Diamonds have a special relationship with fat. (Courtesy of the Laughlin girls.)There are very few things more irritating than walking back into the kitchen and finding you have burnt the toast. And yet, if there is a consolation to be found while contemplating the smoking blackened husk, it is that one can claim to have just satisfactorily performed a powerful demonstration that life is carbon-based. It is truly incredible that one can so easily pluck carbon out of a slice of bread, the very element whose flexible chemistry makes life on earth possible. Not that carbon in the form of charcoal is culturally revered. We don't go round wearing pieces of burnt toast in order to celebrate the most important element on earth.
Some other forms of carbon are used to make jewelry, however. Jet, a mineralized form of the monkey puzzle tree, can be carved and polished to a brilliant finish, and has a beautiful dark black luster. It has similar triboelectric properties to amber, and so is sometimes called black amber because of its ability to generate static charge and make hair stand on end. A perfect mysterious symbol, you might think, to remind us of the origins of life. But it is in fact associated with death. It was made fashionable in England in the 19thcentury by Queen Victoria, who mourned the death of her consort Prince Albert by wearing black clothes and jet jewelry for the rest of her life. There was a subsequent popular demand for jet from the rest of ghoulish Victorian England. Almost overnight the population of the Yorkshire town of Whitby stopped using the large local deposits of jet as a handy fuel and became famous for producing the jewelry of lament and sorrow. It can be no coincidence that Whitby was later the place where Bram Stoker wrote his Gothic masterpieceDracula.
Carbon fiber also has a distinctive aesthetic place in our culture. It used to be confined to high-tech sports equipment and deployed mostly as a composite in cylindrical form in the shafts of golf clubs, the masts of racing boats, and the frames of bicycles, where its high stiffness-to-weight ratio makes it superior to almost any other material. Soon its characteristic black plaid appearance became a synonymous with high-tech applications. Then the textile and aerospace communities joined forces and elevated it to one of the high priests of a new category of materials, technical textiles. Now the fibers are woven to have a wide range of patterned macrostructures that allow both a sophisticated control of physical properties and increased formability. The intricate weave of machine-embroidered carbon lace, or the triaxial and twill woven fabrics, adds a tailored quality to these materials reminiscent of a Savile Row suit.
The combination of an instantly recognizable aesthetic and extraordinary physical properties has attracted the attention of designers and architects. For instance, the architect Peter Testa has produced a design for a ‘Carbon Tower’, which comprises a double helix woven structure of pultruded and braided carbon fibers, stabilized by continuous braided tendons within the floor plates. The radical design calls for a complete shift away from the modern building practice of separating the structural members of the building from its external shell. Such a building would essentially be woven like a cocoon. The advantages of such a structure are not immediately clear though, except that it makes a vast range of new building geometries possible.
Another advantage, that mimics the development of living organisms, is that sensors and communications cables can be woven into the building during construction. This is already happening in wearable technology fabrics designed for fashion and medicine (see, for example, the article by Markus B. Schubert and Jürgen H. Werner on page 42). For instance, Philips has a developed a material with woven carbon fibers the resistivity of which can be monitored to track strain and damage in the structure. The military has been using graphite fabrics in chemical suits for many years because of their ability to absorb toxic agents. Now the medical industry is becoming interested in incorporating graphite into hospital clothing to reduce wound smell and airborne infection.
Despite these carbon-fiber-based innovations and the growing potential of carbon nanotubes, the most highly valued form of carbon is still diamond. Although it symbolizes the eternity and purity of love, it often seems like a beautiful cold princess, its rigid structure making it seemingly indifferent to us. But for all their aloofness, diamonds share a human characteristic borne of our common carbon chemistry; they are attracted to fats. The mining industry takes advantage of this, using grease tables to capture diamonds. Given our modern obsession with weight, diamonds could become a new symbol for those longing to be liberated from the tyranny of diets, the strap line ‘diamonds are for blubber’ might do the trick.