Synergistic Strengthening and Toughening of Nacre‐Like Composites via Chiton‐inspired Sinusoidal Interlocking Interfaces

ABSTRACT Achieving synergistic strengthening and toughening in engineering materials remains a significant challenge. Although nacre‐inspired composites with brick‐and‐mortar structures exhibit high strength and toughness, the synergistic enhancement of these two properties is severely constrained by inadequately engineered interfaces. In this study, we innovatively integrate the sinusoidal interlocking interface found in chiton shells into brick‐and‐mortar architectures to overcome the inherent weakness of interfacial regions. Tensile test results reveal that the crossed sinusoidal interface morphology significantly enhances both strength and toughness of the bioinspired composites. Under the N 2‐ A 0.4 interface, the values of σ I , σ II , σ M , and toughness increased by 91.2%, 54.8%, 365.2%, and 170.9%, respectively. The integration of the sinusoidal interface from chiton shells eliminates low‐stress regions within brick‐and‐mortar structures, thereby enabling a synergistic enhancement of strength and toughness. Furthermore, the results indicate that the orientation of the sinusoidal interfaces plays a crucial role in determining the strength and toughness of composites. The underlying principle for the synergistic enhancement of strength and toughness in bioinspired composites lies in rationally optimizing the interlocking interfaces to balance load transfer and stress concentration. The unique bioinspired interface overcomes the weaknesses of brick‐and‐mortar architectures, offering a promising design strategy for the next‐generation ultra‐strong and tough composites.