سننتز و مشخصه يابي پلي دوپامين/ پلي‌آنيلين / نانولوله چندجداره كربني: عامل ضد خوردگي حساس به pH با كارايي بالا

Fabrication an‎d eva‎luation of anti-corrosion properties of epoxy/modified multi-walled carbon nanotube coating

شيمي پليمر

In this study, for the first time, a pH-responsive san‎dwich-like nanostructure with excellent anticorrosion potential was developed an‎d incorporated into an epoxy coating. Initially, multi-walled carbon nanotubes (MCs) were oxidized, an‎d chemical polymerization of aniline was carried out in the presence of 8-hydroxyquinoline-5-sulfonic acid (HQSA) as a dopant, forming the first polymeric layer on the oxidized MCs (OMC). Subsequently, dopamine was polymerized in the presence of OMC/PANI-HQS-, resulting in the formation of a san‎dwich structure (OMC/PANI-HQS-/PDA), composed of an MC core, a middle PANI-HQS- layer, an‎d an outer polydopamine shell. The synthesized nanostructure an‎d its intermediates were incorporated into epoxy resin an‎d thoroughly investigated. The chemical structure an‎d surface morphology of OMC, OMC/PANI-HQS-, an‎d OMC/PANI-HQS-/PDA were characterized using FT-IR, XRD, TEM, an‎d FESEM analyses. Mechanical properties of the coatings were eva‎luated through tensile testing, while the controlled release behavior of the HQSA inhibitor from OMC/PANI-HQS-/PDA nanocarriers was monitored by UV-Vis spectroscopy. The corrosion protection performance of the coatings containing different nanostructures was examined via electrochemical impedance spectroscopy (EIS) an‎d potentiodynamic polarization (PDP) measurements. The results demonstrated that incorporation of only 0.5 wt% of the san‎dwich-like OMC/PANI-HQS-/PDA nanostructure into epoxy resin led to a significant enhancement—by more than three orders of magnitude—in corrosion resistance (as evidenced by the reduction of corrosion rate from 2.07×10−2 to 8.44×10−6 mm/year). Furthermore, the addition of this nanocarrier resulted in an approximate 100% reduction in coating porosity. EIS analysis revealed that the coating containing 0.5 wt% of the nanocarrier exhibited a much higher impedance value (1.38×109Ω•cm²) after 10 days of immersion, compared to the neat epoxy coating (4.05×106 Ω•cm²).This superior performance was attributed to enhanced ionic barrier resistance, improved charge-transfer inhibition, strong interfacial bonding between the modified nanotubes an‎d the polymer matrix, uniform dispersion, an‎d effective corrosion inhibition. Additionally, EDX analysis an‎d release studies confirmed the release of HQSA from the nanocarrier, along with the formation of a compact passive Fe₂O₃/Fe₃O₄ layer on the steel surface,

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