Asymmetric layered structural design with segregated conductive network for absorption-dominated high-performance electromagnetic interference shielding

Abstract

Abstract Absorption-dominated electromagnetic interference (EMI) shielding composites with high shielding effectiveness (SE) and low reflection (R) is of particular interests for next-generation electronic devices, but it remains a great challenge. Herein, an ingenious approach is proposed to develop asymmetric thermoplastic polyurethane (TPU)/carbon nanotube (CNT)/Ag composites comprised of a segregated TPU/CNT composite layer and a conducting silver layer through the combination of electrostatic absorption, thermal-cladding, vacuum-assisted hot compression, and blade-coating methods. By high-speed mixing of charged CNT and TPU granules and vacuum-assisted compression molding, a segregated TPU/CNT composite layer with highly compacted CNT paths is constructed, which provides efficient electromagnetic wave absorption performance. Further introducing a silver coating serves as a reflection layer, resulting in a special “absorb-reflect-reabsorb” course when electromagnetic waves penetrate the asymmetric composite. The synergistic effects contribute to a preeminent EMI SE of 79.4 dB and SEA of 74.8 dB against the X-band at extremely low filler content (3.7 wt% CNTs and 0.04 wt% Ag) of the asymmetric TPU/CNT/Ag composites, which indicates 99.999999% EM waves are attenuated in the propagation process, and SEA contributes 94.2% to the total SE. Moreover, an R-value of 0.54 is reached because of the destructive interference between the reflected and incident EM waves. This work opens an avenue for the design and fabrication of EMI shielding CPCs with reliable absorption-dominated features and is highly promising for applications in next-generation electronic devices.