Bio‐Inspired Carbon Fiber/Epoxy Composites With Interfacial Self‐Healing Ability Triggered by Electricity

ABSTRACT Microscale interface damage in composite materials often initiates structural failure and is challenging to repair. Self‐healing strategy offers a promising solution to this issue. In this study, we developed an electricity‐triggered self‐healing system based on carbon fibers (CF) coated with polydopamine (PDA) and Diels‐Alder (DA) adduct functionalized carbon nanotubes (CNTs‐DA) to endow composites with interfacial repairability. By modifying CF with PDA and CNTs‐DA, the resulting CF‐PDA‐CNTs‐DA established the thermally reversible DA linkages at the composite interface, which could be triggered by the electrothermal effect of CF and CNTs. Comprehensive characterizations confirmed that the PDA‐CNTs‐DA coating layer significantly ameliorated surface roughness, wettability, and polar groups of CF. Consequently, CF‐PDA‐CNTs‐DA/epoxy composites exhibited substantial improvement in interfacial and mechanical performances compared to neat CF/epoxy composites. The microdroplet test demonstrated that the reversible reformation of DA bonds enabled efficient interface self‐healing for CF‐PDA‐CNTs‐DA/epoxy composites, with an initial healing efficiency of 92.8% and retention of 72.3%–87.5% efficiency over five healing cycles. Furthermore, FT‐IR spectroscopy was employed to elucidate the underlying interfacial self‐healing mechanism. This strategy, combining the electrothermal effect of CF and CNTs with the thermally reversible ability of DA bonds, offers a promising pathway for designing high‐performance self‐healing composites with extended durability and reliability.