A Bionic “Scaly” Structure: Based on Tannic Acid/Zn ²⁺ Self‐Assembly, Enhances the Interfacial Properties and Ultraviolet Resistance of Carbon Fiber/Epoxy Composites

Inspired by the spine structure on the back of hedgehogs, self‐assembled tannic acid (TA) and Zn ions (Zn 2+ ) are used to construct a bionic “scaly” structure on the surface of carbon fiber (CF) to improve the performance of CF/epoxy resin (CF/EP) composites. TA, as a bio‐based polyphenolic compound, is coordinated with Zn 2+ to form a TA/Zn 2+ complex with strong adhesion, which significantly improves its ultraviolet (UV) resistance. The interfacial properties of the composites are remarkably improved by enhancing the surface roughness and wettability of CF. Compared with the pristine composites, interlaminar shear strength (ILSS) and flexural strength of the modified composites increase by 44.96% and 50.43%, respectively. Noteworthy, the ILSS of the modified composites remains above 95% after a continuous week of UV ageing treatment. This research provides a new strategy for the interface design of high‐performance CF resin matrix composites for broadening the application in outdoor or strong UV environment.