MacDiarmid, Alan G.

MacDiarmid, Alan G. (1927-2007), New Zealand-born American chemist and cowinner of the 2000 Nobel Prize in chemistry. MacDiarmid shared the prize with American chemist Alan J. Heeger and Japanese chemist Hideki Shirakawa for the discovery and development of so-called conducting polymers—plastics that conduct electricity. Before MacDiarmid and his colleagues made their discovery in the late 1970s, compounds such as metals and silicon were known to be electrical conductors, but no one had demonstrated conductivity in plastics and other polymers. MacDiarmid and his fellow Nobel honorees opened up a new field of research in conducting polymers. This technology is now being harnessed in the development of numerous electronic devices.

Born in 1927 in Masterton, New Zealand, MacDiarmid studied chemistry at the University of New Zealand, earning his master’s degree in 1950. He went on to earn a Ph.D. from the University of Wisconsin-Madison in 1953 and another Ph.D. from Cambridge University two years later. He joined the faculty of the University of Pennsylvania in 1955 and remained there until his death.

In the mid-1970s MacDiarmid and Heeger were examining the properties of a polymer known as sulfur nitride. They created a thin, metallic-looking film made of the substance. MacDiarmid happened to mention the film during a seminar in Japan. During a coffee break, he was approached by Shirakawa, a researcher then working at the Tokyo Institute of Technology. Shirakawa had recently created his own thin film by accident, after a graduate student in his lab mistakenly added too much catalyst to a batch of another polymer, polyacetylene.

MacDiarmid invited Shirakawa to the University of Pennsylvania, where, together with Heeger, they worked on Shirakawa’s silvery polyacetylene film. The scientists experimented with removing and adding electrons to the film, a process known as doping. After they diffused iodine into the film, they found that the polyacetlylene’s electrical conductivity shot up by a factor of 10 million. The iodine had chemically released some of the densely packed electrons in the plastic, permitting the movement of an electric current. The three scientists published their results in 1977. The work was immediately recognized as revolutionary, and a new field was born—one that today combines the efforts of scientists from diverse fields, including chemistry, physics, and electrical engineering.

Scientists have found numerous applications for conducting polymers. Some photographic films, for example, use a layer of conducting polymers to draw off static electricity that might otherwise damage the film. Research into conducting and semiconducting plastics will soon produce new displays for cellphones, computers, flat-screen TVs, and other devices. Scientists continue to pursue applications based on plastic electronics, including tiny computers in which impulses will be carried not by silicon chips but by single organic molecules.

In addition to the Nobel Prize, MacDiarmid received many other distinctions. He was awarded the British Royal Society of Chemistry Centenary Medal and Lectureship in 1983 and the Chemistry of Materials Award from the American Chemical Society in 1999.