To celebrate 70 years of advancing scientific knowledge, OSTI is featuring some of the leading scientists and works particularly relevant to the formation of DOE, OSTI, and their predecessor organizations and is highlighting Nobel laureates and other important research figures in DOE’s history. Their accomplishments were key to the evolution of the Department of Energy, and OSTI’s collections include many of their publications.
Atoms can bind together to form molecules of an innumerable variety of shapes. One basic shape characterizes polymers, whose molecules are long chains or networks of small groups of atoms, the atom groups being of just one or a few types. Many polymers are biochemical products of animal, plant, and microbial metabolism; other polymers are entirely artificial.
The different polymers are quite varied in their physical properties, but nearly all polymers discovered before the 1970s were electrical insulators. A few exceptions, though, were known to conduct electrical current. One such polymer, poly(sulfur nitride), was described by Temple University chemist Mortimer Labes in a publication that came to the attention of University of Pennsylvania physicist Alan Heeger, which got him interested in investigating that material. Knowing that his fellow professor, chemist Alan MacDiarmid, had a background in sulfur nitride chemistry, Heeger brought Labes’ paper to MacDiarmid’s attention. Heeger and MacDiarmid then began to explore this material, and later on MacDiarmid lectured about their research at the Tokyo Institute of Technology. Hideki Shirakawa, a chemist there, informed MacDiarmid of his own research group’s production of a metallically shiny (but nonconductive) form of the polymer polyacetylene. MacDiarmid then invited Shirakawa to visit the University of Pennsylvania and continue his research there. Together, Shirakawa, MacDiarmid, and Heeger found a way to make a different form of polyacetylene that could not only conduct electricity, but have its conductivity adjusted and even switched on and off by controlling the proximity of “doping” atoms that added or removed electrons from the polyacetylene molecules.
For their discovery and development of conductive polyacetylene, Heeger, MacDiarmid, and Shirakawa were awarded the 2000 Nobel Prize in Chemistry. As the news release announcing their prize explained at the time:
Conductive plastics are used in, or being developed industrially for, e.g. anti-static substances for photographic film, shields for computer screen against electromagnetic radiation and for “smart” windows (that can exclude sunlight). In addition, semi-conductive polymers have recently been developed in light-emitting diodes, solar cells and as displays in mobile telephones and mini-format television screens.
Further research, much done by others who were initially prompted by news of Heeger, MacDiarmid, and Shirakawa’s results, has in the last four decades resulted in numerous other conducting and semiconducting polymers being discovered, and the application of such polymers to devices like metal-ion batteries, transistors that can be stretched and even “healed” after overstretching, and electronics that can decompose when obsolete instead of becoming toxic waste. Some of these explorations have been funded through the U.S. Department of Energy; reports about them are available through OSTI’s SciTech Connect.
Alan MacDiarmid was born in Masterton, New Zealand in 1927. His family moved to Lower Hutt a few years later to find work during the Great Depression. Seeing one of his father’s old textbooks got MacDiarmid interested in chemistry when he was ten years old, and he began teaching himself the subject from material he found at the local public library. This interest led to his earning one bachelor’s degree, two master’s degrees, and two doctorates in New Zealand, the United States, and the United Kingdom before he was 30. In the 1950s, he became a faculty member at the University of Pennsylvania, where he concentrated on silicon chemistry research until 1977, the year he invited Shirakawa to Pennsylvania and began his work on conducting polymers. When the University of Texas at Dallas founded its NanoTech Institute, MacDiarmid became the chairman of the institute’s advisory board. The institute was renamed for MacDiarmid after his death in 2007.
Alan Heeger was born in Sioux City, Iowa in 1936. He earned a bachelor of science degree in physics and mathematics from the University of Nebraska—Lincoln in 1957 and a doctorate in physics from the University of California, Berkeley in 1961. From 1962 to 1982 he was on the faculty of the University of Pennsylvania, after which he joined the Physics Department of the University of California, Santa Barbara where he helped to found the Materials Department. Heeger also founded several startup businesses, not only for developing conducting-polymer applications but to advance other technologies, such as personalized medicine in the diagnosis and cure of cancer. As might be surmised from this variety of technologies, Heeger has changed his research focus several times. He has written that taking the long but necessary time to learn a new field well enough to be successful in it is not “an unpleasant chore[;] …the process of expanding one’s knowledge to such a high level in a new area is exciting and continues to be exciting as one proceeds through a lifetime of science.”