Facile synthesis of polyaniline nanostructures with effective electromagnetic interference shielding performance

Polyaniline (PANI) with different nanostructures has been synthesized through a simple chemical oxidation method without using any hard or soft templates. A correlation between structure, chemical construction, electrical conductivity, and electromagnetic shielding properties were extensively investigated. The obtained PANI nanostructures exhibit various morphologies by just simply changing the doping acids. The PANI doped with hydrochloric acid (denoted as PANI-HCl) and doped with camphorsulfonic acid (denoted as PANI-CSA) exhibite the “holothurian-like” morphology, while the PANI doped with phosphoric acid (denoted as PANI-H₃PO₄) presents the nanofiber structure. The “holothurian-like” structure showed larger diameters and length than the nanofibers. During the three samples, the PANI-CSA exhibits the highest electrical conductivity (1.28 ± 0.17 S cm⁻¹) due to the large oxidation extent, crystallinity, and crystallite size. An excellent electromagnetic interference (EMI) shielding effectiveness (SE) as 20.7 dB of PANI-CSA was achieved with the thickness of only 0.35 mm. All these samples present an absorption-dominated shielding mechanism. Moreover, the SE values obtained from the experiments are higher than the theoretical calculations. All these above results indicated that the EMI shielding performance and dielectric permittivity were strongly affected by the microstructure and the chemical construction. We believe that this one-step procedure represents a promising protocol to control the nanostructures and properties of PANI for applications as advanced EMI shielding materials.