Fabricating and Tailoring Polyaniline (PANI) Nanofibers with High Aspect Ratio in a Low-Acid Environment in a Magnetic Field

In a 0.010 m HCl solution, we successfully transformed irregular polyaniline (PANI) agglomerates into uniform PANI nanofibers with a diameter of 46-145 nm and a characteristic length on the order of several microns by the addition of superparamagnetic Fe₃O₄ microspheres in a magnetic field. The PANI morphological evolution showed that the PANI nanofibers stemmed from the PANI coating shell synthesized on the surface of the Fe₃O₄ microsphere chains. It was found that the magnetic field could optimize the PANI nanofibers with a narrow diameter size distribution, and effectively suppressed secondary growth. When compared with other microspheres (like silica and polystyrene), only the use of superparamagnetic Fe₃O₄ microspheres resulted in the appearance of PANI nanofibers. Attempts to form these high-quality PANI nanofibers in other concentrations of HCl solution were unsuccessful. This deficiency was largely attributed to the inappropriate quantity of aniline cations. Tailor-made fibers: A facile method to prepare uniform polyaniline (PANI) nanofibers with high aspect ratio has been described. A magnetic field, superparamagnetic Fe₃O₄ microspheres, and an appropriate concentration of HCl solution (0.010 m) were found to be paramount for the formation of PANI nanofibers (see figure).