IRG-II Highlight
How the weak becomes strong: spider silk reveals a paradox of super-strength
Image: Rendering of the nanoscale structure of silks with beta-sheet nanocrystals shown in yellowish color (right), including a detailed view of the semi-amorphous domains between the beta-sheet nanocrystals (left). |
Authors: M. Buehler (MIT)
Since its development in China thousands of years ago, silk from silkworms, spiders and other insects has been used for high-end, luxury fabrics as well as for parachutes and medical sutures. Now, MRSEC supported researchers are untangling some of its most closely guarded secrets, and explaining why silk is so strong, a question that has remained unresolved. Buehler and co-workers of the MIT MRSEC IRG-II have found that the key to silk's pound-for-pound toughness, which exceeds that of steel, is its beta-sheet crystals, the nano-sized cross-linking domains that hold the material together. Using computer models to simulate exactly how the components of beta sheet crystals move and interact with each other, they found that an unusual arrangement of hydrogen bonds -- the “glue” that stabilizes the beta-sheet crystals--play an important role in defining the strength of silk.
Buehler and his team are now looking at the possibility of synthesizing materials that have a similar structure to silk, but using molecules that have inherently greater strength, such as carbon nanotubes.
S. Keten, Z. Xu, B. Ihle & M.J. Buehler. Nanoconfinement controls stiffness, strength and mechanical toughness of β-sheet crystals in silk. Nature Materials 9, 359-367 (2010).
