What’s bigger than the Statue of Liberty? Big Ben. What’s bigger than Big Ben? Hyperion, of course! The world’s tallest redwood tree, Hyperion, is still young by tree standards (“only” 600 years old), but is already towering above its fellow trees at nearly 380ft. While humankind has spent centuries striving to build the tallest buildings; trees have been doing so with ease for literal millenia. Their secret has so far eluded us, but a new discovery may change all that.
The key to plants’ success is a complex organic polymer called lignin. This polymer is deposited in the cell walls of almost all land plants. It is the second most abundant natural polymer in the world (cellulose is first, in case you were curious.) We’ve known about lignin since the early 1800s, but it’s difficult to study because there are a plethora of possible bonding patterns between the molecules in these polymers.
Lignin is so important because it increases the mechanical strength of molecules by binding all the molecules together, so that even Hyperion, at 379ft tall, can stand for hundreds or thousands of years. So what happens if we manipulate that power?
Scientists at University of Maryland have created what they’re calling “Superwood:” an ultra-thin, ultra-strong, and ultra-tough wood created through a special treatment process. They take any type of wood (even Balsa wood, the softest of them all, can be made into superwood,) remove some (not all) of the lignin, and then compress the wood at 150 degrees Fahrenheit with intense pressure. This process compresses the wood’s cellulose “so tightly that it reduces its thickness to one-fifth of its size;” this creates an “extremely strong hydrogen bond, which is what gives the super wood its strength.”
The key in this process is in the lignin. Lignin, because it acts as a bonding agent, needs to be removed in order for the cellulose to compress. However, because lignin also gives wood its strength, there’s a careful balance between removing enough lignin to compress but not enough to weaken. Scientists need to take out exactly the right amount in order for the wood to be made truly “super.”
This process is far easier than you might imagine. Removing the lignin is as simple as resting the wood in a chemical solvent that breaks down those bonds. Once about half the lignins are removed, the wood is compressed with heat. And there you have it: “Superwood!” The wonder of this process is that it’s so simple, it could easily be mass produced without a high price tag.
“Superwood” is so incredible that it rivals steel in its strength and endurance. We’re not kidding: in a show of its toughness “the team fired bullets against two pieces of the same type of wood and while the bullet pierced the untreated wood completely, the superwood block, of the same thickness and size, stopped it completely.” And with cheaper production costs, “superwood” could become a significant competitor for traditional building materials like steel, titanium, or carbon fibers. Imagine a day when cars, airplanes, even skyscrapers could be made of wood!
“Superwood” is a great example of how polymers can transform something ordinary into something extraordinary. We’re excited to see where this development takes us in the future.