Japanese / English

Research for creating "smart" soft materials

"Smart Gel and Organic inorganic fusion soft materials"

 Polymer gel is one of the research subjects of macromolecular science that has made rapid progress in the last 30 years. A polymer gel is defined as "a substance belonging to an intermediate state between a solid and a liquid that does not dissolve but swells while absorbing a much amount of solvent by crosslinking a polymer to form a three-dimensional network structure”. There are already many products that utilize the properties of polymer gel (liquid semi-solidification, slow release, molecular sieving ability, biocompatibility, lens function, etc.) in our lives. Regarding basic research as well, a lot of knowledge about polymer gel has been obtained by developing recent measurement methods.

 Our group is working on research on smart gels with even higher performance than conventional polymer gels, such as exhibiting high performance mechanical and optical properties that can be used for biomaterials, and sensors.

We prepare extremely stretchable hydrogels with good toughness by using polyrotaxane derivatives composed of α-cyclodextrin and polyethylene glycol as cross-linkers.
Gel exhibiting high-speed response: The part that looks black is a gel with porous structure, while the transparent part is a conventional bulk gel. In response to environmental changes such as temperature, the former reversibly changes the shape at a speed more than 1000 times faster than the latter.
Hydrogel prepared using polyrotaxane as a crosslinking: It can not be cut easily even with a cutter.

"Structural colored material"

 Structure color is a phenomenon that coloration occurs by the fine structure of the wavelength of light without using pigments or dyes. Traditionally, "structural color" is described as "bright color with angle-dependence observed from material whose refractive index is periodically changed with the wavelength size of visible light".

 Our group made discovery that overturn this traditional explanation;

 structural colors do not always show angle-dependence in some cases. We found that a system with a short-range order in the refractive index change displays a structural color without angle-dependence.
 Structural colored materials can be prepared from safe and inexpensive materials and become nonfading, so we are considering application as new coloring materials.

When pores of the wavelength size of the light are prepared into the polymer gel, the gel displays different colors according to its size.
When colloidal particles are dispersed in a polymer gel, the gel displays the structural color. According to the flexible movement of the polymer gel, its color changes like a rainbow.
Japanese style painting drawn using white and black fine particles: Various colors will be obtained if the size of the fine particles is changed.
Structural color of aggregated monodisperse gel particles: By changing the concentration and the average distance between gel particles, the wavelength of light showing coherent scattering changes, so the appearance of the color also changes.

"Functional organic inorganic fusion colloidal particle"

 Particles with a diameter of about 1 nm to 1 μm are called colloidal particles.

 Our group is working on research on functional organic inorganic fusion colloidal particles exhibiting optical function, environmental response, molecular recognition and so on.

Photonic Ball: Particles exhibiting optical function formed by aggregation of colloidal particles of uniform particle size
Core-shell type fine particles in which polymers with uniform molecular weights are formed in a brush shape with inorganic fine particles as the core: Change particle size and adsorption ability according to environmental changes.
Colloidal particles (Janus particle) formed from two different components: This Janus particle shows the property of rotating in response to a magnetic field.
Mold in which pores for preparing various microparticles are connected: By connecting the three adjacent holes, the solution can be permeated for tuning the particles.

"Bio-inspired material"

 An artificial material that surpasses the function of a living body can be obtained by copying the structure and function of living organisms, plants, or their materials and molecules.

 Our group is working on the development of biosensors, biomechanical devices, bio-optical materials, etc. with hints on the structure and functions of living organisms by combining inorganic materials, organic materials and biomaterials.