UV-Curable 3D-Printable Microwave-Absorbing Material with a Sword-Sheath Structure Based on Multiwalled Carbon Nanotube/Polypyrrole Nanotube/Fe3O4 Composites

Multiwalled carbon nanotube (MWCNT)/polypyrrole nanotube (PPyNT)/triiron tetraoxide (Fe 3 O 4 ) composites with a sword-sheath structure are added to a UV-curable resin to form a unique highly microwave-absorbing material with a low absorbent content. Specifically tailored for high-precision stereolithography three-dimensional (3D) printers, the low absorbent content ensures an efficient curing and molding of the photosensitive resin. The conducting polymer polypyrrole is coated on the MWCNTs via free-radical polymerization, forming a sheath structure. The initiator of the free-radical polymerization, FeCl 3 , is converted into Fe 3 O 4 and loaded onto the sheath structure. This ternary composite material is uniformly dispersed in the photosensitive resin with interconnected sword-sheath structures, ensuring a favorable dielectric loss performance even at a low absorbent content. Importantly, the material exhibits both dielectric loss and magnetic loss properties. Using a UV-cured microwave-absorbing material with an absorbent content of 0.5 wt%, an electromagnetic loss of −22.5 dB can be achieved with a thickness of 1 mm. This UV-cured microwave-absorbing material facilitates the high-precision 3D printing of microwave structures with various intricate shapes, broadening the application scope of microwave-absorbing materials.