Enhanced electromagnetic interference shielding via surface-bound molecules and synergistically amplified polarization and triboelectrification

Abstract

Achieving high-performance electromagnetic interference (EMI) shielding materials with ultra-low reflectivity, minimal volume, and light weight is challenging. This study addresses this by introducing a nanofiber (NF)-based structure composed of MXene nanoflakes and ferroelectric barium titanate oxide (BTO) nanoparticles embedded within polyurethane (PU) fibers, and surface-bound branched polyethyleneimine (PEI(b)) on the NFs. This design enhances the flexibility and lightness of the EMI shielding materials while effectively minimizing reflectivity. A key approach in this study is the functionalization of the NFs with branched polyethyleneimine (PEI(b)), which reduces reflectivity and enhances EMI shielding effectiveness (SE). The surface-bound molecules increase the effective surface area, improving the absorption efficiency of incident electromagnetic waves without adding weight or volume. Additionally, the surface-bound PEI(b) molecules synergistically enhance the polarization of the embedded BTO nanoparticles and amplify the triboelectric charging effect, crucial for achieving ultra-low reflectivity and high EMI SE. Combining the optimized composite NF design with these enhancement methods, this study achieves significant advancements in EMI SE, reaching an EMI SE of 72 dB, an absolute EMI SE (SSEt) of 28,460 dB·cm²g−1, and a reflectivity of 0.09, all without increasing weight or volume. This approach exemplifies how the strategic application of surface-bound molecules can enhance EMI shielding effectiveness and achieve ultra-low reflectivity through the effective expansion of the absorption surface and synergistic enhancement of piezoelectric and triboelectric effects.