MIT engineers print synthetic “metamaterials” that are both strong and stretchy

Breaking the Trade-off Between Strength and Flexibility

Metamaterials are typically engineered for either stiffness or flexibility. MIT researchers have overcome this limitation by creating a 'double-network' architecture. By printing a combination of rigid microscopic struts and woven, spring-like coils, the team produced a material that can stretch to four times its size without shattering, despite being made from a traditionally brittle polymer.

Design and Mechanism

The material's structure, inspired by tough hydrogels, uses a high-precision 3D printing technique called two-photon lithography. When the material is pulled, the interaction between the rigid struts and the entangled, 'spaghetti-like' coils promotes friction and energy dissipation. This prevents cracks from propagating quickly through the structure. Interestingly, the researchers found that strategically adding 'defects' or holes into the pattern actually enhanced the material's stretchiness and toughness further.

Future Applications

This dual-network approach holds potential for creating new categories of functional materials. The team intends to apply this design to inherently brittle materials like ceramics, glass, and metals. Potential real-world applications include tear-proof textiles, flexible semiconductors, advanced electronic chip packaging, and compliant scaffolds for medical tissue repair.