A facile route was proposed to synthesize polyaniline (PANI) uniformly deposited on bagasse fiber (BF) via a one-step in situ polymerization of aniline in the dispersed system of BF. Correlations between the structural, electrical, and electromagnetic properties were extensively investigated. Scanning electron microscopy images confirm that the PANI was coated dominantly on the BF surface, indicating that the as-prepared BF/PANI composite adopted the natural and inexpensive BF as its core and the PANI as the shell. Fourier transform infrared spectra suggest significant interactions between the BF and PANI shell, and a high degree of doping in the PANI shell was achieved. X-ray diffraction results reveal that the crystallization of the PANI shell was improved. The dielectric behaviors are analyzed with respect to dielectric constant, loss tangent, and Cole-Cole plots. The BF/PANI composite exhibits superior electrical conductivity (2.01 ± 0.29 S·cm), which is higher than that of the pristine PANI with 1.35 ± 0.15 S·cm. The complex permittivity, electromagnetic interference (EMI), shielding effectiveness (SE) values, and attenuation constants of the BF/PANI composite were larger than those of the pristine PANI. The EMI shielding mechanisms of the composite were experimentally and theoretically analyzed. The absorption-dominated total EMI SE of 28.8 dB at a thickness of 0.4 mm indicates the usefulness of the composite for electromagnetic shielding. Moreover, detailed comparison of electrical and EMI shielding properties with respect to the BF/PANI, dedoped BF/PANI composite, and the pristine PANI indicate that the enhancement of electromagnetic properties for the BF/PANI composite was due to the improved conductivity and the core-shell architecture. Thus, the composite has potential commercial applications for high-performance electromagnetic shielding materials and also could be used as a conductive filler to endow polymers with electromagnetic shielding ability.

necessary features has captured enormous scientific attentions.In particular, intrinsically conductive polymers (ICPs) have gained a special status among the promising EMI shielding materials. Among the large family of ICPs, polyaniline (PANI) is one of the prominent polymers, primarily owing to its fascinating properties, such as high electrical conductivity, ease of fabrication, unique controlled chemical and physical properties, as well as low cost. [3] Recently, PANI-based composite has aroused great interest due to the magnified or enhanced electromagnetic properties compared to their bulk counterpart. [4] Various components, such as carbon material, barium titanate (BaTiO 3 ), and bagasse fiber have been adopted to prepare the composites. For example, multi-walled carbon nanotube (MWCNT)/PANI nanocomposites possess a total EMI shielding effectiveness (SE) of ≈39.2 dB at the thickness of 2.0 mm, which is attributed to the synergistic effect of two complementary MWCNT and PANI phases. [5] Due to the optimized dielectric and electrical properties, an excellent SE of 71.5 dB was achieved for BaTiO 3 /PANI nanocomposites with the thickness of 2.7 mm. [6] Compared to pristine PANI, the core-shelled bagasse fiber@PANI composite exhibits immense potential for EMI shield with higher attenuation performance due to the synergistic and interfacial effects. [4b] It is noteworthy that in above cases the structure of PANI is a key parameter that determines its properties and application. Therefore, the delicate regulation and control of highly ordered PANI structures are highly desirable.On the other hand, inspired by natural materials, the designed helical structures endow materials the unique electrical and magnetic performance. Motojima et al. reported the microwave can be significantly attenuated by the helical structure, because of the effective generation of an inductive current. [7] Most recently, Yang et al. reported that PANI with a helical superstructure was produced by co-self-assembly process combined with emulsion droplets methods. The enhanced microwave absorption ability was achieved due to the supramolecular chirality. [8] So, the helical structure is expected to produce excellent EMI shielding performances. But as of yet, sparse research has concentrated on the effect of spiral structure on the shielding properties of PANI-based composites and their underlying mechanism. Furthermore, the EMI shielding capability of the PANI-based helical composite lacks sufficient theoretical Herein, a unique, 3D helical composite with excellent electromagnetic interference (EMI) shielding capability is fabricated. The alkali treated natural cotton fiber (NaCF) is adopted as the helical templet. The compacted polyaniline (PANI) clusters are grafted over NaCF surface via in situ polymerization technology. The correlation between structure and electromagnetic characteristics is investigated in details. The high doping degree and high crystalline phase of PANI coating layer results in the enhanced electrical conductivit...

Development of highly efficient electromagnetic interference (EMI) shielding materials with tunable properties is essential for the modern electronics industry against severe electromagnetic pollution. Herein, a series of novel heterostructured bagasse fiber/polyaniline (BF/PANI) composites are successfully synthesized via a facile in situ polymerization method and both their EMI shielding effectiveness (SE) and mechanisms were analyzed experimentally and theoretically. The results show that the conductivity and EMI shielding properties of BF/PANI composites can be tailored by adjusting the component, microstructure, and electromagnetic parameter, which can be easily tuned by modulating the weight ratio of aniline monomer and BF. More significantly, the BF/PANI heterostructures exhibit remarkable enhanced EMI shielding capabilities compared with the pristine PANI. The BF/PANI heterostructure prepared with an aniline volume of 7 mL shows an electrical conductivity of 6.07 S·cm–1 and the best EMI shielding capabilities of 35.73 dB. The excellent microwave attenuation capacity can be attributed to the cooperation of interface polarization, conductivity, skin depth effect, and the novel heterostructure. Considering their fascinating performance, these BF/PANI composites are proving to be the promising candidates as highly efficient EMI shielding materials.

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