Hyperbranched Poly(Aryl Ether Ketone)s Interface Modifiers for High‐Performance Carbon Fiber/ PEEK Composites

ABSTRACT Owing to the exceptional performance, carbon fiber reinforced thermoplastic composites (CFRTPs) are becoming increasingly popular in advanced industrial applications. However, further development is hindered by the poor interfacial bonding between carbon fibers and resins. In this study, three hyperbranched poly(aryl ether ketone)s (HBPAEKs) with different terminal groups were synthesized and employed as interfacial modifiers to enhance the interfacial interactions of composites. A synergistic modification strategy combining plasma pretreatment and HBPAEKs coating was adopted to regulate the surface activity, roughness, and chemical composition of the carbon fibers. The results indicate that HBPAEKs exhibit excellent solubility and wettability, significantly improving resin impregnation and reducing interfacial defects. The HBPAEKs‐F modified carbon fiber reinforced PEEK composite exhibited the best mechanical performance, achieving a longitudinal tensile strength of 1421 MPa, flexural strength of 1855 MPa, and interlaminar shear strength of 115.7 MPa, corresponding to improvements of 30%, 49%, and 51%, respectively, compared with those of unmodified composites. Microstructural analyses revealed that the enhanced interfacial strength originated from the hyperbranched architecture of the HBPAEKs, which promoted molecular chain entanglement with the PEEK and strong π–π interactions at the fiber–matrix interface. This study provides an effective strategy for the interfacial design of high‐performance thermoplastic composites.