Influences of Single and Dual Anticorrosion Agent Usage on Growth and Corrosion Protection of the <scp>LbL</scp> Multilayered Coatings

ABSTRACT The aim of this article is to prepare and characterize anticorrosive polyelectrolyte multilayers (PEMs) including benzotriazole (BTA) and/or imidazolium‐based ionic liquids (IL) as inhibitors using the Quartz Crystal Microbalance‐Dissipation (QCM‐D). Here, we demonstrate a different strategy for the development of corrosion inhibitor containing PEMs based on poly (allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) on AA2024 aluminum alloy. For this purpose, the inhibitors are deposited into/onto PEMs with the cationic polyelectrolyte (PE) solely or in combination during the multilayer growth. UV–Vis analyses confirm the presence of inhibitors in (PAH.BTA‐PAA) 5 , (PAH.IL 0.8 ‐PAA) 5 , and (PAH.IL.BTA‐PAA) 5 . SEM analysis showed the existence of LbL coatings on AA2024 even after 3.5% NaCl exposure. Electrochemical analyses show that the corrosion protection performances of the coatings are as follows: (PAH.IL.BTA‐PAA) 50 &gt; (PAH.BTA‐PAA) 50 &gt; (PAH.IL 0.8 ‐PAA) 50 &gt; AA2024. The bare AA2024 shows the highest corrosion tendency with a corrosion potential (E corr ) of −0.77 V and a corrosion current density ( I corr ) of 30.7 μA/cm 2 whereas (PAH.IL.BTA‐PAA) 50 has the most positive corrosion potential at −0.72 V and the lowest corrosion current density at 4.17 μA/cm 2 , indicating approximately 10 times better corrosion resistance. Furthermore, (PAH.IL.BTA‐PAA) 50 exhibits the lowest rate at 0.009 mm/year while pristine AA2024 has the highest rate at 0.091 mm/year. Inhibition efficiencies of (PAH.BTA‐PAA) 5 , (PAH.IL 0,8 ‐PAA) 5 , and (PAH.IL.BTA‐PAA) 5 are found to be 70.5%, 67.8%, and 86.4%, respectively. The superior corrosion protection of the PEM including IL‐BTA mixture can be attributed to its synergistic effect. Nanostructured Layer by Layer (LbL) coatings including dual agent may provide new opportunities for greater corrosion protection.