Exploitation of natural gum exudates as green fillers in self-healing corrosion-resistant epoxy coatings

Recently, interest in developing green polymer coatings which provide self-healing and corrosion protection functions using bio-based renewable materials has significantly increased. In this study, microcapsules containing biopolymers from cashew gum and gum Arabic have been prepared by interfacial polymerization. The prepared microcapsules were individually and combinatorially embedded into epoxy coatings and the resulting composite coatings were then applied on Q235 steel substrates. The performance of the composite coatings was evaluated by immersing both scribed and unscribed coatings in simulated seawater. Surface analytical (SEM), physico-chemical (FTIR, XRD, XPS), and electrochemical impedance spectroscopy (EIS) techniques were used to investigate self-healing and corrosion resistance effectiveness of the polymer composite coatings. The obtained results revealed that cashew gum and gum Arabic could heal the scribed coating surface and subsequently suppressed corrosion reaction, without the aid of any catalyst or co-reactant. The performance was observed to be higher when the two gum exudates were combined. Thus, cashew gum and gum Arabic have demonstrated that they possess properties required for potential utilization in the formulation of marine anticorrosion and self-healing epoxy coatings.