Hideki Shirakawa, celebrated chemist and engineer, died on Aug. 24 at the age of 90.
Born in Tokyo in 1936, the future Nobel laureate was deeply influenced by living in Takayama, Japan, during most of his grade school years. The small city is surrounded by nature, where Shirakawa would collect bugs and experiment with radios, and where his pull toward science began.
“He also developed an interest in plastics as a man-made material from a young age,” says Masashi Kijima, Shirakawa’s University of Tsukuba colleague, who accompanied him to the Nobel Prize award ceremony.
“He pursued the truth behind topics that interested him and continued his research with conviction until he reached a level of understanding and satisfaction with the results.”
At lunchtime in his school days, Shirakawa noticed that the polyvinyl chloride sheet, a relatively new innovation at that time, that his mother used to wrap his hot food retained the shape of the lunchbox even after he removed it. The useful yet imperfect nature of plastics sparked his curiosity and stuck with him.
Though drawn to multiple fields, Shirakawa studied chemical engineering at the Tokyo Institute of Technology, where he focused on polymer science. In 1966, after earning his doctorate, he was hired by the institute as a laboratory assistant to study how acetylene polymerizes via the Ziegler-Natta process, a catalytic reaction.
The details are disputed, but somehow a visiting scientist working with Shirakawa produced polyacetylene as a silvery film rather than in its usual form—a dark powder. Shirakawa repeated the process until he determined that the film resulted from adding excess catalyst.
The metallic color may have spurred Shirakawa’s suspicions about the properties that the organic polymer might possess. Shirakawa didn’t let it go. According to Kijima, “He pursued the truth behind topics that interested him and continued his research with conviction until he reached a level of understanding and satisfaction with the results.”
That understanding would come later, through an interdisciplinary collaboration.
The late chemist Alan G. MacDiarmid, then a visiting professor at Kyoto University in Japan, gave a lecture at the institute about a different metallic polymer. MacDiarmid had been studying polythiazyl with physicist Alan J. Heeger at the University of Pennsylvania. Shirakawa missed the lecture, but later, while chatting and sipping green tea, they compared their golden and silvery films, and MacDiarmid ended up inviting Shirakawa to collaborate with them in Pennsylvania.
There, in 1976, Shirakawa, MacDiarmid, and Heeger found that by doping the silvery polyacetylene with bromine, they could increase its conductivity by such magnitude that it broke the electrometers they were using to probe the material’s conductivity. They had figured out a way to make plastics, widely known to be insulators, conduct electricity. The researchers published their findings in Chemical Communications, and nearly 25 years after their collaboration began, they were honored in 2000 with the Nobel Prize in Chemistry for their work. MacDiarmid later called his first meeting with Shirakawa “the most important cup of green tea I’ve ever had in my life.”
About Shirakawa’s leap of faith in moving from Japan to Pennsylvania, Heeger has said, “I thought to myself, ‘Why the hell would he do that?’ I mean, he knew MacDiarmid as an inorganic chemist and me as a physicist, but we were talking about making and studying an organic polymer that none of us had ever had any experience with. So it was courageous, and I think he was terrific.”
Shirakawa continued his work on polyacetylene after he returned to Japan, finding that partial electron transfer is what makes its conductivity possible. He joined the University of Tsukuba, where he remained until retiring as a professor emeritus in 2000, the same year he was selected as a Person of Cultural Merit in Japan.
An accomplished scientist, the laureate was also a long-term science education volunteer, helping to inspire students’ curiosity the way nature had inspired his own as a child. Known as gentle and approachable, he patiently answered every question. He personally led workshops at universities, as well as at Miraikan–the National Museum of Emerging Science and Innovation in Tokyo, where he was involved for 23 years, until his passing.
According to museum staff, Shirakawa was “constantly looking for ways to improve the workshops so that they would be easier for participants to understand and give them a greater sense of accomplishment.”
“He believed that actually conducting experiments with one’s own hands was a much better way to experience the wonder and excitement of science rather than simply listening to someone talk or looking at educational materials,” they add.
About youth education, Shirakawa has said, “When people speak of science and technology, the debate always shifts to discussions of researchers, university students, and university reform. But by these stages, it is too late. Compulsory education, meaning primary and secondary education, is also of great importance.”
Not long after winning the Nobel, he was hired by the Japanese government to craft a plan to dramatically increase the number of Nobel science laureates in the country. He later indicated that he thought the media created too much buzz about the Nobel Prize above other, nonawarded research. “Whether a prize is given or not, basic research is significant in that it satisfies human curiosity,” he stated.
Shirakawa taught his last workshop at the Miraikan museum on July 19, about a month before his death. According to Miraikan executive director Hironobu Takagi, “He was very fine at that time.”
The class description includes a message from the laureate that translates as follows: “ ‘Seeing is believing.’ However, trying an experiment once yourself allows you to experience and understand the wonders of chemistry far more than watching it a hundred times. Please take on the challenge of the mysteries of chemistry.”
Shirakawa is survived by his family and decades of students whose curiosity he sparked.
