A double-layer coating composed of an inner polyaniline (PANI) and outer epoxy layer, was investigated as a potential “smart” coating for corrosion protection of carbon steel (CS) in an aqueous 3.5 wt% NaCl. The PANI coating, incorporating an anion of sodium caprylate (SC) and sodium dodecyl sulfonate (SDS), was electrochemically synthesized directly on the CS surface. A layer of commercial epoxy was then applied on top of this PANI coating. It was determined that the SC-SDS-doped coating was able to almost completely recover its anti-corrosive properties, within one day upon creating the CS-surface-reaching damage (scratch) in it, sustaining the high level of corrosion protection for the remaining 29 days of constant exposure to the corrosive solution. On the other hand, the anti-corrosive properties of the damaged undoped coating deteriorated very quickly (within hours) and continued to deteriorate with time. The mechanism of “smart” protection of the doped coating was postulated to be through the release of the dopant (SC-SDS) from the PANI layer at the damaged coating site, driven by a potential difference between the reducing PANI layer and oxidizing (corroding) CS surface. This was followed by the adsorption of SC-SDS on the CS surface exposed to the electrolyte and its protection through the formation of a molecular SC-SDS layer offering a barrier for transport of corrosive species to the CS surface.

研究了由内聚苯胺 (PANI) 和外环氧树脂层组成的双层涂层，作为在 3.5 wt% NaCl 水溶液中用于碳钢 (CS) 腐蚀保护的潜在“智能”涂层。结合辛酸钠（SC）和十二烷基磺酸钠（SDS）的阴离子的PANI涂层直接在CS表面上电化学合成。然后在该聚苯胺涂层的顶部涂上一层商业环氧树脂。经测定，SC-SDS 掺杂涂层能够在一天内几乎完全恢复其防腐性能，在其中产生 CS 表面到达损伤（划痕）后，维持了高水平的腐蚀保护剩下的 29 天持续暴露在腐蚀性溶液中。另一方面，损坏的未掺杂涂层的抗腐蚀性能非常迅速地恶化（几小时内），并且随着时间的推移继续恶化。掺杂涂层的“智能”保护机制被假设是通过在受损涂层位置从 PANI 层释放掺杂剂 (SC-SDS)，这是由还原性 PANI 层和氧化（腐蚀）层之间的电位差驱动的。 ) CS 表面。随后是 SC-SDS 在暴露于电解质的 CS 表面上的吸附，并通过形成分子 SC-SDS 层对其进行保护，从而为腐蚀性物质向 CS 表面的传输提供屏障。掺杂涂层的“智能”保护机制被假设是通过在受损涂层位置从 PANI 层释放掺杂剂 (SC-SDS)，这是由还原性 PANI 层和氧化（腐蚀）层之间的电位差驱动的。 ) CS 表面。随后是 SC-SDS 在暴露于电解质的 CS 表面上的吸附，并通过形成分子 SC-SDS 层对其进行保护，从而为腐蚀性物质向 CS 表面的传输提供屏障。掺杂涂层的“智能”保护机制被假设是通过在受损涂层位置从 PANI 层释放掺杂剂 (SC-SDS)，这是由还原性 PANI 层和氧化（腐蚀）层之间的电位差驱动的。 ) CS 表面。随后是 SC-SDS 在暴露于电解质的 CS 表面上的吸附，并通过形成分子 SC-SDS 层对其进行保护，从而为腐蚀性物质向 CS 表面的传输提供屏障。