Synthesis of PANI nanostructures with various morphologies from fibers to micromats to disks doped with salicylic acid

Shape-controllable polyaniline (PANI) nanostructures varying from fibers to micromats and disks were synthesized via a self-assembly process with salicylic acid (SA) as dopant. It has been achieved just by tuning the concentration of aniline, the mole ratio of SA to aniline, and the mole ratio of APS to aniline in the same reaction. The diameters of the fibers could be controlled from 30 to 400 nm by adjusting the concentration of aniline. Micromats of fibers would be formed by changing the mole ratio of SA to aniline. Disk-like PANI nanostructures were synthesized when decreasing the mole ratio of APS to aniline. Scanning electron microscopy and transmission electron microscopy were applied to investigate various kinds of morphologies. The mechanism of forming these morphologies was proposed to be adjusted by the pH value during polymerization. Ultraviolet–visible (UV–vis) absorption spectra and Raman spectra suggested that these as-prepared PANI were in conductive emeraldine state and featured obviously different molecular structures, which aroused from different reaction conditions.