Halloysite@Polyaniline Nanoparticles Loaded with the Praseodymium (III) Cation for Improving Active Corrosion Protection of Waterborne Epoxy Coating

Abstract

The corrosion resistance of the waterborne epoxy coating is poor during long-term service, which greatly limits its widespread application. In this paper, the halloysite nanotubes (HNTs) were modified by polyaniline (PANI) and then used as nanocontainers to encapsulate the green corrosion inhibitor praseodymium (III) cations (Pr 3+ ), obtaining HNTs@PANI@Pr 3+ nanoparticles. A scanning electron microscope, transmission electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis were applied to characterize the formation of PANI and the absorption of Pr 3+ cations. The corrosion-inhibiting ability of the HNTs@PANI@Pr 3+ nanoparticles for iron sheets and the anticorrosion properties of the nanocomposite coatings were evaluated by the electrochemical impedance spectroscopy technique. The results indicated that the coating containing HNTs@ PANI@Pr 3+ nanoparticles exhibited excellent anticorrosion performance. After immersion in 3.5 wt % NaCl solution for 50 days, its Z f=0.01 Hz value was still as high as 9.4 × 10 8 Ω cm 2 . The i corr value was 3 orders of magnitude lower than that of the pure WEP coating. The excellent anticorrosion property of the HNTs@PANI@Pr 3+ coating could be attributed to the synergy of three beneficial factors, including evenly distributed nanoparticles, PANI, and Pr 3+ cations. This research will provide theoretical and technical support for the development of waterborne coatings with high corrosion resistance.

Adhesion-Diffusional-Based Corrosion Protection Mechanisms of Polyaniline-Primed Fluoropolymer Coatings

“…This electrochemical approach not only enhances surface adhesion but also allows for the inclusion of a corrosion-mitigating layer, making it a promising technique for achieving higher coating integrity and overall corrosion protection. , Polyaniline (PANI) and its derivatives are one of the most sought-after conductive polymers owing to their exceptional blend of high electrical conductivity, superior environmental stability, tunability, good processability, diverse synthesis methods, and cost-effectiveness . Recent studies have explored the incorporation of PANI into protective coatings to harness its unique properties for corrosion protection. ,− For instance, Tallman et al demonstrated the capacity of PANI to protect against corrosion through its catalytic capability of forming a passivating oxide layer . Although PANI manifests in various forms contingent on its oxidation level, emeraldine base (EB), its half-oxidized state, can undergo doping or protonation to yield the emeraldine salt (ES) form, recognized as the most conductive PANI state .…”

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

“…They are capable of absorbing inhibitors within their interior pores. Similar to GO, aniline undergoes in situ polymerization on hydroxides, carboxyl groups and within the interior pores of CNTs and HNTs (Tang et al, 2023;Najmi et al, 2021;Jalali et al, 2023).…”

“…Praseodymium (III) effectively modified PANI and achieved organic coatings with active protection performance. Tang et al (2023) concluded that the PANI waterborne epoxy coatings containing Pr 31 cationic corrosion inhibitor modified PANI, resulting in outstanding corrosion resistance with an i corr three orders of magnitude lower than that of the pure waterborne epoxy coatings. According to Samiee et al (2020), the coatings' highest corrosion protection resulted from the GO-PANIs modification with Pr 31 cations.…”