Assoc Prof Yukikazu Takeoka
Soft materials such as polymers, colloids, liquid crystals and gels exhibit interesting properties that we cannot imagine. Soft materials are used in a wide range of applications such as automobile parts and airplane parts, liquid crystal displays such as televisions and smartphones, materials for regenerative medicine, and biomaterials.
To create more sophisticated materials than traditional soft materials, we are working on the preparation of flexible, complex and smart soft materials by combining various components such as organic molecules, polymers and inorganic 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.
"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.
"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.
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.
Fumio Asai*, Takahiro Seki, Ayae Sugawara-Narutaki, Kazuhide Sato, Jérémy Odent, Olivier Coulembier, Jean-Marie Raquez, and Takeoka, Y.*;
“Tough and 3D-printable Poly(2-methoxyethyl Acrylate)-Silica Composite Elastomer with Anti-Platelet Adhesion Property”
ACS Applied Materials & Interfaces, X, X-X (2020).
Kiyofumi Katagiri,* Kensuke Uemura, Ryo Uesugi, Naoki Tarutani, Kei Inumaru, Tetsuo Uchikoshi,Takahiro Seki, and Takeoka, Y.;
“Robust Structurally Colored Coatings Composed of Colloidal Arrays Prepared by the Cathodic Electrophoretic Deposition Method with Metal Cation Additives”
ACS Applied Materials & Interfaces, 12, 36, 40768-40777 (2020).
Eiji Miwa, Kenta Watanabe, Fumio Asai, Takahiro Seki, Kenji Urayama, Jérémy Odent, Jean-Marie Raquez, and Takeoka, Y.*;
“Composite Elastomer Exhibiting a Stress-Dependent Color Change and High Toughness Prepared by Self-Assembly of Silica Particles in a Polymer Network”
ACS Applied Polymer Materials, 2, 9, 4078 -4089 (2020).
Miki Sakai, Hyunji Kim, Yusuke Arai, Takuya Teratani, Youhei Kawai, Yuichi Kuwahara, Keisuke Abe, Yasuhiro Kuwana, Katsuji Ikeda, Kazuhiko Yamada, and Takeoka, Y.*;
“Monodisperse Silica Nanoparticle−Carbon Black Composite Microspheres as Photonic Pigments”
ACS Applied Nano Materials, 3, 7047-7056 (2020).
Ryosuke Ohnuki,* Miki Sakai, Yukikazu Takeoka, and Shinya Yoshioka;
“Optical Characterization of the Photonic Ball as a Structurally Colored Pigment”
Langmuir, 36, 5579-5587 (2020).