Microwave-functionalized natural tannic acid as an anticorrosive UV-curable coating

Corrosion causes serious steel deterioration with consequent negative impacts on the environment and economy. Organic coatings are widely exploited to provide corrosion protection on low-carbon steel. However, the raw materials and preparation methods for common anticorrosive coatings are not sustainable. In this framework, the efficient microwave-assisted methacrylation of a natural polyphenolic compound, tannic acid (TA), provided a UV-curable monomer with a high degree of substitution. The produced methacrylated tannic acid (MTA) was characterized by means of 31P NMR and FTIR spectroscopies. The UV-curing of MTA by radical photopolymerization was deeply investigated via the real-time FTIR, photo-DSC, and photo-rheological analyses, confirming the high photo-reactivity of MTA with a conversion of 80 % and a gel point at 2.5 s. The UV-cured MTA showed good thermal stability and a glass transition temperature (Tg) of 133 ◦C. Furthermore, UV-cured MTA coating exhibited high hardness and hydrophobicity. The zeta potential measurement indicated a negatively charged surface with an isoelectric point (IEP) at pH 2.7. Finally, the good corrosion protection performance of UV-cured MTA coating on plasma pre-treated steel surface was assessed through electrochemical impedance spectroscopy.

Corrosion causes serious steel deterioration with consequent negative impacts on the environment and economy. Organic coatings are widely exploited to provide corrosion protection on low-carbon steel. However, the raw materials and preparation methods for common anticorrosive coatings are not sustainable. In this framework, the efficient microwave-assisted methacrylation of a natural polyphenolic compound, tannic acid (TA), provided a UV-curable monomer with a high degree of substitution. The produced methacrylated tannic acid (MTA) was characterized by means of 31P NMR and FTIR spectroscopies. The UV-curing of MTA by radical photopolymerization was deeply investigated via the real-time FTIR, photo-DSC, and photo-rheological analyses, confirming the high photo-reactivity of MTA with a conversion of 80 % and a gel point at 2.5 s. The UV-cured MTA showed good thermal stability and a glass transition temperature (Tg) of 133 °C. Furthermore, UV-cured MTA coating exhibited high hardness and...