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New resilient nanofiber bodes well for the future of stronger, tougher materials

A newly invented nanofiber may prove to be the resource industrialists have been seeking to provide stronger, tougher products. Scientists with the University of Nebraska-Lincoln have developed the potentially revolutionary fiber.

Spearheaded by Yuris Dzenis, McBroom Professor of Mechanical and Materials engineering with the university, a team was able to produce the new nanofiber through the process of electrospinning. The approach applies a high amount of voltage to polymer solutions until a jet of liquid expels. This allows for a continuous length of nanofiber to be created.

It was already known to Dzenis that thinning his material would make it stronger, but this time the material also became tougher, an uncommon result. Related to acrylic, the synthetic polymer appears to have a low crystallinity. Most nanofibers have a high crysallinity, which limits the pliability of a rigid internal structure. Dzenis’s fiber has no clearly defined internal structure and can thus absorb larger amounts of energy without fear of breaking.

“Our discovery adds a new material class to the very select current family of materials with demonstrated simultaneously high strength and toughness,” said Dzenis.

The nanofiber’s ability to be both strong and tough is an important distinction. To clarify, the general rule of thumb is typically that if an object is tough, it is not strong (and vice verse). A block of wood is strong, but the right amount of force—a karate chop from a Black Belt, for example—will break it. Conversely, a mattress requires great effort to destroy despite its malleability; it is tough, but its softness devalues its strength.

Such distinctions can be applied to more important products as well. A plane, for instance, could crash if its composite materials broke down. The lack of toughness can be waylaid by simply adding more materials, but doing so makes it heavier. A nanofiber that is both tough and strong can yield more resilient yet lightweight products (including the plane).

“If structural materials were tougher, one could make products more lightweight and still be very safe,” explained Dzenis, also using bulletproof vests as applicable examples. “To stop the bullet, you need the material to be able to absorb energy before failure, and that’s what our nanofibers will do.”

The University of Nebraska-Lincoln team received funding for their research from the National Science Foundation, the Air Force Office of Scientific Research, and the U.S Army Research Office Multidisciplinary University Research Initiative. Their findings are the cover story of April’s issue of the American Chemical Society journal ACS Nano, out this week.