Dynamic hydrogen-bond inspired coating with enhanced interfacial mobility for integrated corrosion resistance and self-healing performance

The incorporation of two-dimensional fillers restricts polymer chain mobility, thereby worsening the self-healing capability of organic coatings. To address this challenge, this study is inspired by dynamic hydrogen-bond strategy, an intrinsic self-healing composite coating of flexible-chain benzoxazine-derived Schiff base-modified epoxy resin with L-histidine-functionalized graphene oxide (EBP-fGO) is successfully prepared on the Mg alloy, which simultaneously enhances corrosion resistance and self‑healing performance. The self-healing property of EBP is derived from the synergistic effect of Schiff-based bonds topological rearrangement in the polymer and imidazole groups on fGO catalyzing benzoxazine ring-opening polymerization, promoting hydrogen bond formation and enhancing interfacial chain mobility near the fillers within the polymer matrix. Furthermore, fGO incorporation enhances corrosion protection via labyrinth effects, while its hydrogen bonding with the EBP matrix ensures optimal interfacial compatibility. After 21 days of immersion in 3.5 wt.% NaCl solution, the impedance modulus of this coating decreased by less than two orders of magnitude, from 4.15×10 10 Ω·cm 2 to 6.12×10 8 Ω·cm 2 , demonstrating excellent corrosion resistance and durability. Besides, the EBP-fGO coating can achieve a self-healing efficiency of up to 92.6%, through a facile heat treatment. A unique strategy is thus proposed to enhance self-healing performance by promoting interfacial molecular mobility, offering a viable solution to reconcile the inherent conflict between enhanced barrier properties and restricted self-healing capability in two-dimensional filler-reinforced coatings for Mg alloy corrosion protection.