Chiton‐Inspired Composites Synergizing Strength and Toughness Through Sinusoidal Interlocking Interfaces for Protective Applications

Introducing biological structures into materials design is expected to develop strong and tough structural materials. However, multiple interfaces are introduced simultaneously. They are always the weakest part of load transfer, becoming a critical vulnerability and failure-prone area. Here, it is the first found that the chiton achieves superior mechanical properties just by incorporating a unique sinusoidal interlocking interface into cross-lamellar architecture. These special interlocking interfaces make the chiton shell achieve damage delocalization and increase the resistance to crack initiation and propagation. Meanwhile, this "pre-engineered" path significantly increases the travel path of the cracks and balances the strength and toughness under quasi-static and impact loading. Inspired by this, a novel chiton-inspired composite is proposed. Through coupling the cross-lamellar structures and sinusoidal interlocking interfaces, its strength and toughness are increased by 88% and 107% under quasi-static loading, as well as by 17.8% and 52.4% under impact loading, respectively. These unusual interfaces make up the weak point of cross-lamellar structures and provide insights into the longer evolution of structural materials.