Smart hBN/epoxy vitrimer coating with distinct mechanisms for thermally activated self-repair and corrosion protection

Smart coatings that integrate distinct mechanisms for thermally activated self-repair and corrosion protection offer an advanced strategy to enhance the durability of metallic structures. In this study, an epoxy vitrimer matrix was modified with 2-aminophenyl disulfide (2-APD) hardener to introduce dynamic disulfide bond exchange, enabling reversible network rearrangement under heat activation. However, coatings containing only 2-APD exhibited limited corrosion resistance due to insufficient barrier performance. To address this limitation, hexagonal boron nitride (hBN) was incorporated at varying concentrations (0.5–1.5 wt%) as a multifunctional nanofiller to reinforce the barrier layer and support heat distribution during the repair process. The EP/APD–1 hBN coating achieved the highest self-repair efficiency of 88% and exhibited improved hydrophobicity and corrosion resistance in 3.5 wt% NaCl solution. The corrosion rate decreased by 94%, from 8.79 × 10−4 to 0.50 × 10−4 mm/yr, compared to the epoxy vitrimer without hBN. These findings confirm that hBN and dynamic disulfide bonds operate through distinct yet complementary mechanisms, yielding a smart coating with heat-activated self-repair and superior corrosion protection.