resumo
Driven by the recent discovery of tannic acid (TA) as an effective green corrosion inhibitor for AA2024 alloy, this study evaluates its suitability as an additive for epoxy (EP) and polyurethane (PU) coatings, both through direct addition and by immobilization into layered double hydroxides (LDH-TA). LDH-TA was characterized by XRD, FTIR, and UV-visible spectrophotometry. Also, its anticorrosion performance was evaluated using EIS. The results show that the direct addition of TA to EP and PU coatings reduces their barrier properties, whereas incorporating LDH-TA into the polyurethane matrix provides superior corrosion protection compared to the epoxy coating. Therefore, LDH-TA-loaded PU coating (PU-LDH-TA) was further characterized through rheology analysis, surface characterization, release studies, and electrochemical techniques (EIS and SVET). The findings indicate that after 28 days, |Z| at 10-2 Hz for PU-LDH-TA remains over one order of magnitude higher than PU. Besides, upon coating defects, tannate anions released from the polyurethane coating form a protective Al/tannate-rich hydroxide layer at the defect site. Thus, PU-LDH-TA demonstrates effective active corrosion protection in saline media while maintaining the structural integrity of the coating.
palavras-chave
LAYERED DOUBLE HYDROXIDES; WATER; LDH; MG
categoria
Chemistry; Materials Science; Physics
autores
del Olmo, R; Neves, C; Bastos, A; Arrabal, R; Tedim, J
nossos autores
António Alexandre Cunha Bastos
Investigador Auxiliar
Cristina Sofia dos Santos Neves
Investigador Júnior
João Tedim
Professor associadoProjectos
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
This work was developed within the scope of Project CICECO-Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020, and LA/P/0006/2020) , financed by national funds through the FCT/MEC (PIDDAC) . R. del Olmo acknowledges the financial support from the Margarita Salas CT18/22 postdoctoral grant. A. Bastos and C. Neves are funded by national funds (OE) , through FCT-Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. R. Arrabal acknowledges the support by PID2021-124341OB-C22/AEI/10.13039/501100011033/FEDER, UE (MICIU) .