Accumulation of 2-Acetylamino-5-mercapto-1,3,4-thiadiazole in chitosan coatings for improved anticorrosive effect on zinc

[Display omitted] •Zn substrates were coated with thin layers of chitosan.•2-Acetylamino-5-mercapto-1,3,4-thiadiazole (AcAMT) was accumulated in the coating.•Anticorrosive protection efficiency of the system was verified by multiple methods.•The Chit-AcAMT coating provides good protection with >90% inhibition efficiency.•Chit-AcAMT is an eco-friendly, low cost choice in the temporary protection of Zn. Chitosan (Chit) coatings were applied on zinc substrates by the dip-coating method. Subsequently, the coatings were impregnated with a corrosion inhibitor, 2-Acetylamino-5-mercapto-1,3,4-thiadiazole (AcAMT) to obtain an increased anticorrosive effect. The coating thickness and the AcAMT accumulation were determined using UV–Vis spectroscopy on glass and quartz substrates, respectively. The surface morphology and coverage were investigated with atomic force microscopy. Electrochemical impedance spectroscopy and potentiodynamic polarization techniques were used to investigate the protective properties of the impregnated coatings. The chitosan coatings facilitated the accumulation of the corrosion inhibitor inside the polymeric matrix (a multiplication of 380 times compared to the impregnating solution concentration was calculated), channeling high amounts of AcAMT to the Zn surface, which resulted in an inhibition efficiency of >90%. This effect demonstrates the applicability of chitosan coatings as carriers for corrosion inhibitors, significantly reducing the amount of inhibitor needed to achieve good anticorrosive effects.