Interface Design Strategy for Improving Interfacial Properties and Achieving Interfacial Self‐Healing Capabilities in Carbon Fiber Composites Based on the Introduction of ZIF8 and Diels–Alder Adducts

ABSTRACT In this research article, the Diels–Alder (DA) cycloaddition adducts and zeolitic imidazolate framework 8 (ZIF8) were simultaneously introduced onto the carbon fiber (CF) surface to improve interface adhesions and endow the CF/epoxy (EP) composite with interface self‐healing properties. Fourier transform infrared (FT‐IR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), and other characterization techniques were carried out to verify the fabrication of carbon fiber grafted with ZIF8 and DA adducts (CF‐ZIF8‐DA). The introduced ZIF8 and DA adducts significantly ameliorated the surface roughness, active functional groups, wettability, and surface energy of CF. As a result, the interfacial and mechanical properties (interfacial shear, monofilament tensile, bending, and interlaminar shear strength) of the CF‐ZIF8‐DA/EP composite were dramatically increased by 90.2%, 7.8%, 22.1%, and 30.6% compared with the desized CF/EP composite, respectively. The micro‐droplet test verified that this surface modification process on CF could endow the designed composite with interface self‐healing properties through the reversible transformation of DA bonds. The first self‐healing efficiency of the CF‐ZIF8‐DA/EP composite was about 89.6%, while the composite still recovered with a relatively high self‐healing efficiency after five healing cycles. Furthermore, the interfacial self‐healing mechanisms were also explored in detail using FT‐IR spectroscopy. Thus, this novel strategy based on the introduction of ZIF8 and thermoreversible DA adducts will provide enormous potential in developing structural composites with high interface adhesion and excellent self‐healing performance.