EVERYTHING should look different by now. We should be surrounded by swarms of high-speed computers, each no bigger than a speck of dust. We should be living in houses that snap back into shape after an earthquake or a hurricane. We should be boarding elevators that can carry us into space. If you believed just half of what has been written about carbon nanotubes over the past decade, you might now be feeling a bit disappointed with the impact they have had on today ‘s world.
But you shouldn ‘t be. There ‘s a good chance you now own some nanotubes. Most American cars, not to mention a good number of European ones, contain them. If you ‘ve bought any electronics recently, its components may well have come to you in nanotube-laden packaging. And it won ‘t be long before you can go camping, gaze up at the stars and thank nanotubes for the electrical power that heated your supper. The revolution has happened you just didn ‘t notice.
There ‘s no doubting the potential of nanotubes. They might look like a bit of rolled-up, microscopic chicken wire, but this honeycomb lattice of carbon atoms is the stuff of engineers ‘ dreams. For instance, their electrical properties mean that nanotubes can be made into metals or semiconductors, depending on how you roll up the sheet of carbon atoms. Roll the carbon the way you roll a cigarette, with the edges touching along their length, and you have a nanotube that acts like a tiny metal wire conducting electricity. Wind the tube askew, like a paper straw, and you have a miniature semiconductor that could replace silicon transistors, the building blocks of chips.
What ‘s more, nanotubes conduct electricity better than copper, making them a contender for replacing the delicate wires that connect components together inside computer chips. Not only that, but they can carry heat far more efficiently than diamond, one of the best heat conductors around. So if you give processor chips a nanotube coating, you could pack billions of them together into a tiny space with little risk of them burning up.
Perhaps even more impressive are the mechanical properties of these lightweight structures. Nanotubes are over 50 times stronger than steel wire and only a quarter as dense. No matter how hard you squeeze a nanotube, it will bend and buckle without breaking, springing back into shape as soon as you let it go. So who can blame analysts for predicting the emergence of crash-proof cars, nanotube ropes for lassoing space junk, and bulletproof vests lighter than a silk camisole?
Indeed, the strangest thing about the nanotube story is not the hype but the history. Read textbooks, newspapers, magazines, even academic journals, and you ‘d think they were a recent invention. But nanotubes may already have been around for more than a century. A US patent granted in 1889 to two British men reveals how to make them using marsh gas better known these days as methane. The method is essentially the same as that used in industrial processes today, and produced “hair-like carbon filaments” for electric lighting. According to the patent, as well as having useful electrical properties, these filaments “may be bent and twisted into various shapes and will spring back to their original form on being released”. In the 1960s and 1970s a couple of research groups at the National Carbon company in Parma, Ohio, and the University of Canterbury in Christchurch, New Zealand, respectively also made and characterised carbon nanotubes.
The hype began much later in 1991, after Sumio Iijima and his colleagues created nanotubes at the research laboratory of the electronics multinational NEC in Tsukuba, Japan. Iijima ‘s “discovery” came just a few years after the surprise finding of buckyballs a new molecular structure for carbon and, perhaps more importantly, the publication of Eric Drexler ‘s book Engines of Creation. This raised the idea that nanotechnology, making machines on the nanoscale, could provide a solution to virtually any problem you might dream up. By the time Iijima made his announcement, nanotechnology was filtering into academic and government circles as something worth thinking about. Nanotubes were just what we had been waiting for a material to transform the world.
One organisation unimpressed by the 1991 hype was Hyperion Catalysis, a firm based in Cambridge, Massachusetts. Hyperion has been perfecting ways to produce nanotubes by the tonne since 1983. Today, 60 per cent of cars on American roads have fuel lines containing Hyperion ‘s carbon nanotubes. Their high conductivity dissipates any electric charge that might build up and generate a dangerous spark as the fuel flows past the nylon walls of the fuel line. If you own a Renault Clio or M gane, next time you polish it you ‘ll also be buffing some of Hyperion ‘s nanotubes. These are used to make the plastic wing panels so conductive that they can be earthed while the car is sprayed with paint droplets charged up to 20,000 volts. The droplets seek ground instead of floating away, making spray-painting more efficient and less polluting.
At present, Hyperion is the only company that churns out tens of tonnes of “multiwall” nanotubes every year. These consist of between 10 and 12 nested cylinders of carbon, each 10 micrometres long, and cost as little as 2 per gram. Hyperion only sells them incorporated into plastics, but there are plenty of other firms, such as Carbon Nanotechnologies in Houston and Sun Nanotech in Nanchang, China, that sell plain nanotubes by the gram.
Car manufacturers aren ‘t the only ones…