pH-Sensitive Polydopamine–La (III) Complex Decorated on Carbon Nanofiber toward On-Demand Release Functioning of Epoxy Anti-Corrosion Coating

Abstract

The high aspect ratio and unique thermal and electrical characteristics of carbon nanofiber (CNF) made it an ideal physical barrier against the penetration of corrosive ions. However, the poor compatibility of the CNF with the polymer matrix and the lack of active corrosion inhibitors are the key limitations of this nanomaterial, resulting in short-term anti-corrosion resistance. An intelligent self-healing epoxy (EP) coating, including CNF modified with a polydopamine (PDA)−La 3+ complex, was successfully fabricated to overcome these issues. Electrochemical impedance spectroscopy (EIS) evaluation implied that mild steel (MS) submerged in a 3.5 wt % NaCl solution containing the CNF− PDA−La extract had a total corrosion resistance (R T ) of 3107 Ω cm 2 after 24 h, which is much greater than the MS immersed in the blank solution (1378 Ω cm 2 ). Furthermore, the potentiodynamic polarization analysis indicated a 50% reduction in the corrosion rate (CR) of the MS soaked in the solution containing released PDA and La 3+ inhibitors compared to the blank solution. EIS and salt spray analysis were used to assess the self-healing capabilities of epoxy coatings incorporating modified CNFs. EIS assessment of scratched coatings revealed a 117% improvement in R T of the CNF−PDA−La/EP coating compared to the Blank/EP after 10 h of immersion in the saline solution. This enhancement is due to the intelligent release of PDA and La 3+ inhibitors at the scratch sites, which can mitigate MS corrosion by forming a PDA−Fe complex and the deposition of La(OH) 3 on the MS surface. The salt spray test results also exhibited the CNF−PDA−La/EP coating's superior anti-corrosion capabilities after 20 days. Hence, this research presents a logical approach for developing anti-corrosion coatings with improved nanofiller compatibility and self-healing characteristics.

Improved Interfacial Interactions of Dip Coatings by In Situ Introducing Silica to Enhance Corrosion Resistance and Metal Bonding Strength

“…A notable feature of epoxy resins is their excellent adhesion properties. Nanoparticles can be firmly adhered to the interior of the epoxy resins by introducing nanotechnology into epoxy-based coatings, resulting in various types of resin matrix nanocoatings. − Ordinarily, nonuniform nanoparticles doped within resin matrix coatings have a high potential to cause poor corrosion resistance in the resultant coatings. On the other hand, the interfacial air retention after nanoparticle doping may allow the resultant coating to experience osmotic pressure when in corrosive medium, thereby resulting in a reduction in corrosion resistance.…”

“…However, the impedance modulus of pure epoxy coatings is 6 orders of magnitude higher. − In this case, researchers have concentrated their efforts on the development of epoxy-based coatings with nanoparticle doping to further improve the anticorrosion properties. To date, graphene, carbon nanotubes or nanofibers, polyaniline, MOF, and MXene have been doped into epoxy resins to enhance the corrosion resistance of the resultant coatings. The impedance modulus of coatings made using resin matrix nanocomposites barely exceeds 10 9 Ω·cm 2 , particularly when using a one-step dip coating method.…”

Eco-Friendly Fumed Nanosilica@Nanodiamond Hybrid Nanoparticles with Dual Sustainable Self-Healing and Barrier Anticorrosive Performances in Epoxy Coating

“…Carbon nanomaterials, such as carbon nanotubes, 18,19 carbon nanofibers, 20,21 carbon nanospheres, 22,23 and graphene oxide (GO), 24,25 have been examined extensively in the field of corrosion protection. Nanodiamond (ND) is another carbonbased nanomaterial possessing many interesting properties such as high mechanical properties, good electrical insulating properties, high hardness, tunable surface chemistry, inert chemical characteristics, nontoxicity, and biocompatibility.…”

“…Carbon nanomaterials, such as carbon nanotubes, , carbon nanofibers, , carbon nanospheres, , and graphene oxide (GO), , have been examined extensively in the field of corrosion protection. Nanodiamond (ND) is another carbon-based nanomaterial possessing many interesting properties such as high mechanical properties, good electrical insulating properties, high hardness, tunable surface chemistry, inert chemical characteristics, nontoxicity, and biocompatibility. − Considering such interesting performances of ND, we hypothesized that the incorporation of ND with nanosilica through a wise procedure can improve the performance of nanosilica and offer hybrid nanoparticles with multifunctional properties in the field of corrosion protection.…”

Falcaria vulgaris leaves extract as an eco-friendly corrosion inhibitor for mild steel in hydrochloric acid media

“…Nowadays, metal corrosion is one of the most severe challenges confronting industries. Mild steel (MS), one of the most ubiquitous building materials, is highly susceptible to corrosive ions despite its remarkable qualities, including excellent mechanical capabilities and affordability 1 . Various methods are used to remove contaminants and rust from the MS surface, the most common of which is acid washing (especially using HCl) 2 .…”