A facile, solvent-free and scalable method to prepare poly(aniline-co-5-aminosalicylic acid) with enhanced electrochemical activity for corrosion protection

A facile and simple route has been proposed to prepare poly(aniline-co-5-aminosalicylic acid) (PAASA) nanofibers with enhanced electrochemical activity by chemical oxidative polymerization in aqueous solution. The as-prepared PAASA copolymers were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy. The microstructure, composition, morphology and properties of the copolymers were found to be dependent on the molar ratios of the monomers (5-aminosalicylic acid/aniline). The growth mechanism of the copolymer nanofibers is revealed to be the initial spherical soft-template aggregates of monomer-dopant salt followed by nanofiber chain-growth and elongation. The incorporation of 5-aminosalicylic acid into polyaniline backbone tuned the morphology of the resulting nanofibers as well as electrochemical activity from acid environment to wide pH environment ranging from acid to neutral environment, different from the behavior of polyaniline which become electrochemical inactive for pH ≥ 4. This work enable the conducting polyaniline nanofibers new application, especially in the area that high electrochemical activity in neutral environment is required. Nanocomposite coatings of the PAASA nanofibers (0.5 wt%) filled epoxy modified acrylate/amino baking paint (EMA/A) show significant electrochemical corrosion protection at neutral environment.