The economic impact of metallic corrosion on global infrastructure, spanning pipeline networks, bridges, refineries, and automobiles, is considerable. In 2013, it accounted for 3.4% of the global GDP, totaling US$ 2.5 trillion. Organic coatings have gained significance as a prominent strategy to address this widespread issue. Polyaniline (PANI), a conducting polymer, has long been recognized as an effective anti-corrosion coating. This study explores the potential of polyaniline analogs and their nanocomposites as candidates for protective organic coatings in corrosion control applications. Initially, the investigation focuses on conducting polymers with side chains comprising long, branched alkyl groups as potential corrosion suppression coatings. These polymers, containing carbazole, phenothiazine, and phenoxazine cores, serve as analogs to polyaniline. Prepared through the Buchwald/Hartwig coupling reaction, these polymers demonstrated promising corrosion suppression capabilities, as tested by potentiodynamic polarization studies and electrochemical impedance spectroscopy (EIS). Morphological characterization using scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that phenothiazine- and carbazole-containing polymers exhibit excellent corrosion resistance, with phenothiazine displaying a protection efficiency (PE) of 95.9% and 89.0% respectively, outperforming polyaniline coating. Further exploration involved the derivatives of phenothiazine-based PANI analogs, specifically poly(heterocyclic diphenylamine) (poly-HDA), prepared through the Buchwald/Hartwig coupling reaction. Evaluation through weight loss, potentiodynamic polarization, and EIS in a 3.5 wt.% NaCl solution showcased the reduced corrosion current density on surfaces coated with long-branched alkyl-substituted phenothiazine-based PANI analogs. Moreover, the reinforcement of the phenothiazine-based PANI analog polymer was achieved by creating an epoxy-based nanocomposite with 2,5-dimethyl-1,4-phenylenediamine functionalized graphene oxide (PT/DPPD-fGO) at varying concentrations into an epoxy anticorrosive coating for AISI 4130 steel from corrosion. Results from immersion in 5 % sodium chloride solution, coupled with standard electrochemical measurements, demonstrate that PT/DPPD-fGO effectively protects AISI 4130 steel from corrosion, with coatings containing 5 % PT/DPPD-fGO exhibiting the best corrosion performance among the tested specimens. The results indicate the potential of phenothiazine- and carbazole-based PANI analogs, along with their nanocomposites, as candidates for protective organic coatings in transportation, aviation, marine, and oil and gas industrial applications.
| Identifer | oai:union.ndltd.org:MSSTATE/oai:scholarsjunction.msstate.edu:td-7326 |
| Date | 13 August 2024 |
| Creators | Awoyemi, Raymond Femi |
| Publisher | Scholars Junction |
| Source Sets | Mississippi State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
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