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Spider silk secrets could spin cheaper fibers

MIT researchers have untangled some of the mysteries of sturdy spider silk in hopes of emulating it in a cheap, synthetic form.

Scientists (and people prone to bumping into spider webs) have long noticed the stunning strength of the arachnid bug catchers. Now, a group of MIT researchers think they've unraveled the mystery of what makes the structures so sturdy, and they hope to emulate--and even exceed--them in a synthetic form.

spider web
Courtesy Nicolas Demars via MIT

The team has concluded, ironically, that the silk's strength results from an unusual arrangement of inherently weak hydrogen bonds--in other words, location, location, location.

This particular layout of tiny silk nanocrystals lets the hydrogen bonds work cooperatively to reinforce adjacent chains against external forces. The bonds break gradually, and quickly re-form when they fail.

The size of the silk nanocrystals is important to the equation as well, the scientists found. When the crystals are about three nanometers (billionths of a meter), the material is ultra-strong and ductile. But at five nanometers, it becomes weak and brittle.

The MIT researchers used computer models to simulate the structure and interactivity of the silk molecules. They publish their findings in this week's issue of Nature Materials.

Markus Buehler, an MIT professor of civil and environmental engineering who led the research, says the findings could lead to novel, high-performance fibers or tissue replacement materials made from readily available, inexpensive elements. For example, he and his team are 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.