LAUSR

Abstract Natural, electrical insulating bamboo fiber (BBF) was selected as cost-effective frameworks to fabricate electromagnetic interference (EMI) shielding composites. The compacted polyaniline (PANI) layer was formed on the surface of BBF through an in-situ polymerization process. The formation of the continuous PANI layer was attributed to the interaction between the aniline monomers and BBF surface. Three-dimensional electromagnetic reflection cavities were facilely constructed by this unique architecture. The electromagnetic properties are extensively investigated with respect to electrical conductivity, complex permittivity and permeability, loss tangent, and Cole-Cole analysis. By manipulating the mass ratio of BBF with different size, BBF@PANI possessed a high electrical conductivity of 8.99 ± 0.43 S/cm. Combined with the results of skin depth, attenuation constant, also comparisons of experimental results and theoretical predictions, it was found that besides the conductivity and dielectric loss, the compacted microwave reflection cavity could also boost the EMI shielding effectiveness (SE). By introducing effective multiple reflections, the absorption ability was enhanced. The EMI SE could even reach 45.0 dB with only 0.4 mm thickness. The attenuation of microwave was predominantly governed by an absorption mechanism. Furthermore, the SE per unit thickness could be as high as 1125.0 dB/cm, which is much higher than those other types of PANI-based materials. With outstanding EMI shielding performance, these BBF@PANI heterostructures offer promising prospects of lightweight, cost-effective and excellent performance EMI shields. We firmly believe that this research will be an effective platform for the development of green electromagnetic attenuators in the future.