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335 results on '"Hirai, Tomoyasu"'

3. 1H pulsed NMR measurement of reactivity of silane coupling agents for conservation of cultural heritage sites.

Author

Nakamura, Yoshinobu, Takenaka, Ayuna, Sakai, Hinari, Ikeda, Asuha, Tsuruta, Hiroaki, Yasumuro, Yoshihiro, Suemori, Kaoru, Suita, Hiroshi, Uetsuji, Yasutomo, Moriuchi‐Kawakami, Takayo, Hirai, Tomoyasu, and Fujii, Syuji

Subjects
SILANE coupling agents, HISTORIC sites, NUCLEAR magnetic resonance, METHOXY group, UNDERGROUND areas
Abstract

The network structure and reactivity of suitable restoration agent consisting of silane coupling agents (SCAs) of the brittle walls of a cultural heritage site located underground in a desert area in Egypt were investigated using 1H pulsed nuclear magnetic resonance (pulse NMR). It should possess both high coagulation strength and ductility to ensure that it can withstand an earthquake; it should also contain ethoxy rather than methoxy groups, which generate toxic methanol. The solidification rate for the SCA or oligomer with ethoxy groups was lower than those with methoxy groups; however, the final polycondensates showed the same relaxation time (hardness). The difference spectrum was developed newly to analyze the network structure combined higher strength and ductility. The distribution of crosslinking degree of such polycondensates was narrow, and the amount of lower crosslinking degree was small. On the other hand, the distribution was wide in the polycondensates with ductility but lower strength. From the compression tests of model sand solidified with the restoration agent for both methoxy and ethoxy types showed the superior properties combined higher strength and ductility. The pulse NMR experiment was useful for estimating the solidification rate and the network structure. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Chiral Transfer of Linear Polysiloxane with Preferred-Handed Helical Conformation

Author

Mure, Tomoki, primary, Kinoshita, Yakumo, additional, Sakai, Hinari, additional, Morii, Shunsuke, additional, Wu, Hsin-Ni, additional, Yung, Tsz-Ming, additional, Yu, Hao-Cheng, additional, Nagashima, Kodai, additional, Higashiguchi, Wataru, additional, Ohta, Noboru, additional, Hayakawa, Teruaki, additional, Nakamura, Yoshinobu, additional, Fujii, Syuji, additional, Li, Ming-Chia, additional, and Hirai, Tomoyasu, additional

Published
2024
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7. Nitrogen-Containing Carbon Tubes Fabricated by Light Irradiation

Author

Matsui, Kanade, primary, Yamamoto, Kenshin, additional, Oyama, Keigo, additional, Seike, Musashi, additional, Takeuchi, Kazusa, additional, Funatsu, Takahiro, additional, Mitamura, Koji, additional, Ikeda, Shingo, additional, Watase, Seiji, additional, Hirai, Tomoyasu, additional, Nakamura, Yoshinobu, additional, and Fujii, Syuji, additional

Published
2024
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10. Stimulus‐Responsive Gas Marbles as an Amphibious Carrier for Gaseous Materials.

Author

Yasui, Takanori, Fameau, Anne‐Laure, Park, Hyoungwon, Pham, Thu Thao, Pechmann, Sabrina, Christiansen, Silke, Yusa, Shin‐ichi, Hirai, Tomoyasu, Nakamura, Yoshinobu, and Fujii, Syuji

Subjects
MARBLE, CHOLESTERIC liquid crystals, TERTIARY amines, LIQUID surfaces, GASES, METHACRYLATES
Abstract

Gas marbles are a new family of particle‐stabilized soft dispersed system with a soap bubble‐like air‐in‐water‐in‐air structure. Herein, stimulus‐responsive character is successfully introduced to a gas marble system for the first time using polymer particles carrying a poly(tertiary amine methacrylate) (pKa ≈7) steric stabilizer on their surfaces as a particulate stabilizer. The gas marbles exhibited long‐term stability when transferred onto the planar surface of liquid water, provided that the solution pH of the subphase is basic and neutral. In contrast, the use of acidic solutions led to immediate disintegration of the gas marbles, resulting in release of the inner gas. The critical minimum solution pH required for long‐term gas marble stability correlates closely with the known pKa value for the poly(tertiary amine methacrylate) stabilizer. It also demonstrates amphibious motions of the gas marbles. [ABSTRACT FROM AUTHOR]

Published
2024
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14. Stringiness morphology for crosslinked polyacrylic pressure‐sensitive adhesives measured by peel testing with constant rate.

Author

Nakamura, Yoshinobu, Yoshioka, Daichi, Sato, Tomonori, Takenaka, Ayuna, Yoden, Hiroyuki, Hikasa, Shigeki, Urahama, Yoshiaki, Hirai, Tomoyasu, and Fujii, Syuji

Subjects
PRESSURE-sensitive adhesives, POLYACRYLIC acid, RANDOM copolymers, MORPHOLOGY, SURFACE tension, EQUILIBRIUM testing, ADHESIVES
Abstract

To clarify the formation mechanism of front frame‐type morphology, the stringiness of crosslinked random copolymers of poly(n‐butyl acrylate‐acrylic acid) during a 180° peel test with a constant tensile rate was examined for various crosslinker contents and rates using a quartz adherend. Cohesive failure occurred for lower crosslinker content and rate, whereas interfacial failure with sawtooth‐type stringiness without a frame was observed for higher crosslinker content and rate. Front frame‐type stringiness was formed at the boundary of cohesive and interfacial failures. To clarify the formation mechanism, observation was conducted from the start of peel test until the equilibrium state. The sawtooth‐type stringiness with branches first formed at the tip. The adjoining branches were connected and the 2D frame was formed only on the adherend surface. The formed 2D frame developed toward the 3D walls and the front frame‐type was then completed. This is caused by the surface tension that acts to restrain the increase in the surface area. However, the surface area of the front frame‐type morphology was larger than the no frame‐type. The larger absorption of peeling stress by the formation of this morphology is expected to contribute to peel strength improvement. [ABSTRACT FROM AUTHOR]

Published
2024
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25. Shape design of aqueous bubbles stabilized with millimeter-sized polymer plates.

Author

Sakurai, Yuri, Kakiuchi, Rina, Hayashi, Masaki, Hirai, Tomoyasu, Nakamura, Yoshinobu, and Fujii, Syuji

Subjects
DESIGN
Abstract

Bubbles with polyhedral morphologies were fabricated using polymer plates as a stabilizer. Precise control of the shape and size of the bubbles could be performed by tuning the size ratio of the air bubble and plate, controlling the number of plates adsorbed to the bubble, and coalescence of multiple bubbles. [ABSTRACT FROM AUTHOR]

Published
2024
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30. Photo/Thermo Dual Stimulus-Responsive Liquid Marbles Stabilized with Polypyrrole-Coated Stearic Acid Particles

Author

Tsumura, Yusuke, Oyama, Keigo, Fameau, Anne-Laure, Seike, Musashi, Ohtaka, Atsushi, Hirai, Tomoyasu, Nakamura, Yoshinobu, Fujii, Syuji, Osaka Institute of Technology = Osaka Kogyo Daigaku (OIT), Unité Matériaux et Transformations - UMR 8207 (UMET), and Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
phase-change material, [SDV.IDA]Life Sciences [q-bio]/Food engineering, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], liquid marbles, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, [SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology, General Materials Science, fatty acid, heat, light, core−shell particles, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], dual stimulus-responsive
Abstract

International audience; In this study, we report on the fabrication of photo/thermo dual stimulus-responsive liquid marbles (LMs) that can be disrupted by light irradiation and/or heating. To stabilize the LMs, we synthesized micrometer-sized stearic acid (SA) particles coated with overlayers of polypyrrole (PPy) by aqueous chemical oxidative seeded dispersion polymerization. The SA/PPy core–shell particles could adsorb at the air–water interface to stabilize LMs by rolling water droplets on the particle powder bed. The presence of SA, known as a phase-change material, which undergoes a transition from solid to liquid by heating, and PPy, which can transduce light to heat, gives rise to the photo and thermo dual stimulus-responsive characters of the LMs. The disruption of the LMs could be induced in a cascade manner: light irradiation on the LM induced a temperature increase, followed by melting of the SA component on the LM surface, leading to its disruption and release of the inner water. The disruption time is linked to the PPy loading and light irradiation power, and it can be tuned from quasi-instantaneous to a few tens of seconds. The melting of SA due to a light-induced phase change from the solid to liquid state is a new mechanism to trigger the disruption of LMs. We finally demonstrated two applications of the LMs as a light-responsive microreactor and a sensor.

Published
2022

31. Influences of probe shape and surface roughness on tack properties measured by the probe tack test and characterization of crosslinked polyacrylic pressure‐sensitive adhesives

Author

Nakamura, Yoshinobu, primary, Kishimoto, Risa, additional, Nishi, Hiroki, additional, Uchimura, Natsuki, additional, Yoden, Hiroyuki, additional, Hikasa, Shigeki, additional, Iwata, Hideki, additional, Urahama, Yoshiaki, additional, Hirai, Tomoyasu, additional, and Fujii, Syuji, additional

Published
2023
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37. Morphological and chemical stabilities of polypyrrole in aqueous media for 1 year

Author

Seike, Musashi, Asaumi, Yuta, Kawashima, Hisato, Hirai, Tomoyasu, Nakamura, Yoshinobu, and Fujii, Syuji

Abstract

The long-term morphological and chemical stabilities of polypyrrole grains in aqueous media (1-year duration) are investigated. Polypyrrole grains doped with chloride ions or heptadecafluorooctane sulfonic acid were extensively characterized using a wide range of analytical techniques. The average sizes of the grains were 13–15 μm and consisted of submicrometer-sized atypical primary particles. The grain size increased in the case of polypyrrole doped with chloride ions, whereas no apparent changes were observed in the case of polypyrrole doped with heptadecafluorooctane sulfonic acid after storage at pH 3 and 10. The size and morphology of the primary particles did not change for each grain system. Appreciable changes in chemical structure and surface chemistry were observed. At pH 10, dedoping occurred easily, and chloride ions and heptadecafluorooctane sulfonic acid were released from the grains in a short time (within one week). On the other hand, the dopants were released slowly at pH 3, which is likely caused by nucleophilic attack by water molecules to the polypyrrole. The release rate of the dopant was slower for polypyrrole doped with heptadecafluorooctane sulfonic acid than for polypyrrole doped with chloride ions. This finding is attributed due to the stronger hydrophobic interaction between polypyrrole and heptadecafluorooctane sulfonic acid.

Published
2024
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44. A Highly Conductive n-Type Coordination Complex with Thieno[3,2-b]thiophene Units: Facile Synthesis, Orientation, and Thermoelectric Properties

Author

Ueda, Kazuki, primary, Fukuzaki, Riku, additional, Ito, Takumu, additional, Toyama, Nana, additional, Muraoka, Masahiro, additional, Terao, Toshiki, additional, Manabe, Kei, additional, Hirai, Tomoyasu, additional, Wu, Ching-Ju, additional, Chuang, Shih-Ching, additional, Kawano, Shintaro, additional, and Murata, Michihisa, additional

Published
2022
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