Exploring the corrosion resistance of epoxy coated steel by integrating mechanochemical synthesized 2D covalent organic framework.

[Display omitted] • The 2D−COF of TpPa-1 is synthesized through mechanochemical grinding method. • The TpPa-1 can be well dispersed in the EP coatings. • The EP/TpPa-1 composite coating has superior anticorrosion performance. • The anticorrosion mechanism of the composite coating is unraveled. Organic anticorrosion coatings reinforced by 2D nanomaterials are attracting ever-increasing research interests due to their superior anticorrosion performances. However, the strong π-π and van der Waals (vdW) interactions make the conventional 2D nanomaterials difficult to realize homogenous dispersion in the coatings during coating preparation. To remedy this problem, in this work, we introduced 2D covalent organic framework (2D−COF) in epoxy resin (EP) to synergistically realize high dispersion and improve the corrosion resistance of EP coated steel, where the 2D−COF (TpPa-1) was mechanochemically synthesized from 1,3,5-triformylphloroglucinol (Tp) and p-phenylenediamine (Pa-1). The results show that the TpPa-1 can achieve self-dispersion in EP. Further analyses reveal that the self-dispersion of TpPa-1 in EP stems from the reactions between the amino groups in TpPa-1 and epoxy groups in EP. Moreover, the prepared EP/TpPa-1 composite coating coated steel presents superior corrosion resistace compared with pure EP coating due to the good dispersion of TpPa-1. The superior anticorrosion mechanism of the coated steel is unraveled by combining experiments and molecular dynamics simulations. The results show that the added TpPa-1 can effectively improve the compactness of the composite coating. This will on one hand lead to the lower diffusion rate of corrosive media, and on the other hand, enhance the adhesion strength between the composite coating and substrate. This work can trigger further studies to perform reasonable design of 2D−COF, and therefore, new anticorrosion coatings with superior physical-mechanical properties can be obtained. [ABSTRACT FROM AUTHOR]