Alan MacDiarmid, 79, Nobel-winning chemist

Alan G. MacDiarmid, 79, one of three scientists who shared the 2000 Nobel Prize in chemistry for the discovery of plastics that conducted electricity, died Wednesday at Delaware County Memorial Hospital of injuries following a fall earlier in the day at his Drexel Hill home. He had been rushing to catch a plane to fly to his native New Zealand.

Dr. MacDiarmid had been a chemistry professor at the University of Pennsylvania since 1955.

"Alan was suffering from myelodysplastic syndrome, a blood disorder like leukemia," said his wife, Gayl Gentile. "He expected to live only a few weeks and wanted to say goodbye to his brothers and sister in New Zealand."

"This is such a sad day for all of us in the Penn family," Penn president Amy Gutmann said Wednesday. "We have lost not only a great chemist and scientist of extraordinary accomplishment and global stature but also an enthusiastic friend and wonderful colleague who was modest and gracious even as he won the honor of all honors, the Nobel Prize."

Dr. MacDiarmid shared the 2000 Nobel Prize with former Penn professor Alan J. Heeger, now at the University of California at Santa Barbara, and Hideki Shirakawa, of the University of Tsukuba in Japan. The work underlying the award showed that plastics, or polymers, can be made to conduct electricity as metals do. The research was conducted at Penn in the late 1970s.

The discovery came about by chance. Shirakawa had made a form of silver-colored polymer in his lab in Tokyo. Dr. MacDiarmid and Heeger had made similar silver films using sulfur nitride at Penn. Shirakawa was invited to Penn, and the three researchers infused iodine into the polymer. Electrical conductivity in the film increased 10 times in minutes.

This research introduced an unexpected phenomenon in chemistry and unleashed advancements that led to computer screen shields, windows that exclude sunlight, light-emitting diodes (LEDs), solar cells, bright cell-phone displays, and tiny televisions. The discovery spurred other scientists to use conductive polymers to develop molecular electronics that increase the speed and reduce the size of computers.

Born in Masterton, New Zealand, Dr. MacDiarmid wrote more than 600 research papers and held more than 30 patents. He earned bachelor's and master's degrees from the University of New Zealand and doctorates from the University of Wisconsin and the University of Cambridge in England.

"Alan remained an active researcher until the day before his death," said David Pursell, head of Penn's chemistry department. "Since winning the prize, he continued his research on polymers. However, he and and other researchers were working on a Department of Energy program called the 'grand hydrogen challenge' to find ways to move from a fossil-fuel based economy to one using hydrogen."

Dr. MacDiarmid married Marian Mathieu in the early 1950s, and they raised four children in the Philadelphia region. She died in 1990. After a 14-year friendship, he married Gayl Gentile in 2005. "My father was full of energy and curiosity," said his daughter Heather McConnell. "He was demanding and had high expectations for his children."

In addition to his wife and daughter, Dr. MacDiarmid is survived by daughters Dawn Hazelett and Gail Williams; a son, Duncan; nine grandchildren; two brothers; and a sister.

A memorial service will be held at 3 p.m. March 2 on the Penn campus at Irvine Auditorium, 34th and Spruce Streets.