Preparation of MWCNTs/Si3N4/PPy ternary composites via click chemistry and wave-absorbing properties

In this paper, MWCNTs/Si 3 N 4 binary composites were synthesized using a chemical click method, establishing a foundation for the in situ polymerization of MWCNTs/Si 3 N 4 /PPy ternary composites. The morphology, electrical conductivity, and electromagnetic parameters of the composites were characterized using scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and infrared analysis. The wave-absorbing properties of the composites were assessed with a vector network analyzer. The impact of varying feeding ratios on the absorption properties of the composites was investigated. The results indicated that as the amount of PPy increased, the minimum reflection loss of the nano-hybrid materials initially decreased before subsequently increasing. When the feeding ratio of MWCNTs: Si 3 N 4 : PPy was set at 2:1:4 and the thickness of the absorption layer was 2.5 mm, the minimum reflection loss (RL min ) reached −40.14 dB, while the maximum absorption bandwidth (EAB max ) attained 6.88 GHz (d = 2.0 mm). Compared to MWCNTs/Si 3 N 4 binary materials, the ternary materials demonstrated enhanced electromagnetic absorption capabilities. The numerous heterogeneous interface formed by MWCNTs, Si 3 N 4 , and PPy facilitates charge accumulation, creating a structure similar to a capacitor that induces interface polarization and attenuates electromagnetic waves (EMWs) by aligning polar bonds or charges in response to an alternating electric field. Additionally, the MWCNTs/Si 3 N 4 binary nanohybrid materials exhibit a larger surface area following PPy coating, which further enhances impedance matching, extends the propagation distance of EMWs, and improves their dissipation. These research results are of great significance for the production of absorbent composite materials and provide new ideas for the design of absorbent materials.