American Elephants


New Materials With Surprising Properties That Will Change Our World by The Elephant's Child

We don’t hear much about materials science. I’m not sure that I was aware that there is such an occupation as a materials scientist. And in the history of materials something new and useful has been as likely to be the results of a botched experiment than created on purpose.

Scientists are now more apt to work out the properties of a possible material on a computer before they ever get near a laboratory or a workshop. We now have several materials that are so new that we don’t really know how they will be used. But here are five new materials that have the potential to be transformative.

Graphene

I have written about the chance invention of graphene by Andre Geim and Konstantin Novosetov at Manchester University when they were playing around with scotch tape and a lump of graphite in 2004. That resulted in a shared Nobel prize, knighthood, and a £61m National Graphene Institute.

Graphene is an extraordinary material, immensely strong, flexible, transparent and flexible. This makes it extremely interesting for a next generation of electronic devices —rolled up and stuck in our pockets, sewn into our clothing, or night-vision contact lenses as suggested by Zhaohui Zhong at the University of Michigan. It is a material that seems to have huge potential, with application in all sorts of different areas. The money has poured in. The problem is production.

With graphene, everything from your refrigerator to your toothbrush could be hooked up to the internet. How do you deal with an internet of things—cheap simple, flexible and eventually disposable devices? It’s hard to get your mind around that.

Spider silk

When researchers discovered the fantastic strength and flexibility of spider silk, they began taking about spider silk as the perfect material from which to manufacture bulletproof vests, when they teased out the silk’s molecular structure.

“You can’t use spider silk to make a bulletproof vest. It’s too extensible. It would catch the bullet, but not before the bullet has passed through your body. Well bulletproof vests may be out, but the potential is amazing, when we can learn how to produce such a material as well as a spider.

Spider silk is made from a biopolymer called an aquamarine, which can be spun at room temperature 1,000 times more efficiently than plastics that need to be heated up and cooled down. By controlling the rate at which the silk is spun a spider can control the stiffness or flexibility of the fibers. The goal for researchers is to make other materials that mimic the spider silk’s amazing tricks.

Metamaterials

Remember Harry Potter’s invisibility cloak? Two research groups have published technical blueprints for making “metamaterials” which can change how light and other forms of radiation bend around an object, in a way similar to water flowing around a rock. An observer would see whatever was behind the object as if the object were not there, according to Professor Ulf Leonhardt of St Andrews University and published in the journal Science.

If you read a lot of science fiction or military thrillers, you can see the implications of such materials. And of course that leads to concerns about ethics, and in an era of privacy concerns, drones, and the NSA, such innovations might seem disruptive to society. You have to structure the material on a length scale that is short, so for visible light that means on a nano scale. Objects can be hidden on some wavelengths and not others, or only under specific conditions. Sounds like there’s a lot of work yet to be done here. But fascinating.

Shrilk

Well, what else would you call a material made from leftover shrimp shells and proteins derived from silk? Shrilk was inspired by research into the tough shells of insects. The coating is made from layers of a material called chitin and a protein called fibroin. In one arrangement the material is strong and rigid enough to form the insect’s protective exoskeleton. What intrigued the Harvard researchers  was that simple tweaks to the material—specifically the amount of water bound inside it —changed the behavior of the material dramatically. Without water the material is stiff, but with water the coating becomes very flexible.

Shrilk
(photo: Jon Chase/Harvard University)

Javier Fernandez and Don Ingber at the Wyss Institute used fibroin from silk worm and chitosan, a material similar to chitin, to make their first batch of shrilk. They played with the water bound inside the material to vary its properties. They can for strong, transparent sheets of shrilk that are biodegradable and enrich the soil like a fertilizer as it breaks down. You might not use the material to make a trash can that you will use for ten years, but a trash bag for yard waste would make sense.

The components are FDA approved for use in the body, where they could find a role as sutures, or as scaffolds for growing new tissues that dissolve when they are no longer needed. Strange new words makes it seem like science fiction. So you develop a material, and then invent the uses for it, and tweak the material for new uses. Complicated—if the trash bag seems too plebeian—I am using lots of little green bags made out of corn (too biodegradable) that allow me to throw kitchen scraps into the yard waste can for recycling, except anything wet makes the bag  create holes and all the kitchen scraps fall on the floor. We need some improvement here, but someone is currently making a fortune from the little green bags.

Stanene

Here’s a material that was designed on a computer, and its extraordinary behavior worked out from theory. Only now are researchers trying to make the stuff to see if it delivers on those promises in the real world.

Scientists at Stanford University call it a topological insulator. It is an insulator on the inside, and a conductor on the outside. Thin layers of stanene—or one-atom-thick sheets of tin—are essentially all surface and should conduct electricity with 100% efficiency.

Materials conduct electricity when electrons flow through them. However, in most materials, the electrons are held up by impurities and other features that give rise to resistance. This resistance generates heat, and so electronics must be cooled to stop them melting. Stanene promises to change all that. The structure of the material allows electrons to shoot along channels with no resistance whatsoever. Add a little fluorine and, according to Zhang, the material will have zero resistance at more than 100C (212F).

Shoucheng Zhang at Stanford created stanene virtually, and sees stanene as the natural successor to copper interconnects in computers. Atomically thin connections that don’t heat up would enable designers to miniaturize electronics even more. Ultimately stanene could replace silicon as a cheap and abundant material from which to make computer chips.

Our world is always changing around us. Sometimes we get real explanations of what is going on in the labs, sometimes we get threats of what will be—that turn out to be nothing much. These new materials seem truly promising.




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