Yuya Oaki

Vivid coloration of Ethiopian opal results from the superposition of extremely weak reflections originating from a subtly defined inverse opal structure with submicron-scale periodicity.

Core/shell particles have been synthesized using a seeded dispersion/emulsion polymerization strategy, which enables the controlled deposition of a polymer shell around preformed seed particles. The seeded dispersion/emulsion polymerization developed is a versatile method toward the core/shell particles but has been so far conducted in liquid media in the presence of a colloidal stabilizer, which is required for realization of colloidal stability during polymerization. In this study, we developed solvent-free seeded dispersion polymerization without any colloidal stabilizer. Specifically, polypyrrole (PPy) shells were successfully formed on micrometer-sized cubic sodium chloride (NaCl) seed particles by solvent-free oxidative seeded dispersion polymerization of the pyrrole (Py) monomer. The Py monomer, oxidant, and NaCl seed particles were separately placed in a sealed reactor, allowing Py vapor to diffuse and polymerize selectively on the surface of the seed particles. The resulting NaCl/PPy core/shell particles exhibited a uniform morphology with a controllable PPy shell thickness depending on the polymerization time. Subsequent dissolution of the NaCl cores in water led to the formation of PPy microcapsules while preserving the original cubic geometry of the seeds. To evaluate the versatility of this method, other water-soluble salts with different shapes, including potassium chloride, magnesium chloride, calcium chloride, and aluminum chloride, were employed as alternative templates. The results demonstrated that this approach enables the fabrication of not only core/shell particles/microcapsules with cubic shapes but also those with various shapes depending on the template used.

Imaging of invisible mechanical stresses is significant in a variety of fields. A transparent 3D flexible device integrating stimuli-responsive materials enables 2D distribution imaging of compression stresses applied by 3D irregular objects.

The exfoliated nanosheets preserving multilayered structures show both intercalation and building-block capabilities. A thin film exhibiting stimulus-responsive noniridescent structural color is obtained by coating multilayered nanosheets.

Stimulus-responsive color-changing properties of layered polydiacetylene were controlled by a data-driven approach based on small experimental data. Such method can accelerate dynamic properties of functional polymer materials.

Manipulation of 2D materials is significant to advance nanoarchitectonics. Controlled coating of exfoliated nanosheets still remains a challenge because of their inhomogeneous sizes and shapes. In the present work, iridescence,...

We demonstrate the prediction of phase transition temperatures of ionic liquid crystals by the combination of a machine learning method and chemical insights.

The thinner nanosheets with higher aspect ratio provide the flat surface exhibiting the structural color originating from the interference. The thicker nanosheets with lower aspect ratio form the rough surface exhibiting hydrophobicity.

The structural design and formation processes of bundled structures consisting of c -axis-oriented fluorapatite (FA) fibers were studied to clarify the hierarchical architecture in the tooth enameloid of sharks in the Lamnidae family.