Preparation and electromagnetic shielding properties of conductive/magnetic filler composite nylon fabric

The rapid development of 5G communication and the Internet of Things (IoT) led to increasingly severe electromagnetic pollution, which posed a serious threat to the operation stability of electronic devices and human health. It was urgent to develop flexible, lightweight, eco-friendly, and high-efficiency electromagnetic interference (EMI) shielding fabrics for wearable electronic applications, while existing materials were limited by complex preparation processes, high cost, and insufficient shielding performance. Herein, we fabricated a series of EMI shielding composite fabrics using nylon fabric as the substrate, eco-friendly waterborne polyurethane (WPU) as the matrix, and acetylene black (AB) and ferroferric oxide (Fe 3 O 4 ) as conductive and magnetic functional fillers, via a facile coating method combined with a layer-by-layer pre-curing process. The effects of filler concentration, composite order and multi-layer gradient structure on the EMI shielding effectiveness (SE) of the composite fabrics were systematically investigated. The results showed that the optimal SE of single-filler coated fabrics reached 15.5 dB for the 5 wt% AB filled system and 3.5 dB for the 30 wt% Fe 3 O 4 filled system, respectively. By constructing a vertical gradient structure (AB-Fe 3 O 4 layered design), the SE of the binary composite fabric was enhanced to 19 dB, which realized a significant synergistic enhancement compared with single-filler systems. More importantly, after introducing conductive copper paint to form a three-layer gradient structure, the composite fabric achieved an excellent SE of EMI over 55 dB in the target frequency band. This work provided a facile and scalable strategy for the fabrication of high-performance flexible EMI shielding fabrics, and had promising application prospects in the field of wearable electronic protection.