With graphene, carbon scores again

Updating Magic Universe

With graphene, magical carbon scores again

Today’s award of the physics Nobel Prize to Andre Geim and Konstantin Novoselov “for groundbreaking experiments regarding the two-dimensional material graphene” gives me the chance to update what I wrote about carbon honeycombs in Magic Universe, which was published a year before the graphene story broke in 2004.

In an earlier post I’ve rhapsodised about polycyclic aromatic hydrocarbons in the cosmos, and their relevance to the origin of life – see https://calderup.wordpress.com/2010/06/01/comets-and-life-2-2/ — but now it’s the terrestrial side of the carbon saga that makes the mind boggle. We’re talking about the familiar graphite that comes off the end of your pencil when you write, but now reduced to a layer just one atom thick.

The relevant story in Magic Universe is called “Buckyballs and nanotubes: doing very much more with very much less.” Starting with a nod to the geodesic dome designer Buckminster Fuller, who inspired the names of the football-like C₆₀ molecules, fullerenes or buckyballs, found in 1985, it proceeds from that discovery to the molecular basket-work of the carbon nanotubes, first made in 1991. Today’s update belongs after some cheerful speculations that followed.

Let your imagination rip

It is unlikely that anyone has yet guessed more than a small fraction of the technological possibilities latent in nanotubes. The molecules are far stronger than steel, and atomically neater than the carbon fibres used previously to reinforce plastics. Temperatures of 500 ^oC do not trouble them. Laced with metals, they can become superconductors, losing all resistance to the flow of an electric current at low temperatures. You can tuck atoms, or even buckyballs containing atoms, into nanotubes like peas in a pod. Doing chemistry with the ends may be able to provide useful links, handles or probes.

An intoxicating free-for-all followed [Sumio] Iijima’s discovery. Thousands of scientific papers about nanotubes, from dozens of countries around the world, opened up new chemistry, physics and materials science. As they pushed back the envelope of foreseeable applications, the patent lawyers were busy too.

The fact that nanotubes spontaneously gather into tough tangles is a virtue for some purposes. Rice University found a way of making nanotubes in bulk from carbon monoxide, which promises to bring down the cost dramatically. It encouraged predictions of first-order applications of the bulk properties of tangled nanotubes. They ranged from modest proposals for hydrogen storage, or for electromagnetic shields in mobile phones and stealth aircraft, to more challenging ideas about nanotube ropes reaching into space.

Such Jacob’s ladders could act as elevators to launch satellites. Or they could draw down electrical energy from space. That natural electricity could then spin up strong flywheels made of tangled nanotubes, until they carried as many megajoules as gasoline, kilo for kilo — so providing pollution-free energy in portable form.

The silicon microchip may defer to the carbon nanochip, for building computers and sensors. But that’s linear thinking, and it faces competition from people making transistors out of fine metallic threads. A multidimensional view of buckyballs and nanotubes perceives materials with remarkable and controllable physical properties that are also susceptible to chemical modification, exploiting the well-known versatility of the carbon atom. Moreover, living systems are the cleverest carbon chemists. It is fantasy, perhaps, but not nonsense, to imagine adapting enzymes or even bacteria to the industrial construction of nanotube machinery.

The new molecular technology of carbon converges with general ideas about nanotechnology — engineering on an atomic scale. These have circulated since the American physicist Richard Feynman said in 1959, ‘The principles of physics, as far as I can see, do not speak against the possibility of manoeuvring things atom by atom.’ Hopes at first ran far ahead of reality, and focused on engineering with biomolecules like proteins and nucleic acid, or on molecules designed from scratch to function as wheels, switches, motors and so on.

Anticipating the eventual feasibility of such things, one could foresee spacecraft the size of butterflies, computers the size of bacteria, and micro-implants that could navigate through a sick person’s body. The advent in the 1980s of microscopes capable of seeing and manipulating individual atoms brought more realism into the conjectures. Buckyballs and nanotubes not only added the element of surprise, but also opened up unlimited opportunities for innovators.

Symbolic of the possible obsolescence of metal technology are magnets of pure carbon, first created at Russia’s Institute for High Pressure Physics in Troitsk. Experimenters found that the partial destruction of a fullerene polymer by high pressure produces a material that is ferromagnetic at ordinary temperatures. In other words it possesses the strong magnetic properties commonly associated with iron.

‘Ferromagnetism of pure carbon materials took us completely by surprise,’ said Valery Davydov, head of the Troitsk research group. ‘But study of these materials in different laboratories in Germany, Sweden, Brazil and England convinces us that the phenomenon is real. It opens a new chapter in the magnetism textbooks.’

Unless you let your imagination rip you’ll have little hope of judging the implications of the novel forms of commonplace carbon. To find a comparable moment in the history of materials you might need to go all the way back to the Bronze Age, when blacksmiths in Cyprus made the first steel knives 3100 years ago. Who then would have thought of compass needles, steamships, railways or typewriters? As the world moves out of the Iron Age, through a possibly short-lived Silicon Age into the Carbon Age, all one can be confident about is that people will do very much more with very much less, as Buckminster Fuller anticipated. Any prospect of our species exhausting its material resources will look increasingly remote.

Update 2010: More amazement, with graphene

Buckyballs (left), nanotubes (centre) and graphene layers (right) all share the same honeycomb polycyclic molecular structure. Credit: Nobel Foundation.

In 2004 the pace quickened with the début of a third class of carbon lattice, graphene. Andre Geim and Konstantin Novoselov, Russian-born physicists working in the West, managed to obtain flakes of graphite just one atom thick, by picking them off with ordinary Scotch tape. Graphene is the thinnest material ever available, 97.7 per cent transparent to light yet impervious to any gas, very strong, and a brilliant conductor of heat and electricity. Modifying the electrical properties by doping pointed the way to graphene electronics.

If you made an almost invisible bag with a square metre of graphene it would weigh less than a milligram but you could carry a cat in it. By 2009, graphene sheets 7 metres wide were being manufactured. While some were dreaming of graphene-reinforced materials for cars, planes and spacecraft, others were making analogues of the graphene honeycomb from boron plus nitrogen or molybdenum plus sulphur.

It seems a little unfair that the discoverers of buckyballs and graphene now have the Nobel Prize, but Sumio Iijima missed out, for nanotubes.

At the end of that story in Magic Universe there’s a postscript that I reproduce because it’s relevant to my posts about why science is so slow. (See https://calderup.wordpress.com/2010/05/06/why-is-science-so-sloooow/ and https://calderup.wordpress.com/2010/08/05/why-is-science-so-sloooow-2/ )

Surprises mean unpredictability

A chemist’s wish, driven by curiosity, to simulate the behaviour of carbon in the atmosphere of a star, resulted in the serendipitous encounter with C₆₀, buckminsterfullerene. An electron microscopist’s accidental discovery of nanotubes followed on from this. The course of science and engineering has changed emphatically, with implications for everything from the study of the origin of life to reducing environmental pollution. What price all those solemn attempts to plan science by committees of experts?

Harry Kroto saw in buckyballs and nanotubes an object lesson in the futility of trying to predict discoveries, when handing out research grants. What possible merit is there in the routine requirement by funding agencies that researchers must say in advance what the results and utility of their proposed experiments will be? Why not just give the best young scientists access to the best equipment, and see what happens?

Among the vineyards of California’s Napa Valley, Kroto found the exact words he needed to convey his opinion. ‘There was a beaten up old Volvo in a parking lot and on the bumper was a truly wonderful statement that sums up my sentiment on all cultural matters and science in particular. It was a quotation from the Song of Aragorn by J.R.R. Tolkien:

‘Not all those who wander are lost.’

References

N. Calder, Magic Universe, pp. 100-103, Oxford UP 2003

Nobel Foundation announcement http://nobelprize.org/nobel_prizes/physics/laureates/2010/index.html#