Spider Silk
Very cool -- one of the more interesting substances out there is spider web silk. Much stronger than steel, it promises to be useful in a lot of applications. The problem is that until now, it has defied synthesis.
From
Extreme Tech:
MIT Labs Moves Ahead In Synthesizing Spider Silk
Polymeric nanocomposites, synthetic substances that are both strong and stretchy, like organic spider silk, have baffled scientists looking to replicate their unique properties. On Friday, a team from MIT's Institute for Soldier Nanotechnologies (ISN) announced they had devised a new way to create such Lycra-like materials in a lab.
Scientists have previously suggested that a mere pencil-thick strand of silk could actually stop a Boeing 747 in mid flight. The naturally occurring substance—on a weight basis—is stronger than even steel.
As early as 1996, DuPont started an advertising campaign in Scientific American about how they were studying the biopolymer structures of the spider webs. Yet more than 10 years later, fabricating these types of artificial silk-like substances in a lab has proven difficult for engineers.
There has been progress in creating materials that fulfill either the stretchy or strength quota, but never both at the same time, according to the MIT team responsible for new discovery.
"If you look closely at the structure of spider silk, it is filled with a lot of very small crystals," said Gareth McKinley, a professor of mechanical engineering and part of the group that devised the new method of producing the material.
"It's highly reinforced."
The secret of spider silk's combined strength and flexibility, according to scientists, has to do with the arrangement of the nano-crystalline reinforcement of the silk as it is being produced—in other words, the way these tiny crystals are oriented towards (and adhere to) the stretchy protein.
Emulating this process in a synthetic polymer, the MIT team focused on reinforcing solutions of commercial rubbery substance known as polyurethane elastomer with nano-sized clay platelets instead of simply heating the mixing the molten plastics with reinforcing agents.
According to McKinley, the process yields a nanocomposite that is randomly reinforced with these nano clay discs, making it very strong, yet also stretchy.
As with all things having to do with thin reinforced materials, the U.S. military has been closely monitoring MIT's progress. In fact, the research was funded by the U.S. Army. But interest in the new material doesn't stop there. Clothing and fabric companies could also benefit from the discovery as well as medical companies who make stents and other biomedical devices.
The corresponding research behind MIT's discovery appears in the January issue of Nature Materials.
The abstract for the paper is here:
High-performance elastomeric nanocomposites via solvent-exchange processing
Posted by DaveH at January 21, 2007 2:58 PM