In situ pretreatment and self-healing smart anti-corrosion coating prepared through eco-friendly water-base epoxy resin combined with non-toxic chelating agents decorated biomass porous carbon

The aim of this work is to develop one eco-friendly smart anti-corrosion coating with in situ pretreatment and self-healing characteristics to reduce the environmental pollution and simplify operations of traditional coating. Herein, porous carbon nanosheets (PCNS) derived from fallen leaves were prepared through exfoliating the biomass into nanosheets with acetic acid and drilling holes through carbonization and activation via ZnCl2. The as-fabricated PCNS contained meso- and micro-pores, ultra-thin layer structure (the thickness of around 5 nm) and rich oxygen-containing functional groups. Also, the specific surface area was 1262 m2 g−1. The smart coating was prepared through doping the functional PCNS (FPCNS) which prepared by loading pyhtic acid (PA) in the holes and grafting aminopropyltriethoxysilane (APTES) onto the PCNS surface into the eco-friendly water-base epoxy resin. The pull-out tests demonstrated that adhesion between steel and coating was increased from 3.0 MPa to 6.4 MPa due to the addition of FPCNS into the coating. Results of electrochemical impedance spectroscopy indicated that the/Z/f=0.01Hz of smart coating maintained 1.30 × 107 Ω cm2 after 50 days immersion and/Z/f=0.01Hz of cracked smart coating was 15,000 Ω cm2 after 28 days of immersion. The reasons of the excellent adhesion and anti-corrosion performances of smart coating were: (1) the grafted APTES could adsorb on steel surface to form a pretreatment layer; (2) the loaded PA could chelate the corrosion products to repair the cracks. It is expected that the smart coating could find wide application in anti-corrosion coating field due to the in situ pretreatment and self-healing characteristics.