MIT engineers have developed a new metamaterial that is both strong and stretchy, overcoming the usual trade-off between stiffness and flexibility.
The material starts as a rigid, brittle polymer but is printed into a precise double-network structure. This design combines stiff microscopic struts with a softer woven architecture, allowing it to stretch over four times its original size without breaking. In contrast, the same polymer in other forms would easily crack.
Researchers believe this design could be applied to ceramics, glass, and metals, enabling the creation of flexible yet tough products. Potential uses include tear-resistant fabrics, bendable semiconductors, stronger electronic packaging, and scaffolds for tissue repair.
Like other researchers, the research team typically designs metamaterials using microscopic lattices made from polymers, such as plexiglass or ceramics, creating structures with high strength and impact resistance.
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A few years ago, Portela wondered if a ‘rigid material’ could be patterned to make it softer and stretchier.’ Traditionally, metamaterial research focused on maximizing stiffness, but he wanted to explore the ‘soft matter realm.’
Instead of conventional lattice-based designs, his team printed an interwoven, spring-like structure. Although the base material was stiff, the ‘woven design’ made the final metamaterial’ soft and rubbery’ but lacked strength.
To improve it, the team turned to “hydrogels,” soft yet rigid materials composed primarily of water. Researchers had already developed “double-network hydrogels,” which combine a stiff molecular structure with a soft, flexible network. Portela and his colleagues wondered if this approach could be applied to “metamaterials,” leading to a breakthrough in creating “strong and stretchy materials.”
MIT researchers developed a new ‘metamaterial’ by combining two microscopic structures:
- A ‘rigid grid-like framework’ of struts and trusses.
- A ‘woven coil pattern’ wrapping around the grid.
Both structures are made from acrylic plastic and printed simultaneously using two-photon lithography, a high-precision laser printing method.
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The team tested samples, stretching them with a ‘nanomechanical press’ while recording high-resolution videos to analyze how the material deformed and tore.
Results showed that their ‘double-network metamaterial’ could stretch ‘three times its length,’ making it ’10 times more flexible’ than conventional designs. This stretchiness comes from the ‘interaction between rigid struts and flexible coils’, allowing it to resist breaking even under stress.
Imagine the material as a ‘tangle of spaghetti woven around a solid lattice.’ When the rigid lattice cracks, the broken pieces mix with the tangled fibers, increasing friction and spreading stress.
Because the ‘softer fibers absorb the stress unevenly,’ a crack is less likely to tear through the material quickly. The researchers also found that adding small holes to the design helped dissipate stress even more, making the material stretchier and harder to break.
By incorporating ‘defects’ into their design, the researchers doubled the material’s stretch and ‘tripled its energy dissipation,’ creating something that is both stiff and tough—an unusual combination.
To help engineers predict and optimize metamaterial performance, they developed a computational framework that models the behavior of different patterns of stiff and stretchy networks. This blueprint could be ‘useful for designing tear-proof textiles and fabrics,’ pushing the boundaries of durable yet flexible materials.
Journal Reference:
- Surjadi, J.U., Aymon, B.F.G., Carton, M. et al. Double-network-inspired mechanical metamaterials. Nat. Mater. (2025). DOI: 10.1038/s41563-025-02219-5
