Engineering professor Nicholas Kotov almost dubbed it "plastic steel," but the new material isn't quite stretchy enough to earn that name. Nevertheless, he says its further development could lead to lighter, stronger armor for soldiers or police and their vehicles. It could also be used in microelectromechanical devices, microfluidics, biomedical sensors and valves and unmanned aircraft. Kotov and other U-M faculty members are authors of a paper on this composite material, "Ultrastrong and Stiff Layered Polymer Nanocomposites," published in the Oct. 5 edition of Science. The scientists solved a problem that has confounded engineers and scientists for decades: Individual nano-size building blocks such as nanotubes, nanosheets and nanorods are ultrastrong. But larger materials made out of bonded nano-size building blocks were comparatively weak. Until now. "When you tried to build something you can hold in your arms, scientists had difficulties transferring the strength of individual nanosheets or nanotubes to the entire material," Kotov said. "We've demonstrated that one can achieve almost ideal transfer of stress between nanosheets and a polymer matrix." The researchers created this new composite plastic with a machine they developed that builds materials one nanoscale layer after another.The polymer used in the construction is polyvinyl alcohol. Picking the right material was important, because the polymer and clay form strong hydrogen bonds that Kotov calls "the Velcro effect," because if they are broken they reform easily in a new place.
Transparent, but strong as steel
University of Michigan researchers have developed a new plastic that sounds pretty amazing -- a composite plastic that they tout as being as strong as steel but lighter -- and transparent! The material is made of layers of clay nanosheets and a water-soluble polymer. The molecular structure mimics a brick-and-mortar design found in seashells.
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