Enhanced\nX‑Band Electromagnetic-Interference Shielding Performance of\nLayer-Structured Fabric-Supported Polyaniline/Cobalt–Nickel\nCoatings

Abstract

Despite tremendous\nefforts, fabrication of lightweight conductive fabrics for high-performance\nX-band electromagnetic-interference (EMI) shielding remains a daunting\ntechnical challenge. We herein report an ingenious and efficient strategy\nto deposit polyaniline/cobalt–nickel (PANI/Co–Ni) coatings\nonto lyocell fabrics that involves consecutive steps of in situ polymerization\nand electroless plating. The PANI–Co−Ni ternary-component system successfully induced a synergistic\neffect from EM wave-absorption and EM wave-reflection and, moreover,\nupgraded the match level between magnetic loss and dielectric loss.\nBy the judicious control of polymerization cycles and plating time,\nlow-weight fabric-supported PANI/Co–Ni composites (with PANI\nand Co–Ni loading of 2.86 and 3.99 mg·cm^–2, respectively) were prepared, which displayed relatively high EMI\nshielding effectiveness (SE) (33.95–46.22 dB) when compared\nto their single peers (PANI-coated fabric and Co–Ni-coated\nfabric) or even the sum of them. Inspired by the so-called “1\n+ 1 > 2” phenomenon, here we demonstrated that there was\nan EMI SE enhancement effect in this conductive polymer/metal system\nthat may be associated with interphase chemical and/or physical interactions.\nFurther analysis revealed that this EMI SE enhancement effect was\nevident under circumstances of relatively low metal content and became\nweak with the increase of metal content. The mechanisms involved were\ninterpreted through a series of fundamental measurements, including\nFourier transform infrared spectroscopy (FTIR), X-ray photoelectron\nspectroscopy (XPS), X-ray diffraction (XRD), field emission-scanning\nelectron microscopy (FE-SEM), and vector network analysis (VNA). The\nlinkage between PANI and Co–Ni coatings was in the form of\nCo–N/Ni–N, which mimics the atomic configuration occurring\nin cobalt porphyrins. The Co–N/Ni–N configuration strengthened\nthe interphase adhesion and thus resulted in shielding fabrics with\nhigh durability for practical applications.