3D printing of ultralight MWCNT@OCNF porous scaffolds for high-efficiency electromagnetic interference shielding

Towards the difficulties of traditional processing technology in loading high-concentration functional fillers to realize the target electromagnetic interference shielding (EMI SE) performance, and constructing the arbitrary-designated architectures for serving advanced electronics, this work innovatively formulated a functional multi-walled carbon nanotubes@cellulose nanofibers (MWCNT@OCNF) ink for direct ink writing (DIW) 3D printing, which not only possessed high freedom on the proportion of functional particles, but also imparted to the ideal rheological performance for 3D printing. Based on the pre-programmed printing trajectories, a series of porous scaffolds featuring exceptional functionalities were architected. Particularly for the electromagnetic waves (EMWs) shielding behaviors, the optimized one with "full-mismatched" architecture posed the ultralight structure (0.11 g/cm³) and superior SE performance (43.5 dB) in the X-band frequency region. More encouragingly, the 3D-printed scaffold with hierarchical pores possessed the ideal electromagnetic compatibility on EMWs signal, where the radiation intensity generated by EMWs signal fluctuated in a step pattern in 0 and 1500 μT/cm² as loading and unloading scaffolds. Overall, this study paved a novel path for the formulation of functional inks to print lightweight, multi-structure, and high-efficiency EMI SE scaffolds for the next-generation shielding elements.