Stuff Matters: Exploring the Marvelous Materials That Shape Our Man-Made World

by Mark Miodownik

In the case of gold alloys, you might wonder where the silver atoms go. The answer is that they sit inside the gold crystal structure, taking the place of a gold atom, and it is this atom substitution inside the crystal lattice of the gold that makes it stronger. Alloys tend to be stronger than pure metals for one very simple reason: the alloy atoms have a different size and chemistry from the host metal’s atoms, so when they sit inside the host crystal they cause all sorts of mechanical and electrical disturbances that add up to one crucial thing: they make it more difficult for dislocations to move. And if dislocations find it difficult to move, then the metal is stronger, since it’s harder for the metal crystals to change shape. Alloy design is thus the art of preventing the movement of dislocations.

Because Gold itself is a soft metal, most jewelry isn't pure gold but instead has a small percentage of silver or copper. Not only does adding an alternate metal make the final product harder but it also changes the overall color, with silver making the gold whiter and copper making it redder. The more they're used, the more pronounced the color becomes.

For, in the end, Brearley did manage to create cutlery from stainless steel, and it’s the transparent protective layer of chromium oxide that makes the spoon tasteless, since your tongue never actually touches the metal and your saliva cannot react with it; it has meant that we are one of the first generations who have not had to taste our cutlery.

Stainless steel was accidentally discovered through multiple attempts at trying to manufacture stronger steel. Only noticed due to having remained in a pile of rejected attempts where the surrounding pieces had all rusted away.

Most paper starts out life as a tree. A tree’s core strength derives from a microscopically small fiber called cellulose, which is bound together by an organic glue called lignin. This is an extremely hard and resilient composite structure that can last hundreds of years. Extracting the fibers of cellulose from the lignin is not easy. It is like trying to remove chewing gum from hair. Delignification of wood, as the process is called, involves crunching up the wood into tiny pieces and boiling them at high temperatures and pressures with a chemical cocktail that breaks down the bonds within the lignin and frees up the cellulose fibers. Once achieved, what is left is a tangle of fibers called wood pulp: in effect, liquid wood—at a microscopic scale it resembles spaghetti in a rather watery sauce. Laying this on to a flat surface and allowing it to dry yields paper. This basic type of paper is raw and brown. Making it white, sleek, and shiny requires a chemical bleach and the addition of a fine white powder such as calcium carbonate in the form of chalk dust. Other coatings are then added to stop any ink that is laid on top of the paper from being sucked too far into the cellulose mesh, which is what causes ink to bleed. Ideally the ink should penetrate a small amount into the surface of the note paper and then dry almost instantly, depositing its cargo of colored molecules, which sit there embedded in the cellulose mesh, creating a permanent mark on the paper.

The reason paper turns yellow is due to Lignin reacting with oxygen in the presence of light, chromophores is what's created as a result. Another neat thing is that the smell of old books that we've come to love is in fact the breakdown of chemical compounds... basically, we enjoy the smell of rotting paper. lol

concrete doesn’t dry out. Quite the opposite, water is an ingredient of concrete. When concrete sets, it is reacting with the water, initiating a chain of chemical reactions to form a complex microstructure deep within the material, so that this material, despite having a lot of water locked up inside it, is not just dry but waterproof. The setting of concrete is, at its heart, an ingenious piece of chemistry, which has powdered rock as its active ingredient. Not every type of rock will work. If you want to make your own concrete you need some calcium carbonate, which is the main constituent of limestone, a rock formed from the compressed layers of living organisms over millions of years and then fused together by the heat and pressure of the movement of the Earth’s crust.

As this reaction is taking place, the gel that forms inside cement is constantly changing as the solid internal skeleton grows and further chemical reactions take place. That skeleton is comprised of "fibrils that grow and meet, they mesh together, forming bonds and locking in more and more of the water until the whole mass transforms from a gel to a solid rock. These fibrils will bond not only to each other but also to other rocks and stones, and this is how cement turns into concrete."

But no, the calcium silicate fibrils inside concrete stick not just to stone but also to metal.

Discovered in an attempt to make stronger pots to replace the long standing clay ones.

But concrete can suffer from a more pernicious type of damage. This occurs when lots of water gets into concrete and starts to eat away at the steel reinforcement. The rust expands inside the structure, creating further cracking, and the whole internal steel skeleton can be compromised. It is particularly likely to happen in the presence of saltwater, which destroys the iron hydroxide protection and rusts the steel aggressively. Concrete bridges and roads in cold countries, which are regularly exposed to salt (such as is used to clear snow and ice), are vulnerable to this type of chronic deterioration.

The reason the internal steel skeleton within concrete doesn't erode is because they expand and contract at nearly the same exact rate.

These bacteria were also found to be extremely tough and able to survive dormant, encased in rock, for decades. Self-healing concrete has these bacteria embedded inside it along with a form of starch, which acts as food for the bacteria. Under normal circumstances these bacteria remain dormant, encased by the calcium silicate hydrate fibrils. 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 around for food. They find the starch that has been added to the concrete, and this allows them to grow and replicate. In the process they excrete calcite, a form of calcium carbonate. This calcite bonds to the concrete and starts to build up a mineral structure that spans the crack, stopping further growth of the crack and sealing it up. It’s the sort of idea that might sound good in theory but never work in practice. But it does work. Research now shows that cracked concrete that has been prepared in this way can recover 90 percent of its strength thanks to these bacteria. This self-healing concrete is now being developed for use in real engineering structures.

Nevertheless dark chocolate isn’t overly sweet; sometimes it’s not sweet at all. This is because at the same time that the sugars are released by the melting cocoa butter, so are chemicals known as alkaloids and phenolics from the cocoa powder. These are molecules such as caffeine and theobromine, which are extremely bitter and astringent. They activate the bitter and sour taste receptors and complement the sweetness of the sugar.

Silica aerogel, the lightest solid in the world, which is 99.8 percent air.

Discovered in an attempt to understand the structure of jelly.

When light from the sun enters the Earth’s atmosphere, it hits all sorts of molecules (mostly nitrogen and oxygen molecules) on its way to Earth and bounces off them like a pinball. This is called scattering, which means that on a clear day, if you look at any part of the sky, the light you see has been bouncing around the atmosphere before coming into your eye. If all light was scattered equally, the sky would look white. But it doesn’t. The reason is that the shorter wavelengths of light are more likely to be scattered than the longer ones, which means that blues get bounced around the sky more than reds and yellows. So instead of seeing a white sky when we look up, we see a blue one.

So when you hold a piece of aerogel in your hand, it is, in a very real way, like holding a piece of sky.

<3

So why is it that glass has this apparently miraculous property of transparency? How is it that light can travel through this solid material at all, while most other materials will not allow it? After all, glass contains all of the same atoms that make up a handful of sand. Why in the form of sand should they be opaque and in the form of glass transparent and able to bend light?

This idea of electrons not being able to move between rows (or energy states, as they are called) unless the energy exactly matches is the theory that governs the atomic world, called quantum mechanics. The gaps between rows correspond to specific quantities of energy, or quanta. The way these quanta are arranged in glass is such that moving to a free row requires much more energy than is available in visible light. Consequently, visible light does not have enough energy to allow the electrons to upgrade their seats and has no choice but to pass straight through the atoms. This is why glass is transparent.

This new generation of toughened glass has a layer of plastic in its middle, which acts as a glue keeping all the shards of glass together. This layer, known as a laminate, is also the secret behind bulletproof glass, which is essentially the same technology but with several layers of plastic embedded at intervals within the glass. When a bullet hits this material, the outermost layer of glass shatters, absorbing some of the bullet’s energy and blunting its tip. The bullet must then push the glass shards through the layer of plastic beneath it, which flows like tough treacle, thus spreading the force over a wider area than the point of impact. No sooner has it got through this layer than the blunted bullet encounters another layer of glass, and the process starts all over again.

Perhaps it is because we look through it rather than at it that glass has not become part of the treasured fabric of our lives. The very thing that we value it for has also disqualified it from our affections: it is inert and invisible, not just optically, but culturally.

The simplest thing a carbon atom can do is share each of these four electrons with another carbon atom, forming four chemical bonds. This solves the problem of its active four electrons: each electron is partnered off with a corresponding electron, belonging to another carbon atom. The crystal structure produced is extremely rigid. It is a diamond.

Just for starters, graphene is the thinnest, strongest, and stiffest material in the world; it conducts heat faster than any other known material; it can carry more electricity, faster and with less resistance, than any other material; it allows Klein tunneling, an exotic quantum effect in which electrons within the material can tunnel through barriers as if they were not there. All this means that the material has the potential to be an electronic powerhouse, possibly replacing silicon chips at the heart of all computation and communication.

It was the potters of the East who solved the problem of fragility and porosity. Their first step was to realize that if earthenware was covered with a particular kind of ash, this ash would transform during firing into a glass coating that would stick to the outside of the pot. This glass skin would seal all the pores on the outside of the earthenware.

No doubt they tried all sorts of different mixtures, but eventually they hit upon a particular combination of kaolin and a few other ingredients, such as the minerals quartz and feldspar, which created a white clay and, when fired, a nice-looking white ceramic. This was no stronger than earthenware, but, unlike any other clay they knew, if they increased the temperature of the furnace to a very hot 1300°C, it did something strange. The clay turned into an almost watery-looking solid: a white ceramic that had a near perfectly smooth surface. It was quite simply the most beautiful ceramic that anyone had ever seen. It was also stronger and tougher than any ceramic had any right to be. It was so strong that cups and bowls could be made that were extremely thin, almost as thin as paper, without compromising their ability to withstand cracks. These cups were so fine that they were translucent. It was porcelain.

This is because much of what makes us older is not the age of our cells but the deterioration of the systems that generate them.

Cells are constantly being replaced with newer ones, therefore it is not that our cells age alongside us... but that imperfections have developed over the years and those cells pass on these growing imperfections to the newer generations.

This is the scale at which we encounter one of the greatest technological triumphs of the twentieth century: the silicon chip. These chips are tiny collections of silicon crystals and electronic conductors, and they are the basic engine of the electronic world. There are billions of them inside the many electronic machines that surround us—they play our music, they take our holiday photos, and they wash our clothes. They are the man-made equivalent of the neurons in our brains and exist at the same scale as the nucleus within our cells. Strangely enough they contain no moving parts, using only the electric and magnetic properties of materials to control the flow of information.

Because of this strong connection between the materials and their social role, the materials that we favor, the materials that we surround ourselves with, are significant to us. They mean something, they embody our ideals, they give us part of our identity.