Mussel‐Inspired Polydopamine Coating for Damage‐Free Anchoring of Carbon Black to Improve the Interface Performance of Carbon Fiber/Resin Composites

ABSTRACT Introducing carbon black (CB) into the fiber/resin interface region can further enhance the mechanical performance of carbon fiber reinforced polymer composite (CFRP). However, traditional methods of introducing CB often suffer from issues such as complex operations, excessive consumption of chemical agents and hidden harm to fiber strength. Inspired by the adhesion principle of mussels, a simple, green and efficient carbon fiber surface modification strategy has been proposed. The strategy leveraged the high adhesion and secondary reaction properties of dopamine (DA), utilizing non‐covalent and covalent cross‐linking interactions between polydopamine (PDA) and CB to construct a PDA/CB coating on the fiber surface. Due to the repairing effect of the PDA/CB coating on fiber surface defects and pores, as well as the constraint effect of covalent and non‐covalent interactions between PDA and CB, CF‐PDA/CB ultimately yielded a 13.45% enhancement in tensile strength (TS) compared to desized CF. Moreover, compared with desized CF composite, the interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) of the CF‐PDA/CB composite increased by 32.01% and 41.00%. This was attributed to the rough and highly reactive PDA/CB coating, which not only achieved excellent wetting properties between fiber and resin to enhance interfacial adhesion, thereby strengthening mechanical interlocking and chemical bonding interactions between the two, but also expanded the interfacial transition zone to promote stress transfer and energy dissipation. This research provides a promising approach for the recycling of carbon resources from scrap tires and the high‐value application of CB in high‐performance composites.