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ResearchNano-Materials Field

Nano-Materials Coordinator: Takayoshi Sasaki

Creating new materials and eliciting novel functions by sophisticated control of compositions and structures at the nano level

Making full use of MANA’s advanced chemical synthesis technologies, beginning with soft chemistry, supermolecular chemistry and template synthesis, we are researching the creation of new nanomaterials such as nanotubes, nanowires, and nanosheets. Based on a wide range of material systems, spanning both organic and inorganic materials, we aim to discover novel physical properties and phenomena arising from size and shape in the nanometer range. MANA also develops and owns cutting-edge characterization facilities, including an integrated system of the transmission electron microscope with the scanning probe microscope, and is actively using these instruments for in-situ analysis of individual nanomaterials. In addition, we are promoting chemical nano- and mesoarchitectonics, in which these nanomaterials are precisely arranged, integrated and hybridized in the nano-to-meso range. By constructing artificial nanostructured materials in a designed manner, our aim is to create new materials that will exhibit advanced, innovative functions, and contribute to progress in a wide range of technological fields, including electronics, energy and the environment.

Creating two-dimensional nanomaterials (nanosheets)

MANA has synthesized two-dimensional oxide and hydroxide nanosheets as a graphene analogue by delaminating layered crystals into single layers in a solution, after inducing them to swell by more than 100 times. High grade nanosheets with diverse electronic, magnetic, optical and chemical functions were created this way with precise control of the composition, structure, and thickness and width dimensions. Development of new materials that demonstrate novel functions, is progressing via soft-chemical nanoarchitectonics, in which these nanosheets are assembled and hybridized layer by layer.

(Left) Crystals displaying huge hydration swelling
(Right) delaminated titanium oxide nanosheets

Creating nanoporous materials with highly crystallized frameworks

Focusing on porous substances that have a large surface area (i.e., nanoporous materials), and particularly on nanoporous materials with high crystallinity skeletons, MANA is developing applications of these materials as adsorbents, catalysts, catalyst carriers, sensor materials, and etc. It is doing so by utilizing amphiphilic molecules, such as surfactants and block copolymers. MANA is also extending the framework compositions to metals by electrochemical processes, and has developed synthesis techniques that are applicable to all metals. The high electrical conductivity of the framework of metallic nanoporous materials is expected to lead to new applications in the electrochemical field, which are not possible with the existing porous materials.

Synthesis of metallic nanoporous material using the micelle assembly method (metal ions are coordinated in a diblock copolymer micelle consisting of polystyrene-polyethylene oxide (PS-PEO), and the metal ions are reduced on the micelles by electrodeposition)

Creating supermolecules that can detect designated substances

Detection and capture of a designated object by a molecule is the action of a “supermolecule.” We developed the new molecule “Cesium Green” (below left), which coils around a cesium ion and emits green fluorescent light. Because this molecule was designed to precisely match the size of the cesium ion, it only causes fluorescence of cesium ions (for example, fluorescence does not occur in the case of sodium and potassium ions). The location of cesium ions in plant cells can be identified by this fluorescence (below right). By using the principle of the supermolecule, it is also possible to detect various important substances, such as amino acids and drugs.

(Left) Capture of cesium ion (green)
(Right) Visualization in a plant cell (cesium is concentrated in the part that displays green fluorescence)

Pioneering techniques for nanoscale property analysis using a high resolution transmission electron microscope

We are developing pioneering in-situ techniques for measuring nanotube, nanowire and nanosheet properties by combining the highest spatial, energy and temporal resolutions peculiar to the HRTEM with the unique possibilities created by precise manipulations of an individual nanoobject. Such techniques involve its manipulating, electrical biasing, resistive heating, charging, bending, stretching, peeling, and illuminating with light of various wavelengths and pulse frequencies under continuous control of all electromechanical, thermal and optoelectronic parameters. Ultimately, we can establish an unambiguous structure-property relationship, shining a new light on prospects for any nanomaterial applications.

A general setup inside the HRTEM for in-tandem imaging and probing an individual nanomaterial with an STM-tip (electrical property analysis), AFM-cantilever (mechanical property analysis) and light (optoelectronic/photovoltaic property analysis)