Gum Arabic-Assisted Polyaniline Nanofillers for Improving Anticorrosion Performance of Waterborne Epoxy Coatings

Abstract

The agglomeration of polyaniline (PANI) nanofillers in waterborne resins substantially reduces the long-term corrosion resistance of the resins. In this study, we use gum arabic (GA), a biological macromolecule, as a green stabilizer to prepare aqueous dispersions of GA−PANI nanofillers via chemical oxidative polymerization. The highly dispersed GA−PANI nanofillers are incorporated into waterborne epoxy (WEP) matrix and sprayed onto Q235 steel surface. The results show that the GA− PANI nanofillers exhibit excellent dispersion, stability, and compatibility in WEP, as evidenced through transmission electron microscopy and scanning electron microscopy of the crosssectional morphology, water-absorption tests, and coating adhesion tests. An electrochemical test indicates that the 3.0 wt % GA− PANI/WEP coating displays remarkable corrosion resistance, with the value of impedance modulus in the low-frequency region (| Z| 0.01Hz ) remaining at 3.372 × 10 7 Ω cm 2 after 60 days of immersion in a 3.5 wt % NaCl solution. This value is almost 1 order of magnitude higher than that of WEP. An X-ray photoelectron spectroscopy test confirms the presence of a corrosion product component on the coating/steel interface. Moreover, the GA−PANI nanofillers extend the penetration route of corrosive species and provide favorable adhesion and anodic protection.

Sulfide-Ion-Responsive Mesoporous Silica/ZIF-8 Nanocapsules to Inhibit Microbiologically Influenced Corrosion

“…As we know, BTA is an effective corrosion inhibitor for Fe-based metals, which will chelate with Fe 2+ /Fe 3+ through their lone pair of N and/or the π bonding, the formed protective layer adsorbs on the metal surface . Consequently, the penetration of the chloride ions is blocked and, therefore, reduces the formation of the corrosion products …”

“…38 Consequently, the penetration of the chloride ions is blocked and, therefore, reduces the formation of the corrosion products. 39 In addition, the corrosion rate and inhibition efficiency are calculated according to the weight loss data. As shown in Table 1, the corrosion rate of the Q235 steel substrate decreases with the increased concentration of BTA-HMSN/ZIF-8-MNZ nanocapsules, which is due to the improved surface coverage of the inhibitor molecules, 40 improving the physical barrier against the corrosive species.…”

Superhydrophobic Polyaniline–Siloxane Coatings with Excellent Barrier and Active Corrosion Protection Properties for Mild Steel

“…This triggers the transfer of stored positive charge from the oxidized form of PANI (emeraldine salt) to the defect site to form a passive metal oxide layer that prevents further corrosion. 23 Inorganic acids are the most used protonic acids for doping PANI. 21,24,25 Unfortunately, the poor dispersion in the solvents caused by the stiff moiety of these inorganic acid-doped PANIs limits their use in coatings.…”

“…Subsequently, Fe will be oxidized, and electrons will be released. This triggers the transfer of stored positive charge from the oxidized form of PANI (emeraldine salt) to the defect site to form a passive metal oxide layer that prevents further corrosion …”

Recent progress of self-healing polyaniline organic composite coatings: active agents, methods and protection mechanism

“…This results in improved adhesion, an active protection effect and self-healing abilities based on dopants. However, it is challenging for PANI to fully dissolve or disperse within organic coatings because of their rigid nature and large molecular weight (up to tens or hundreds of thousands), causing aggregation defects in coatings and a reduction of longterm corrosion resistance (Shao et al, 2023). Additionally, the passivation ability of PANI (EB) and doped PANI is limited because of PANI's relatively fixed redox potential.…”