Tetraaniline-modified Co-MOF-PDA for anti-corrosive reinforcement of waterborne epoxy coating

Abstract

The main aim of this study was to exploit the advantages of dopamine and tetraaniline (TA) to enhance the physical barrier properties and active anti-corrosion performance of composite coatings; in this study, the growth of polydopamine on the surface of Co-MOF enhanced its compatibility with waterborne epoxy, and Co-MOF-PDA-TA (MP-TA) was successfully synthesised by adding dopamine and tetraaniline via Michael addition, confirmed through characterisation methods such as Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. MP-TA can be added as a nanofiller additive to water-based epoxy coatings, and a detailed study on the corrosion resistance of the prepared composite coatings showed that the composite coating containing 0.50wt% MP-TA/WEC exhibits good anti-corrosion performance with an impedance modulus at low frequency (0.01 Hz) of 7.253 × 109 Ω cm2 because TA not only prolongs the time required for corrosion ions to reach the interface but also forms a passivation film on the steel surface. Moreover, the reduced TA can be oxidised to EB or even LEB by releasing two electrons, which further promotes the formation of a passivation film, providing a good pathway for the application of MP-TA as a multifunctional additive.