| Major Research Areas：Polymer Chemistry, Functional
Polymers, Molecular Devices |
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SHINOHARA Laboratory
Direct Observation of Single-Molecules
in π-Conjugated Polymers
Discovery of Principles and Flexible Functions
beyond Proteins |
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Research activity |
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Fundamental
chemistry of single-molecules in π- conjugated polymers
Polymers are very useful materials that display many
excellent properties, and they have become indispensable in
maintaining and developing our current way of life. In particular, π-
conjugated polymers are recognised as being part of the nextgeneration
of functional polymers for optical and electronic
applications. Nevertheless it is difficult to discuss the correlation
between their structures and functions on the molecular level,
since these are diverse, dynamic and can be very complex. If the
structure and functions of a polymer could be directly observed,
with minimal inferences or hypotheses, the relationship between
polymer structures and functions could be clarified. Consequently,
molecular devices of a polymer might be created based on new
design concepts and new working principles.
To date, we have mainly conducted the following studies.
First, we imaged the higher-order structure of a single molecule of
a chiral helical π-conjugated polymer. To be more precise, we
elucidated the higher-order structure by directly measuring the
main-chain chiral right-handed helical structure on a nanometer
scale using a scanning tunneling microscope (STM). Second, we
discovered a new phenomenon, which is that the fluorescent
emission color of a single polymer molecule changes on the order
of seconds. This was achieved by directly observing the dynamic
function of photon emission based on the thermal fluctuation of a
single molecule of fluorescent π-conjugated polymer, using a total
internal reflection fluorescence microscope (TIRFM), which we
developed. In addition, we simultaneously imaged the structure
and function of a fluorescent π-conjugated polymer. This was
achieved using a combination of an AFM and an objective-type
TIRFM. This new microscope can observe long-distance optical
communication on the order of micrometers, and is based on the
interaction of a nano structure of a π-conjugated polymer and
photons in the near-field. We also discovered a long periodic
structure of a single molecule of a chiral helical π-conjugated
polymer using an AFM. We then verified that each polymer chain
has distinctive features and simultaneously elucidated its diversity.
Afterwards, we achieved a high-speed AFM image of the random
movement of a single π-conjugated polymer chain in a solution at
room temperature. Based on an analysis, we have demonstrated
that movement, which complies with Einstein’s Law of Brownian
Motion, is based on thermal energy.
Thus, we have developed a science to elucidate the essence of single molecules
of π-conjugated polymer in a flexible and innovative manner, without the constrictions of the existing
academic framework. We anticipate that our studies will be the
basis for creating innovative molecular devices such as molecular
motors or molecular electronics/photonics materials that utilize
thermal energy as a driving source. |
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■Equipment
Polymer Synthesizer, Nuclear Magnetic Resonance Spectrometer
(NMR), Scanning Probe Microscope (STM, AFM), Near-field
Optical Microscope |
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| Voice |
Take on the challenge of unique research that nobody has ever
tried before!
Our research is at the frontier of polymer chemistry! |
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| The main research achievements in the past five years |
| 1: |
K. Shinohara, New Development of Surface Treatments for Polymers
Chapter 2-2, CMC Press (Tokyo) ISBN 978-4-88231-659-6 in press (2007). |
| 2: |
K. Shinohara, T. Suzuki, T. Kitami, and S. Yamaguchi, Simultaneous
Imaging of Structure and Fluorescence of a Supramolecular Nanostructure formed
by a Coupling of π-Conjugated Polymer Chains in the Intermolecular Interaction,
J. Polym. Sci. Part A: Polym. Chem. 44, 801-809 (2006). |
| 3: |
K. Shinohara, Award for Young Scientist Lecture, Society
of Polymer Science, Japan and the Kansai Region Branch (2005). |
| 4: |
K. Shinohara, Single Macromolecular Science, Society of Polymer
Science, Japan Ed., pp 1-32, NTS (Tokyo) ISBN 4-86043-076-X (2005). |
| 5: |
K. Shinohara, T. Kitami, and K. Nakamae, Direct Measurement
of a Structural Diversity in Single Molecules of a Chiral Helical π-Conjugated
Polymer, J. Polym. Sci. Part A: Polym. Chem. 42, 3930-3935 (2004). |
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