Lattice-filler dual-gradient and hierarchical porous architectures customized by multiple-nozzle 3D printing towards excellent absorption-dominant electromagnetic interference shielding

Abstract

Exploiting high-performance absorption-dominant electromagnetic interference (EMI) shielding composites is ungently desired yet challenging for minimizing the secondary electromagnetic radiation pollution. Herein, lattice-filler dual-gradient Fe₃O₄/carbon nanotube/polyurethane&MXene (Fe₃O₄/CNT/PU&MXene; DGFCP&M) composite frames with a positive gradient of functional filler and a negative gradient of lattice size were successfully fabricated by a powerful multiple-nozzle immersion-precipitation 3D printing (ip3DP) technology. The insulative top layer of DGFCP&M frames with larger lattice pores plays a role as an impedance matching layer to mitigate the reflection of electromagnetic wave (EMW). Nevertheless, the highly conductive bottom layer of MXene with non-lattice structure acts as a reflective layer to reflect EMW back to the interior of DGFCP&M frames. Moreover, hierarchical porous structures (lattice macropores and filament micropores) can prolong the transmitting path to enhance the attention of EMW energy. In consequence, excellent SE_T of 72.7 dB and A of 0.62 are achieved for DGFCP&M-8 composite frame at EMW incident from top surface, both of which are superior to those of homogenous and single-gradient composite frames. Furthermore, visual simulations intuitively verify that the lattice-filler dual-gradient composite frame has an excellent absorption-dominant EMI shielding performance. The construction of lattice-filler dual-gradient architectures based on multiple-nozzle ip3DP provides a valuable insight into the fabrication and adjustment of absorption-dominant EMI shielding composites for the promising application in next-generation flexible and portable electronic devices.