Materials Made To Measure

Until the end of the twentieth century, the discovery of new materials was a haphazard and empirical process. We do not know how silk and paper were invented in ancient China, but we can be certain that no one understood the first thing about why they have their particular and attractive properties. Copper was perhaps first smelted in the Middle East as a by-product of pigment manufacture. Even the earliest synthetic polymers and plastics-cellulose nitrate, vulcanized rubber, bakelite-were chance discoveries, whose discoverers knew next to nothing of their material's composition.

As we enter the twenty-first century, things are fundamentally different. We have an entirely different attitude to materials discovery. Serendipity will never become obsolete, for science has always depended on an element of luck coupled to a prepared mind. But materials are being not so much discovered as invented: designed for the job, their components rationally selected and assembled for specific functions. Even steels have become highly designed materials, with carefully blended compositions to suit different roles. A report by the US National Academy of Science in 1997 put it like this: "Our knowledge now gives us unprecedented control over the structure and properties of materials."

Several factors have made this possible. Materials scientists now have at their disposal a vast array of techniques for probing the most intimate structural features of materials: new microscopes that can provide images at atomic resolution, scattering methods for deducing crystal structures of the tiniest samples, spectroscopic probes which reveal the subtleties of chemical bonding. Fabrication methods permit the control of structure over a wide range of length scales. The ability to design molecules that interact and assemble in highly specific and predictable ways has had a great impact on the synthesis of molecular materials. Increases in computer power enable theorists to predict many properties of a hypothetical material-electronic, mechanical, optical-based on a knowledge of nothing more than how the atoms are arranged. A greater understanding of the mechanisms of cell biology guide the design of new materials sympathetic to the processes of life. These developments provide many handles for manipulating the material world.

At the same time (and for much the same reasons), materials science has emerged as an expanding interface between many diverse disciplines, at which there are rich seams of fundamental science to be mined. And so the discipline has been transformed from a branch of engineering to one of the mainstreams of fundamental and applied science, attracting fruitful collaboration between scientists of all persuasions.

Regardless of whether this or that material mentioned in this article proves to be a winner in the marketplace, the impact of these changes will be profound, not only in science but in daily life. The future of information technology, energy production, transportation, space technology, medical science and chemical engineering all depend to a considerable degree on the invention of new materials. These will surely be the products of exquisite planning and execution, fabrics tailored to perform feats unimaginable in traditional materials. With such capabilities at our fingertips, society will be confronted more strongly than ever with the responsibility to make wise choices about the technologies it creates.