Mimosa inspired intelligent anti-corrosive composite coating by incorporating lignin and pyridine derivatives grafted graphene oxide

Although the coating can effectively prevent metal corrosion, it is easy to form micro-pores and micro-cracks during the curing process, and the coating is inevitably damaged by the external environment during use, resulting in a reduction in its protective ability, thereby shortening the service life of the substrate. Inspired by the stress closure function of mimosa, an intelligent anti-corrosion coating with stress closure function against corrosion products (Fe2+) was prepared by using pyridine derivatives and lignin grafted graphene oxide (ATGO). By density functional theory calculation, the binding energy of pyridine group and Fe2+ was −369.99 kcal/mol, and their strong complexation would facilitate the formation of a dense protective layer at the metal corrosion interface. The test results showed that ATGO-CM coating had high fracture strength (86.9 MPa) and adhesion strength (2.03 MPa), as well as low water vapor permeability (1.3 × 10-6 g m−1 day−1 Pa−1). Electrochemical testing denoted that after soaking in 3.5 wt% saline solution for 100 days, the impedance modulus of the ATGO-CM coating remained at 5.36 × 109 Ω·cm2 at low frequencies (f = 0.01 Hz), which was two orders of magnitude higher than the blank group. Through scratch experiments showed that the complexation effect of pyridine groups and corrosive products could significantly improve the corrosion resistance of the coating, with Rct value of 1.8 × 104 Ω cm2 for the damaged coating, one order of magnitude higher than the blank group. This work not only provided a reference for the preparation of intelligent anti-corrosion coatings with bionic functions, but also increased the added value of biomass materials.