Education International, Vol. 3, No. 1, AN-5, Published July 18,
youth of the World who aspire to a career in chemistry
from Nobel Laureates to Young People (3)
Professor Hideki Shirakawa, 2000 Nobel Prize
interview with Prof. Hideki Shirakawa (pictured left) by
Prof Y. Takeuchi (right) and Prof. M.M. Ito was carried
out at Prof. Shirakawa's office, in the General Council
for Science and Technology in March, 2002.
The Committee on Chemistry Education (CCE) of IUPAC edits and
issues an electronic journal, Chemical Education International
(CEI). For the benefit of those who aspire to a career in
chemistry, each issue contains a short interview with a Nobel
Laureate in chemistry. In this way, we hope to provide
a profile of those who are at the forefront of chemistry and
give aspiring chemists role models for their future endeavors.
The intended readership of the interviews published in CEI
are senior high school students who are at a point in their
life where they must make decisions about their future career,
or first year university students in science and technology
who must begin to specialize in a chosen field of study.
We are extremely grateful to Prof. Shirakawa for his appreciation
of the idea of this series of interviews and for kindly sparing
us his precious time for the interview.
(S): Prof. Hideki Shirakawa
(CEI): Yoshito Takeuchi (Member, CCE), Masato M. Ito (Editor,
CEI: Professor Shirakawa, we would like to express our
sincere thanks to you for sparing us your time for this interview.
We understand that you are extremely busy.
The first thing we would like to ask you is how and when you became
interested in science, and in chemistry in particular, and made
up your mind to become a chemist.
S: I was asked much the same question several times when I received the Nobel
Prize. In fact I have given several different replies, and now
I feel that there is not a single definite answer. I have but
a dim remembrance of those early days. When I was a junior
high school student, I played outdoors most of the time; I collected
insect specimens and gathered flowers and herbs. In a word, I
was a boy who loved Nature. Perhaps, by having such a way
of life, I gradually began to be impressed by the wonders of Nature.
This feeling, to explore more deeply the wonders of Nature, must
have been my motivation to become a scientist.
We learned from a newspaper article that you contributed an
essay to a collection put together by students of your year
in commemoration of your graduation from junior high school.
In that essay you explained that your intention was to become
a scientist, adding that your interest was in plastics. Does
that mean that you were interested not only in Nature but also
Certainly, plastics are artificial and not a part of Nature.
A combination of plastics and insects may seem a little
unusual. However, plastic was a new invention which appeared
when I was a child, and also it was very appealing. Most popular
plastics at that time were polyvinyl chloride; nylon was also
getting popular. My mother used to wrap my lunchbox with
a Japanese wrapping cloth made of poly(vinyl chloride) (PVC)
which was a popular item at that time. This Japanese wrapping
cloth made of PVC was soft and flexible when warm, but it became
stiff when the temperature dropped. When the lunchbox
cooled down, the wrapping cloth tended to stiffen, keeping the
shape of the lunch box. I thought it was rather clumsy and felt
that there remained room for improvement of PVC.
Please tell us about the time when you were of senior high school
age. Were you still able to indulge everyday in your love of
Well, there might have been some changes as compared with my junior
high school days. I got involved in assembling a complete radio
unit from its individual parts using just a soldering iron and
a screw driver. It was a time when electronics engineering
was developing rapidly, and the items I used underwent quantum
changes; from the vacuum tube to the diode, and from there to
the transistor. It was great fun. Throughout my junior and
senior high school days, it can be said that I was interested
in three fields: using today s vocabulary they were life
sciences or biotechnology, polymer chemistry, and electronics.
Perhaps I felt that I would be happy if I could major in one of
CEI: We wonder if, during your junior and senior
high school days, there was a teacher who influenced you in
your choice of science for your future career.
S: Yes indeed; a female teacher. She taught science, though
she was not in charge of our class. I was a member of
my school s Science Club, which was an extracurricular activity
in which we could participate. The school was kind enough to
open the science laboratory for the Club so that we could do
many interesting experiments which were beyond the boundaries
of the curriculum. My teacher sometimes invited us to her house
and gave us interesting talks. I can say that she fostered
my interest in science and in chemistry in particular.
CEI: Had you already made up your mind to major in polymer
chemistry when you entered the university?
S: Not necessarily. I entered Tokyo Institute of Technology
(TIT), which at that time had only one faculty, the Faculty
of Science and Engineering. We did not belong to any single
department when we entered the university. The rule was that,
on entering third year, we were to choose a department that
specialized in the research area we wished to study. There was
no possibility left for me to be a biologist, so I had to choose
from one of two remaining options: polymer science or electronics.
Eventually I chose polymer science.
CEI: Prof. Shirakawa, would you tell us a little about your
college life, including how you came to make the choice of doing
research on polymer science?
S: Well, I was very happy when I entered the University now
that I could study my favorite chemistry as much as I liked.
At the same time my love of Nature, which stemmed back to my
childhood, was growing, and in making up my mind to pursue mountaineering
in earnest, I joined the University Mountaineering Club. This
cost me a lot of money in travel expenses etc, so I did some
tutoring to earn some money. The trouble was that this took
up much of my time. Then, a friend of mine brought some good
news. According to him, one of the professors who studied the
physical properties of polymers was recruiting a laboratory
assistant. I jumped at this possibility. I really needed the
money, but this was not the only positive; even if I was only
a mere assistant, it was really interesting for me to be able
to do experiments at a research level.
CEI: What kind of experiments did you do as an assistant?
S: My employer was Dr. Ichitaro Uematsu who was at the time
an instructor who belonged to the laboratory of Prof. Kisou
Kanamaru, a physical chemist specializing in polymers. Dr. Uematsu
was involved in measuring the physical properties of a solid
material which was prepared from stereoregular polypropylene,
which was newly prepared on trial by high temperature/high pressure
molding. My job was to prepare specimens whose physical
properties were to be measured.
CEI: How did you like the job?
S: The procedure itself was simple. I just measured out
a certain amount of powdered polypropylene, put this into a
medal molder, heated it up to a predetermined temperature and
molded it by applying high pressure. It was stimulating, however,
to be surrounded by many sophisticated pieces of apparatus in
the laboratory. I liked the atmosphere of a research laboratory,
which was something that could not be experienced in the undergraduate
CEI: That experience was before you started your experiments
for the graduation thesis?
S: Yes, indeed. At the latter stage of the 3rd
year, the largest concern for students was the choice of the
professor who would supervise their studies for the graduation
thesis. Soon after I entered TIT, I became interested in studying
the synthesis of polymers, and I wanted to be supervised by
a particular professor in this field, namely by Professor Shu
Kambara. At that time there was a regulation that the
maximum number of students that could be supervised in the graduation
work by one professor should be six. Unfortunately more than
six students applied for Prof. Kambara s laboratory. We students
discussed, and decided that the selection should be made by
tossing a coin. Regrettably enough, I was one who lost the contest.
CEI: Life is hard, indeed! How did you get over the problem?
S: Other laboratories specicalizing the synthesis of polymers
had already filled their student quotas, and the only remaining
possibility was to belong to Prof. Kanamaru s laboratory. Prof.
Kanamaru was a physical chemist of polymers, and was well known
as the most severe professor in the Department. There was no
room for choice, and I became a member of the Kanamaru laboratory.
By coincidence, Dr. Uematsu directly supervised me during the
graduation study. At the beginning of my graduation study, it
was difficult for me to get used to studying the physical properties
of polymers, and sometimes I failed to find the motivation to
study hard. But gradually I became interested in the physical
chemistry of polymers and perhaps even began to appreciate it,
at least to some extent.
CEI: So you completed your graduation study and then entered
into the Graduate School. In Japan it is usual for a graduate
student to be in the same laboratory where one completes the
S: This was not the case with me. Although I did not realize
the situation when I started my graduation study, Prof. Kanamaru
was leaving TIT because of age limit regulations at the same
time as I completed my graduation study. So if I wanted to enroll
as a graduate student, I had to find another supervisor.
Prof. Kanamaru seemed to understand the situation, and he also
knew that I wanted to be a synthetic polymer chemist. One day
Prof. Kanamaru advised me to call on Prof. Kambara to pay my
respects, and I did so. Later it turned out that that visit
was nothing but an interview as a part of the entrance examination
for the Graduate School. So, from the following April I became
a member of the Kambara Laboratory, and I was very happy to
finally become a synthetic polymer chemist. One year in the
physical chemistry laboratory may be regarded as a kind of diversion;
however that single year studying the physical chemistry of
polymers seemed to widen my scope in research. Success in the
synthesis of a compound is not the end of the research. The
structural study of synthesized polymers, for instance the relation
between the structure of the polymer and its physical properties,
would become a new target. Thus, this experience in physical
chemistry would prove to be very useful later in my career,
particularly when I was studying polyacetylene.
CEI: Please proceed then to the crucial part; your progress
starting from the beginning of your career to your ultimate
success in being awarded the Nobel Prize.
S: The theme of my research was to clarify the mechanism of
the reaction of polymerization of acetylene to polyacetylene.
The polymerization reactions are sometimes tricky. A minor difference
in reaction conditions sometimes produces a considerably different
product. The reaction requires the use of a catalyst,
and so we employed a catalyst called a Ziegler-Natta catalyst,
CEI: It was said that you employed too much catalyst. Was this
the case? This episode is rather popular and has been
quoted in many articles.
S: This actually happened to one of my research associates
who wanted to gain some experience in the synthesis of polyacetylene.
I taught him the procedure, but by mistake he used too much
catalyst. The required concentration of the catalyst is
normally in the order of mmol/liter, but he used the catalyst
in a concentration as high as mol/liter; 1000 times more concentrated!
Previously we obtained only a pulverulent body. That time we
obtained a film. We guessed that the reaction took place
too rapidly and made a film on the surface of the catalyst solution
because the quantity of the catalyst was excessive. Anyway,
a black film was obtained.
CEI: Serendipity has often been referred to in connection with
your discovery. When you saw the film for the first time, did
some anticipation of a great discovery flash through your mind?
S: No, not at all. At least not at that time. I vividly remember,
however, that obtaining the film pleased me very much because
I realized that now I could determine the infrared spectra of
the polymer. At that time we were investigating the mechanism
of the polymerization reaction of acetylene, and I wanted to
examine the structure of the double bond in the polymer.
In polyacetylenes, the single bond and the double bond (note:
originally triple bond) are linked alternatively in the polyacetylene.
There are two ways of linking two double bonds: as the s-trans
conformation and in the s-cis confirmation. In
order to know which form is involved, determination can be made
of the infrared spectrum of the polymer as a thin film. So far,
we had failed to obtain a good film. So we shouted with excitement
at this breakthrough in our research. We were a bit worried
because the film was too black. We laminated the film and determined
its infrared spectrum. There was no problem and we could measure
the spectrum. Since the spectrum looked rather simple,
I intended to make a full theoretical interpretation of all
CEI: It is rather surprising to hear the story. To a polymer
chemist such a theoretical problem of physical chemistry must
have been rather tough.
S: Perhaps I am the kind of person who would never be satisfied
unless I tried something thoroughly by myself. In addition,
I had some previous experience. During the preparation of the
thesis for my Ph. D., it became necessary to analyze the infrared
spectra of compounds I had prepared in order to elucidate their
structure. Accompanied by Dr. Noboru Yamazaki, an instructor
at that time (now he is Professor Emeritus, Tokyo Institute
of Technology), I visited Prof. Takehiko Shimanouchi at the
Department of Chemistry, Faculty of Science, the University
of Tokyo, a leading scientist in the field of infrared spectroscopy.
Prof. Shimanouchi kindly taught me the technique of vibration
spectroscopy and I could see for myself how interesting this
methodology would be to use.
I thought I should try by myself to carry out a full theoretical
interpretation of all absorptions, given that I did have some
experience in the area. I had to write a computer program
necessary for the calculations. It took many, many days. It seems
that in those days I had more time for research as I was an instructor
and had fewer responsibilities in relation to teaching and administration.
Thankfully, I was successful in being able to interpret theoretically
all the absorptions. Later, Prof. Mitsuo Tasumi, Prof. Shimanouchi
s successor and a leading scientist in infrared spectroscopy,
praised me, saying you have done a good job!
CEI: How does the story go after that?
S: Now that it was a much easier task to prepare a thin film
and determine its infrared spectrum, we polymerized acetylenes
in which deuterium or C-13 isotope were incorporated. By repeating
measurements and analyses, we found that in this polymerization
reaction, the triple bond in acetylene was cleaved to form a
cis-double bond in the polymer.
CEI: Could you feel something that would foretell your subsequent
S: Well, at that time I rather simply thought that I could
finish that research successfully now that the structure of
the polymers was elucidated. If I think back to those
days, I could say that my goal was to attempt to expand the
scope of the research.
CEI: What did these attempts include?
S: These were not necessarily unusual in their approach. It
seemed interesting to me, and probably to other chemists, to
attempt to add chlorine and bromine to the double bond of the
polymers. We thought that if we could eliminate the hydrogen
halide by heating, we would be able to obtain graphite since
the remaining structure should be carbon only. Regrettably,
that attempt was not successful.
We measured infrared spectra of the reaction product between the
polymer and the halogen. To our surprise, no signal was observed
because there was very intense absorption in all the regions measured.
(note : Virtually no infrared light transmitted through the film.
It should be pointed out that infrared light does not transmit
through a metallic film.) Anticipating that the film might
have some electric conductivity, we checked this property with
the aid of a small hand-held voltmeter to measure resistance.
The needle did not move at all. With the benefit of hindsight,
I should have used a much more sensitive instrument capable of
measuring electric resistance in the order of a gigaohm.
There was another problem. Three absorption signals could not
be interpreted properly when we measured the infrared spectrum
of the product. Later we learned about the effect of doping,
and it became possible to interpret the three signals; which were
due to the carbocation positive ion of carbon generated from polyacetylene
by removal of an electron formed by the addition of bromine. It
was possible to clarify the origin of the electrical conductivity
in this way.
CEI: Did you go to United States around that time?
S: Yes, it was at that time that I went to the United States
I thought at that time that we had come to the end of the investigation,
and so it would be timely and stimulating to go, when I received
an invitation from there. When I arrived at the University
of Pennsylvania, I explained to Professors MacDiarmid and Heeger
the story to that point in time. They suggested we should try
to measure the electric resistance of the film while exposing
it to a halogen vapor. Upon attempting this, to our surprise,
the needle underwent a large deflection.
Why was I able to obtain a very good result in the long run? Perhaps
it is because I always try keeping to and concentrating on the
one thing. The basis of my research has always been the elucidation
of the reaction mechanism of polymerization. The discovery of
conducting polyacetylene may be regarded as a logical outcome
of long-term perseverance with this research.
CEI: Thank you very much for your very interesting and stimulating
Finally, may we ask you to offer a word or two to young people
all over the world who are interested in chemistry?
S: I simply hope that they will hold communion with Nature,
and will love Nature. Everything will begin from this
love of Nature. Recently, virtual things have become
very popular. I believe, however, that opportunities to touch
real materials for yourself are very important. These
objects should not necessarily be limited to specific materials.
Living things, as well as machines and electronic circuitry,
all of these, are things to be touched by your own hands.
CEI: Thank you very much indeed.
Heeger, Alan MacDiarmid, and Hideki Shirakawa were awarded the
Nobel Prize in Chemistry in 2000 for showing how plastic can be
made to conduct electric current. This surprising discovery has
radically altered our view of plastic as a material. Conductive
polymers today constitute a growing research field of great significance
to chemists and physicists alike.
Professor Shirakawa was a faculty member of
Institute of Materials Science, University of Tsukuba for more
than 20 years. He explored an unprecedented new area of polymer
science by transforming an insulating polyacetylene to an electrically
conducting one. This achievement was often said to be
triggered by a mistake when he was a research associate in the
Chemical Resources Laboratory at Tokyo Institute of Technology a
thousandfold too much catalyst was added during the synthesis
of a polymer, resulting in a beautiful silvery film that possessed
many properties superior to metals
When Professor Alan MacDiarmid heard about the film synthesized
by Dr. Shirakawa, he invited him to become a post-doctoral fellow
the University of Pennsylvania in Philadelphia, USA. They worked
together with Dr. Alan Heeger in order to understand the mechanisms
of the appearance of conductivity in insulating polymers. They
finally came to the conclusion that it is possible to introduce
carriers in polymers by doping: modifying polyacetylene by oxidation
with halogen vapor.
In 1977, Shirakawa, Heeger, MacDiarmid, and others published
their discoveries in "Synthesis of electrically conducting
organic polymers: Halogen derivatives of polyacetylene (CH)n"
in the scientific journals. The discovery was considered a major
breakthrough in the field of polymer science. Since then, the
field has grown greatly and has also led to many new present-day
more info, visit the Nobel website