Nietzsche said, "That which does not kill me can only make me stronger." Scientists have recently discovered that this may be literally true in the case of plastics, and it could be a real boon to OEMs.
Researchers affiliated with Duke University have created a new type of plastic that becomes stronger when torn, stretched, or otherwise abused. The secret lies in special mechanophores. Mechanophores are compounds that react to a mechanical stress (as opposed to something like light, or heat, or a chemical).
In a paper published in Nature Chemistry earlier this year (the catchily-titled "Mechanochemical strengthening of a synthetic polymer in response to typically destructive shear forces"), researchers described how -- by carefully arranging a series of carbon and bromine atoms -- a specially enhanced polybutiadiene material could rearrange its molecular structure when under mechanical duress in such a way that new, stronger bonds and chains are formed. In testing, researchers discovered that the material hardened two hundred-fold when it was mechanically stressed.
The principle is the same as that which governs much of the human body. When we exercise effectively, our muscles tear slightly; they become tender and sore. Gradually, however, these muscles replenish themselves where they have torn, rebuilding themselves -- ourselves -- stronger than they were before.
In the case of the researchers' enhanced polymers, the result is something sort of like a science fiction bad guy who just laughs and gets stronger when the heroes attack him, and the heroes are like, "It's not working! He's absorbing the energy!" and the bad guy keeps laughing and is like "Fools!" and then he eats a tank or something, and the heroes have to find another way to defeat him.
[Editor’s Note: The author watched a lot of cartoons in the 80s.]
Here, however, the researchers hope to use this new material for good instead of evil. Possibilities include plastic shopping bags that don't rip, cars and planes that don't get damaged, roads and bridges that stay resilient through the seasons, better reinforced buildings that stay sturdy through natural disasters, and more powerful prosthetics and other biomedical devices.
And, of course, unbreakable smartphones. At least, that's the one that seems to have the tech community most excited.
Smartphones, as anyone who has ever dropped or sat on one knows, are notorious for apparently being constructed of the most fragile material on Earth, including (I'm guessing) the soft spots of babies' heads. Consequently, we buy cheap plastic cases to protect our phones, which help a little bit, but usually not much. Ditto for our tablets and other mobile devices. In a world where mechanophores are adapted for use in smartphone components, we might see the day where accidentally dropping and stepping on your brand new phone doesn't automatically mean a trip to the repair shop.
“The idea that you can take destructive energy and turn it into constructive energy is pretty exciting,” says Stephen Craig, a Duke University chemistry professor whose research group, the Craig Group, worked on the project.
Of course, the Craig Group's work is not the stuff of infinite strength and unlimited power. Although the researchers did not push their enhanced material to its limits, Craig acknowledges that at some point the material would exhaust its ability to form new bonds; at that point, real damage would begin to accrue from mechanical stress. Besides which, the Group's work is far from over. The next step, says Craig, is to figure out how to reverse the hardening process to keep materials soft and flexible for shock resistance.
Indeed, the Craig Group's work has been cited as one example of why some OEMs have invested so much in plastics engineering and other high-ends materials science. Plastic is lightweight, it can be cheaply produced, it can be molded into complex shapes (even being utilized in 3D printing), and it is strong -- stronger, it turns out, than we could have previously imagined.
What with their flexibility and sustainability, high-end polymers are not just the materials of today's enterprise; they are the materials of the future.