Ultrafast and high-efficient self-healing epoxy coatings with active multiple hydrogen bonds for corrosion protection

Combining a fast self-healing action and a high barrier property remains a challenge in polymeric protective coatings. Herein, we report an intrinsic self-healing epoxy coating in which 2-ureido-4[1H]-pyrimidinone (UPy) as a quadruple hydrogen bonding unit, grafted onto the backbones of an epoxy-matrix by an amine-terminated oligo(propylene glycol) linker. Without any intervention, the epoxy-matrix performs its self-healing function in ∼5 min, even under aqueous immersion. Besides, electrochemical impedance spectroscopy measurements demonstrate corrosion protection ability of such self-healed coating on a steel substrate, with a high |Z|0.01Hz value of 4.8 × 1010 Ω·cm2 after 60 days of immersion in NaCl solution.