Exploring the Interlocking Transcrystalline: Forming a New Structure of Transcrystalline for Improved Mechanical Performance of Carbon Fiber Reinforced Polyether Ether Ketone Composites

Carbon fiber‐reinforced polyether ether ketone (CF/PEEK) composites suffer from pronounced mechanical anisotropy, particularly poor interlayer strength perpendicular to fiber alignment, limiting their structural reliability. Inspired by the crack‐resistant interlocking architecture of diabolical ironclad beetle exoskeletons, we propose a biomimetic strategy to engineer three‐dimensional interlocking transcrystalline (ITC) networks via shear‐induced flow processing. By systematically regulating crystallization dynamics, we established optimal conditions for ITC formation, achieving enhanced crystal interlocking density compared to conventional transcrystalline structures. The resulting composites exhibit significantly improved transverse tensile strength, outperforming standard CF/PEEK prepregs by over threefold. Mechanistic analysis reveals that the ITC architecture concurrently restricts crack initiation through transcrystalline mechanical interlocking and dissipates stress through lamellar‐scale molecular reorientation, constituting a multi‐scale toughening mechanism. This bioinspired crystallization control method advances the design of high‐performance thermoplastic composites, bridging the gap between anisotropic material limitations and applications requiring multidirectional load‐bearing capacity, such as aerospace components and biomedical devices.