Whether you realize it or not, chances are you have a piece of cotton in your pocket or purse right now. And not just any piece of cotton, but one of the most sophisticated items of its kind in human history.
It’s paper money.
Unlike most paper, which is derived from wood cellulose, paper money is made of cotton, for reasons that benefit us all.
Cotton “not only gives it greater strength and stops it from disintegrating in the rain and washing machines but . . . it is also one of the best anti-counterfeit measures because it is hard to fake with wood-based paper,” writes author Mark Miodownik, a materials scientist, engineer and professor.
His new book, “Stuff Matters,” looks at 10 key materials from human history, and the innovations surrounding them — including our using cotton instead of wood for money to the Japanese developing steel alloys to create samurai swords that didn’t snap.
Such creative use of materials will shape the future as well, creating items that are stronger and smaller than ever before. Here’s some of the “stuff” that Miodownik says will change the way we live:
Self-healing concrete
Ancient Roman attempts at using concrete were stymied by the substance’s tendency to crack. This problem wasn’t solved until 1867, when a Parisian gardener named Joseph Monier “embedded loops of steel inside concrete” in order to make strong pots for his plants.
Unbeknownst to Monier, concrete expands and contracts at “almost the same rate” as steel, making them logical partners. In trying to make a simple flowerpot, Monier accidentally invented reinforced concrete, “by a long way the cheapest building material in the world.”
With “half of the world’s structures” now made from concrete, it’s essential for concrete to be dependable, and even, when needed, self-healing, Miodownik writes.
Self-healing concrete came about after scientists discovered bacteria living in a volcanic lake where “previously it had been thought that no life could exist.” One form of the bacteria, it turned out, could “excrete the mineral calcite, a constituent of concrete.”
Embedding this bacteria into concrete, along with starch to feed it, allows the concrete to fix itself.
“Under normal circumstances these bacteria remain dormant,” Miodownik writes. “But if a crack forms, the bacteria are released from their bonds, and in the presence of water they wake up and start to look for food. They find the starch, and this allows them to grow and replicate. In the process they excrete calcite . . . [which] bonds to the concrete . . . and spans the crack.”
There is also concrete cloth, which “comes in a roll and needs only water . . . to harden into any shape you like.” This has important applications for “disaster zones, where tents made from rolls of concrete can create a temporary city in a matter of days.”
The latest innovation in this area is self-cleaning concrete, which contains transparent titanium-dioxide particles that absorb UV light, causing them to “create free-radical ions, which break down any dirt that comes into contact with them.”
Walls of smoke
Of all the materials and inventions in the book, the one that has Miodownik most excited is silica aerogel. “The lightest solid in the world,” it is 99.8 percent air and “resembles solid smoke.”
Silica aerogel was developed in the 1930s when a chemist named Samuel Kistler figured out that jelly was a liquid trapped in a solid skin, and found a way to replace that liquid with a gas while keeping the jelly’s structure intact.
He replicated this with materials including silica, alumina, nickel tartrate, agar and even egg whites, allowing him to create “egg aerogel: the lightest meringue in the world.”
Silica aerogel, which Miodownik notes is “the best thermal insulator in the world,” has been used by NASA to insulate spacecraft and collect space dust.
Overall, aerogel has been woefully underused for several reasons, including cost. But its potential, writes Miodownik, is vast.
“[It] could be used to make the warmest but lightest blankets in the world,” and “would be perfect for outdoor clothes and boots designed for extreme environments. They could even replace the foam soles in sports shoes that make that type of footwear so springy.”
For Miodownik, aerogel serves as a reminder of just how exciting materials science can be and how important it is for society moving forward.
“If ever there was a material that represented mankind’s ability to look up to the sky and wonder who we are, to turn a rocky planet into a bountiful and marvelous place, to explore the vastness of the solar system while speaking of the fragility of human existence, it is aerogel.”
Transparent cloth
Other materials advancements are occurring in the field of nanotechnology — science conducted at the level of the nanometer, which is one-billionth of a meter. (If you’re reading this in print, this page is about 100,000 nanometers thick.)
Working at this scale, “materials scientists are starting to design structures that . . . can bend light any way they want.”
One result of this has been “the first generation of invisibility shields, which when surrounding an object bend light around it so that whichever direction you try to observe it, it appears to vanish.”
Carbon to space
While carbon had already given us the world’s hardest substance in the diamond, and one of its most useful in graphite, it turns out even diamonds were just scratching the surface of the material’s potential.
Carbon-fiber composite was created by “spinning graphite into a fiber,” then “encasing the fibers in epoxy glue.” The result was an incredibly strong material that has dominated sports and air travel, replacing aluminum in the building of aircraft and aluminum and wood for tennis racquets.
Bicycle racing was also turned upside down by the materials, as bikes made of the composite were so fast they were perceived as being unfair to other riders.
“In 1996,” Miodownik writes, “Chris Boardman rode 56.375 kilometers in one hour and provoked an outcry from the International Cycling Union. They promptly banned the use of these carbon-fiber-inspired designs, so worried were they by how radically the bikes would change the nature of the sport.”
The material is also changing the sport of running, as “more and more disabled athletes are using carbon fiber transtibial artificial limbs.”
In 2008, The International Association of Athletics Federations, feeling this gave disabled runners an unfair advantage over the able-bodied, tried to have them banned from competition but were overturned by arbitrators. Oscar Pistorius, who ran in the 2012 Summer Olympics before more recently finding greater fame for sadder reasons, ran on carbon-fiber artificial legs.
Further innovations using this material are certain, as its strength and reliability have been so admired that scientists are plugging it into their grandest dreams.
There is currently a quest among scientists to design and build a space elevator, “a structure linking a point on the equator to a satellite in geostationary orbit directly above it.” If the Space Elevator came to be, Miodownik believes it would “democratize space travel at a stroke, allowing people and cargo to be transported into space with ease and with an almost negligible energy cost.”
What’s needed for this is a “36-kilometer-long cable connecting a satellite to a ship floating in the ocean at the Earth’s equator.”
Scientists have determined that this is theoretically possible but would require “a material so strong that a single thread of it could be used to lift an elephant.”
At present, carbon fiber could “only lift a cat,” but scientists believe that the material — which in its present design is “full of defects” — has the potential to become the miracle thread they need.
“Theoretical calculations make clear that if a completely pure carbon fiber could be engineered, then its strength would be much higher, exceeding the strength of diamond.”
Another carbon-based material showing great promise is graphene, a two-dimensional version of graphite which is “the thinnest, strongest and stiffest material in the world; conducts heat faster than any other known material [and] can carry more electricity faster and with less resistance than any other material.”
Since graphene is still fairly new — about a decade old — and costly to produce, it remains to be seen exactly what its uses will be. But it’s worth noting that graphene-based innovations are a large part of the current patent fights between Apple and Samsung, as graphene can be used for touchscreens, bendable computers and more.
Miodownik even believes that graphene has the potential to possibly replace the basic building block of the computer generation, the silicon chip.
“Its extreme thinness, transparency, strength and electronic properties,” he writes, “mean also that it may end up being the material of choice for touch interfaces of the future, not just the touch screens we are used to but perhaps bringing touch sensitivity to whole objects and even buildings.”