Construction of hierarchical nanocarrier via a “MOFs plus graphene” strategy for sustained release and rust-induced self-healing

Abstract

The fact that conventional self-healing coating is susceptible to the leakage of self-healing agents and investigated so far to mostly cope with the corrosion resulted from the mechanical damage of coating as a function of complex internal/external stimuli motivates researchers to fucus on the application of innovative materials on the coating system. Herein, a gallic acid-loaded hierarchical nanocarrier (UiO-66-NH2@rGO) combined porous UiO-66-NH2 (Zr6O4(OH)4(bdc-NH2)6; bdc-NH2 = 2-amino-1,4-benzenedicarboxylate) (UiO-Universitetet i Oslo) frameworks with reduce graphene oxide (rGO), and was engineered to assist the self-healing at defined target sites beneath the lossless coating. With the prominent stability, abundant encapsulation and straightforward sustained release, this hierarchical structure contributes to preventing leakage of guests suffered from the structure damage and simplify the response factor of self-healing effect. Besides, the self-healing on mild steel is induced by the formation of rust layer and firstly introduced for the inhibition of local coating delamination and corrosion activity – that is, an additional metal-phenolic passivating film deposited via the continuous etching and assembly with Fe (III) from rust layers. This work contributes to the focus of researchers on the frameworks or hierarchical material in the field of self-healing material and molecule delivery while also providing a novel strategy of target healing to the long-term corrosion inhibition of lossless coating.