In this study, two quaternary ammonium-based copolymers (DAC-DAD10 and DAC-DAD20) with varying hydrophilicity/hydrophobicity are synthesized, characterized, and their capacity to suppress P110 carbon steel (P110 CS) corrosion in 3.5% NaCl is examined. DAC-DAD10 and DAC-DAD20 were synthesized using diallylammonium chloride (DAC) and N1, N1-diallyl-N6-dodecyl-N6, N6-dimethylhexane-1,6-diaminium dichloride (DAD) and their inhibition potential (%IE) and mechanism were studied by different experimental and computational methods. The outcomes suggest that the %IE of DAC-DAD10 and DAC-DAD20 increases on increasing the hydrophobicity as DAC-DAD20, having a large hydrophobic alky chain, showed relatively better %IE than DAC-DAD10. DAC-DAD10 and DAC-DAD20 manifest the best %IE of 88.68% and 96.17%, respectively, at concentrations as low as 3 mgL. Potentiodynamic polarization studies indicate that they behave as cathodic-type inhibitors. Their adsorption on the metallic surface followed the Langmuir adsorption isotherm. Various surface analyses, including SEM-EDS, and XPS, confirm that they adsorb at the metal and electrolyte interface and build a corrosion protective layer. DFT study suggests that quaternary nitrogen atoms easily deprotonate and coordinate with the metallic surface using their unshared electron pairs. The corrosion inhibition based on experimental and computational analyses is schematically presented and described.

中文翻译：

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使用季铵基共聚物对适用于套管和油管应用的 P110 碳钢在 3.5% NaCl 溶液中的腐蚀抑制

在本研究中，合成并表征了两种具有不同亲水性/疏水性的季铵基共聚物（DAC-DAD10 和 DAC-DAD20），并检查了它们在 3.5% NaCl 中抑制 P110 碳钢 (P110 CS) 腐蚀的能力。使用二烯丙基氯化铵 (DAC) 和 N1, N1-二烯丙基-N6-十二烷基-N6, N6-二甲基己烷-1,6-二氯化二胺 (DAD) 合成 DAC-DAD10 和 DAC-DAD20 及其抑制潜力 (%IE) 和通过不同的实验和计算方法研究了机理。结果表明，DAC-DAD10 和 DAC-DAD20 的 %IE 随着疏水性的增加而增加，因为具有较大疏水烷基链的 DAC-DAD20 表现出比 DAC-DAD10 相对更好的 %IE。在浓度低至 3 mgL 时，DAC-DAD10 和 DAC-DAD20 的最佳 %IE 分别为 88.68% 和 96.17%。动电位极化研究表明它们表现为阴极型抑制剂。它们在金属表面的吸附遵循朗缪尔吸附等温线。各种表面分析，包括 SEM-EDS 和 XPS，证实它们吸附在金属和电解质界面上并形成腐蚀保护层。 DFT 研究表明，季氮原子很容易去质子化，并利用其不共享的电子对与金属表面配位。示意性地呈现和描述了基于实验和计算分析的腐蚀抑制。