Surface Engineering of Carbon Fibers via Sequential Growth of Molybdenum Disulfide Nanosheets and POSS Nanocages for Interfacial Reinforcement

ABSTRACT Enhancing the interfacial adhesion between carbon fibers and polymer matrices is critical for achieving high‐performance carbon fiber reinforced polymer composites. In this work, a hierarchical hybrid interphase was constructed through the synergistic integration of in situ grown molybdenum disulfide (MoS 2 ) nanosheets, (3‐aminopropyl) triethoxysilane (APTES), and epoxy‐functionalized polyhedral oligomeric silsesquioxane (POSS). The rigid MoS 2 nanosheets were uniformly grown on the carbon fiber surface to form an interconnected nanosheet network, which increased the surface roughness and provided mechanical interlocking sites. Subsequently, APTES was introduced as a covalent bridging layer to graft reactive amino groups onto the fiber surface. Finally, epoxy‐functionalized POSS nanoparticles were chemically anchored onto the APTES layer via ring‐opening reactions, generating a highly cross‐linked hierarchical interphase. The synergistic effect of the rigid MoS 2 framework, flexible silane bridging layer, and rigid POSS nanocages effectively improved interfacial stress transfer and suppressed interfacial debonding. Compared with untreated composites, the interlaminar shear strength, flexural strength, and transverse fiber bundle tensile strength increased by 38.1%, 77.2%, and 91.5%, respectively. Fracture morphology analysis further revealed enhanced resin adhesion and crack deflection behavior at the interface. This work provides an effective strategy for engineering hierarchical interphases toward high‐performance polymer composites.