Preparation of bromo‐substituted polyaniline with excellent antibacterial activity

Abstract

Bromo-substituted polyaniline (Br-PANI) is prepared by a novel strategy in which PANI is used as raw material, potassium bromate and potassium bromide as brominate regents. The obtained Br-PANI is characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, elemental analysis, FTIR, UV-vis spectra, and TGA. The results clearly indicate that Br has successfully attached to the benzene ring of PANI by chemical bond. The behavior of Br-PANI toward bacteria is characterized by plate counting, minimal inhibitory concentration, and minimal bactericidal concentration methods. The experimental results indicate that both doped and dedoped Br-PANIs have long-term antibacterial activities as compared to doped/dedoped PANI. What's more, the antibacterial abilities increase with increasing the Br/N molar ratio of the Br-PANI. Thus Br-PANI should be a kind of efficient and environmentally friendly antibacterial agent.

Effect of structural factors on the physicochemical properties of functionalized polyanilines

“…47,48,67,78 PANI derivatives with electron-withdrawing substituents also exhibit a bathochromic and hypsochromic shi of absorption maxima. 27,84,97 Halo derivatives of PANI have an absorption maximum with a bathochromic shi with respect to PANI that is due to the presence of an electron-withdrawing halogen substituent that decreases the delocalization of the electric charge in the conjugated polymer system (Fig. 12).…”

“…It was noted that the hypsochromic shi increases with an increase in the bromine content in functionalized PANI. 27 The absorption maxima of poly-ortho-phenylenediamine are shied relative to those of PANI towards shorter wavelengths due to the steric effect of the functional group. 85,109,110 The hypsochromic shi of the maxima in the spectra of poly-metaaminophenol and poly-ortho-phenylenediamine, despite the strong electron-donating effect, occurs because they exist in the form of a ladder-type structure, which decreases the degree of conjugation of the polymer chain, similarly to the majority of PANI derivatives.…”

“…Due to the large atomic radius of bromine, which increases the twisting and decreases the conjugation in the macromolecular chain in the series of PANI halogen derivatives, the heat resistance of poly-ortho-bromaniline is the smallest. 27,137 It was found that PANI halogen derivatives have lower stability than alkylated derivatives, for example, poly-orthotoluidine. 123 As shown by thermogravimetric analysis, incorporation of a hydrophilic group in the macromolecular chain decreases the thermal stability of functionalized PANI in comparison with the unsubstituted polymer.…”

“…Bromine, both in ionic state and in compounds with covalent bonds, is known to have pronounced bactericidal properties. 27,179 Therefore, its incorporation in the PANI macromolecular chain is promising in terms of producing a component for antimicrobial coatings. It is also important that, unlike conventional antibacterial agents, brominated PANI has both an anti-fouling property and an excellent anticorrosion effect.…”

“…Nevertheless, several attempts were made to incorporate substituents into the aromatic ring in the PANI macromolecular chain. 20,21,27 It should be understood in this case that upon incomplete conversion of the starting compound, polymers with varying chain lengths, irregular structures and unsatisfactory target properties are very likely to be obtained.…”