Worldwide R&D

Laboratory Profile: Development of a Photoinduced Molecule System
Seki Laboratory, Graduate School of Engineering, Nagoya University
Seki Laboratory was established in July 2002 byProfessor Takahiro Seki, formerly of the ChemicalResources Laboratory at the Tokyo Institute ofTechnology. Assistant Professor Shusaku Nagano joined
our laboratory in November 2002. Our laboratory has
now been conducting research for a year after theenrollment of students in April 2003. Associate Professor
Yukikazu Takeoka joined us in April 2004, and we are now
pursuing our research interests with a total of 25
members: three supervisors, a secretary, a JSPS
Postdoctoral Fellow, five PhD students, ten masters
course students and five undergraduate students.
Our principal topic of research involves developing
assembly methods for new soft materials having
photoresponsive functions, such as organic polymer films,
liquid crystals, colloidal materials, and compounds thereof,and controlling dynamic functions of these materials.
Professor Seki has been particularly interested in
conducting research on monomolecular film withnanometer thickness in order to verify that the film
provides useful photoresponsive properties. Azobenzenemolecules reversibly change molecular shape and otherproperties in response to light. Professor Seki has
incorporated these molecules in high polymers toconstruct molecular systems in which photoresponsive
information at the molecular-level can be effectively
conveyed to and amplified at the material level. While
much research has been conducted on the manipulation ofelectrons, holes and optical information using light, ourresearch is distinguished by our efforts to realize dynamic
functions in molecules or the material itself that exhibit
photoinduced motion, such as expansion and contraction ,migration, or molecular alignment. We discovered aphotoresponsive monomolecular film that exhibits theworld's largest level of expansion and contraction, as wellas the most sensitive photoinduced mass transfer. Inaddition, we succeeded in developing a new techniqueusing light to align polymer films and mesoporous
inorganic material. The diagram shows the concept of ourresearch. Our focus is not on the behavior of a single
molecule, but on the strong molecular cooperativity(interaction) exhibited when an aggregation of molecules
and high polymers behave as a group. The concept ofdriving molecular systems with light can easily be applied
to micromachine technology.
Assistant Professor Nagano has been studying a new
approach using the Langmuir-Blodgett (LB) method toform a nanofilm on the surface of water. He developed atechnique to create a monomolecular film on the water
surface with completely hydrophobic polymers byhybridizing polar liquid crystal molecules. Since LB thinfilms normally require a polar group in the polymer for
fabrication, usable materials are limited. With thetechnique developed by Nagano, however, LB thin films
can be fabricated from many hydrophobic (non-polar)
polymers. Accordingly, his technique has attracted a lotof attention as a potential new method for fabricating
nano-materials. Nagano has also focused on block
copolymers and using light to control their twodimensional nano-scale phase separation.
Associate Professor Takeoka, who transferred fromthe School of Engineering at Yokohama National
University in April, specialized in providing functions topolymer gels. He prepares a hydrogel material using
crystals composed of molecules having uniform particle
size as a genetic template. The hydrogel selectivelyreflects incident rays to emit various colors based on its
periodic structure. The wavelength of reflected lightvaries because the hydrogel expands and shrinks inresponse to such stimuli as temperature, pH, light, andenzyme activity , causing changes to the periodicstructure distance. Accordingly, the hydrogel can be used
as a sensor for reflecting various responses to theenvironment. There is also much interest in employing
this gel for directly observing cooperative movement ofpolymer chains.
Our laboratory has been actively working with otherresearch groups in the field of soft materials, focusing on
liquid crystals, gels, and nanofilms. We are committed tocontinuing studies aimed at developing a system to drive
photoresponsive molecules that will be directly useful inpractical applications.

Seki Laboratory Website:
http://www.apchem.nagoyau.ac.jp/butsu3/sekilabo/index.html
MICROMACHINE No. 47
MICROMACHINE is published quarterly by Micromachine Center (MMC) to promote the international exchange of
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