High-Performance Crack-Resistant Elastomer with Tunable "J-Shaped" Stress-Strain Behavior Inspired by the Brown Pelican.

The gular sac tissue of brown pelican featured by the curvy pattern of fibers has an excellent combination of strain-stiffening behavior and fracture resistance. We develop an embroidery-reinforcement and solvent-welding strategy to fabricate a biomimetic elastomer with similar structure to that of the gular sac tissue. The embroidery reinforcement enables a well-designed biomimetic pattern of aramid fibers, and the solvent welding induces strong interfacial interaction between the aramid fibers and polyurethane matrix. This strategy endows the composite with excellent strain-stiffening behavior, fracture resistance, mechanical strength, and toughness, which are even better than the living prototype. Finite elements analysis reveals that the curvy pattern and strong interfacial interaction are crucial for both the J-shape behavior and the mechanical properties. The facile and robust strategy can be extended to other fibers reinforced polymers and should be promising for development of strong and tough soft materials with "J-shape" behavior.