Synthesis of MWCNTs/Si₃N₄ Nanocomposites Via Click Chemistry and Electromagnetic Wave-Absorption Properties

This study details microwave-absorbing materials made of multi-walled carbon nanotubes (MWCNTs) and silicon nitride (Si₃N₄). The synthesis of MWCNTs/Si₃N₄ nanocomposites (NCs) involves combining alkyne-functionalized multi-walled carbon nanotube (MWCNTs-ALK) nanoparticles (NPs) with azide-functionalized silicon nitride (Si₃N₄–N₃) NPs through a click reaction. In order to analyze the morphology and structure of the MWCNTs/Si₃N₄ NCs, scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray diffraction, and infrared analysis techniques are employed. The electromagnetic properties of the NCs are evaluated using a vector network analyzer. The results indicate when this feeding ratio of MWCNTs-ALK and Si₃N₄–N₃ was 1:2 and a matching thickness of 3.0 mm at 6.82 GHz, the minimum reflection loss reaches − 30.7 dB. Additionally, with a feeding ratio of 1:1 and a matching thickness of 1.5 mm, the bandwidth below − 10 dB ranges from 11.6 to 15.8 GHz. The compositions of MWCNTs/Si₃N₄ synthesized by click reactions indicate that, compared to physical mixed samples, our material has superior wave-absorbing properties. This improvement can be attributed to the covalent bonding between MWCNTs and Si₃N₄ facilitated by the click reaction, resulting in enhanced dielectric loss and impedance matching. The results of this study have significant implications for the processing of composite microwave-absorbing materials and offer novel insights into the design of multifunctional microwave-absorbing materials.