Flexible Warp-Knitted Metal Mesh-Based Composites: An Effective EMI Shielding Material with Efficient Joule Heating

Abstract

The critical electromagnetic wave pollution problem from the fast-growing electronic devices drives the enormous requirement and rapid advancement of electromagnetic interference (EMI) shielding material and technology. Herein, inspired by the shielding effectiveness of warp-knitted stainless steel (SS) meshes composed of ultrafine metal wires, we endeavor to design the metal mesh-based thermoplastic polyurethane (TPU)/carbon nanotube (CNT) composites. The effects of different CNT filler concentrations and different TPU/CNT coating thicknesses on the electrical conductivity, EMI shielding, thermal management, and mechanical performance of metal mesh-based composites have been investigated explicitly. The heterogeneous composites combine the microwave-reflecting characteristic of the metal mesh and the microwave-absorbing features of the CNT nanofiller. An effective EMI shielding efficiency of 22.01 dB in the X-band frequency (8.2–12.4 GHz) is achieved, and the corresponding shielding efficiency enhancement exceeds 263% relative to pure metal mesh. The composite shows a stable EMI shielding efficiency after repeated 1000 bending–relaxing deformations. Moreover, the synergistic network shows a superb electrical conductivity of 1348 S/m and an excellent electrothermal conversion capability of 91.1 °C (3 V). The incorporation of CNTs helps form interconnected conductive and reinforcement networks within the TPU matrix upon the SS warp-knitted mesh substrate, which improves the mechanical performance, EMI shielding, electrical conductivity, and electrothermal conversion capability. Therefore, the proposed warp-knitted metal mesh-based TPU/CNT composites provide great potential in the next-generation large-scale and stretchable construction canopy applications.