composite

In this work, a three phase carbon fiber (CF)-based electromagnetic (EM) wave absorbing and EM interference (EMI) shielding heterostructure was fabricated through a layer by layer assembly. The nano-Fe3O4 particles were deposited on CFs via a modified multi-step electrophoretic deposition (EPD). The PANI@nano-Fe3O4@CFs heterostructures were prepared using an in situ polymerization process of polyaniline (PANI) on nano-Fe3O4@CFs in HCl solution. The results showed that the PANI@nano-Fe3O4@CFs mats with a layer by layer (LBL) assembly were successfully fabricated. The saturated magnetization (Ms) of the as-synthesized nano-Fe3O4 powder decreased from 72.612 to 8.934 emu/g for the nano-Fe3O4@CFs and from 8.934 to 0.191 emu/g for the PANI@nano-Fe3O4@CFs mats due to the reduction in the effective mass/volume percentage of nano-Fe3O4 particles in the composites. The fabricated epoxy-based hybrid composites filled with PANI@nano-Fe3O4@CFs segments exhibited both of the dielectric and magnetic losses at the 8.2-18 GHz frequency range. The composite containing 1 wt% of PANI@nano-Fe3O4@CFs with the thickness of 1.5 mm showed a maximum reflection loss (RL) value of −11.11 dB with an effective absorption bandwidth of about 6 GHz in the frequency range of 8.2-18 GHz. Also, the sample filled with 5 wt % of EM wave absorbing segments with the thickness of 3 mm demonstrated an EMI shielding effectiveness (SE) value of 29 dB at the same frequency range.