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757 results on '"Hayakawa, Teruaki"'

101. Preferred‐handedhelical conformation in organic–inorganic hybrid block copolymers with well‐controlledstereoregularity

Author

Kometani, Satoshi, Kato, Tomoki, Manabe, Kei, Seko, Tamio, Chang, Yu‐Ning, Luo, Huai‐Rou, Agata, Yoshihiro, Ohta, Noboru, Hayakawa, Teruaki, Fujii, Syuji, Nakamura, Yoshinobu, Li, Ming‐Chia, and Hirai, Tomoyasu

Abstract

A novel block copolymer containing polyhedral oligomeric silsesquioxanes (POSS) features a well‐controlled stereoregularity, that is, isotactic polymethacrylate‐functionalized POSS‐b‐polymethyl methacrylate (it‐PMAPOSS‐b‐PMMA), was prepared via controlled‐anionic polymerization. The stereoregularity of each segment in the it‐PMAPOSS‐b‐PMMA is evaluated using nuclear magnetic resonance (NMR) spectroscopy, which reveals an isotactic configuration in both the PMAPOSS and PMMA segments. The secondary structure of it‐PMAPOSS‐b‐PMMA in a mixture with a small chiral dopant is clarified with electronic circular dichroism and vibrational circular dichroism measurements. By adding a chiral dopant, a controlled preferential helical conformation of the unilateral segment in achiral it‐PMAPOSS‐b‐PMMA is achieved.

Published
2022
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102. Hyperbranched aromatic poly(ether ketone) functionalized with TEMPO as a heterogeneous catalyst for aerobic oxidation of alcohols

Author

Shi, Ying, Ying, Shi, Nabae, Yuta, Hayakawa, Teruaki, and KAKIMOTO, MASA-AKI

Subjects
chemistry.chemical_classification, Ketone, General Chemical Engineering, Homogeneous catalysis, Ether, General Chemistry, Heterogeneous catalysis, Catalysis, Turnover number, chemistry.chemical_compound, chemistry, Benzyl alcohol, Alcohol oxidation, Polymer chemistry, Organic chemistry
Abstract

A hyperbranched aromatic poly(ether ketone) functionalized with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO/HBPEK) was investigated as a novel heterogeneous catalyst for aerobic oxidation of alcohols. The TEMPO/HBPEK contained 2 mmol g-1 TEMPO and had a turnover number (TON) of 46 compared to commercial TEMPO with a TON of 60, indicating good catalytic activity and selectivity for the aerobic oxidation of benzyl alcohol. This material can be used as a recyclable heterogeneous catalyst by grafting it onto insoluble supports such as carbon black (TEMPO/HBPEK/CB) or polyimide nanoparticles (TEMPO/HBPEK/PI), whereas the bare TEMPO/HBPEK acts as a homogeneous catalyst. These heterogeneous catalysts had TONs of 27 and 22, respectively, indicating greater catalytic activity than the commercially available heterogeneous catalyst, TEMPO immobilized on polystyrene, which had a TON less than 1.

Published
2015
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113. Defect dynamics in directed self-assembly of block copolymers (Conference Presentation)

Author

Azuma, Tsukasa, primary, Seino, Yuriko, additional, Sato, Hironobu, additional, Kasahara, Yusuke, additional, Kodera, Katsuyoshi, additional, Miyagi, Ken, additional, Shiraishi, Masayuki, additional, Matsuki, Ryota, additional, Kosaka, Terumasa, additional, Himi, Toshiyuki, additional, Nagahara, Seiji, additional, Chandra, Alvin, additional, Nakatani, Ryuichi, additional, Hayakawa, Teruaki, additional, Yoshimoto, Kenji, additional, Omosu, Takuya, additional, and Takenaka, Mikihito, additional

Published
2018
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122. A Nitric Acid-Assisted Carbon-Catalyzed Oxidation System with Nitroxide Radical Cocatalysts as an Efficient and Green Protocol for Selective Aerobic Oxidation of Alcohols

Author

KUANG, YONGBO, Kuang, Yongbo, Rokubuichi, Hodaka, Nabae, Yuta, Hayakawa, Teruaki, and KAKIMOTO, MASA-AKI

Subjects
Nitroxide mediated radical polymerization, Chemistry, Radical, General Chemistry, Photochemistry, Catalysis, Solvent, chemistry.chemical_compound, Nitric acid, Benzyl alcohol, Alcohol oxidation, medicine, Organic chemistry, Activated carbon, medicine.drug
Abstract

The incorporation of nitroxide radicals into a nitric acid-assisted carbon-catalyzed oxidation system (NACOS) afforded a highly efficient, widely applicable, non-metallic approach for the selective aerobic oxidations of alcohols. Without any solvent, this novel protocol has the ability to oxidize various primary alcohols to their corresponding aldehydes with selectvities as high as 99% at full conversions, with only 0.1 mol% of nitroxide radicals and < 4.5 wt% of activated carbon under mild conditions (temperatures as low as 50 °C and atmospheric pressure). The performances of several stable nitroxide radicals have been compared. The effects of nitric acid concentration, activated carbon loading, and temperature have been studied for the oxidation of benzyl alcohol. The enhanced NACOS represents a greener and more efficient fundamental chemical process, due to its use of molecular oxygen as an oxidant, and its solvent-free nature.

Published
2010
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130. Synthesis and Characterization of Organosoluble Aromatic Polyimides Containing POSS in Main Chain Derived from Double-Decker-Shaped Silsesquioxane

Author

Wu, Shouming, Hayakawa, Teruaki, Kikuchi, Ryohei, Grunzinger, Stephen, KAKIMOTO, MASA-AKI, and Oikawa, Hisao

Subjects
chemistry.chemical_classification, Chemical resistance, Pyromellitic dianhydride, Materials science, Polymers and Plastics, Organic Chemistry, Macromonomer, Silsesquioxane, Inorganic Chemistry, chemistry.chemical_compound, Polycyclic compound, chemistry, Polymer chemistry, Materials Chemistry, Thermal stability, Solubility, Glass transition
Abstract

Preparation of low dielectric constant polyimides containing double-decker-shaped silsesquioxane (DDSQ) in the main chain with high molecular weights (ηinh = 0.61 dL/g) is reported. Double-decker-shaped silsesquioxane aromatic tetracarboxylic dianhydride (DDSQDA) was prepared by reaction of DDSQ aromatic diamine and pyromellitic dianhydride through functional group conversion method. The polyimides were synthesized from DDSQDA and several aromatic diamines by a one-step high temperature solution method. Introduction of DDSQ unit in polyimides endowed properties such as solubility in organic solvents, 10% weight loss temperatures (Td10) up to 570 °C in nitrogen, the glass transition temperatures (Tg) higher than 300 °C, good mechanical properties (tensile strengths of 72.3–82.1 MPa, initial modulus of 1.8–2.6 GPa, and elongation at breakage of 8.0–15.9%), transmittances over 80% at 400 nm, and a dielectric constant of 2.43 at 1 MHz. The polyimides were soluble in organic solvents such as DMAc, chloroform, ...

Published
2008
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135. Spontaneously formed high-performance charge-transport layers of organic single-crystal semiconductors on precisely synthesized insulating polymers

Author

Makita, Tatsuyuki, primary, Sasaki, Masayuki, additional, Annaka, Tatsuro, additional, Sasaki, Mari, additional, Matsui, Hiroyuki, additional, Mitsui, Chikahiko, additional, Kumagai, Shohei, additional, Watanabe, Shun, additional, Hayakawa, Teruaki, additional, Okamoto, Toshihiro, additional, and Takeya, Jun, additional

Published
2017
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136. Perpendicular Orientation Control without Interfacial Treatment of RAFT-Synthesized High-χ Block Copolymer Thin Films with Sub-10 nm Features Prepared via Thermal Annealing

Author

Nakatani, Ryuichi, primary, Takano, Hiroki, additional, Chandra, Alvin, additional, Yoshimura, Yasunari, additional, Wang, Lei, additional, Suzuki, Yoshinori, additional, Tanaka, Yuki, additional, Maeda, Rina, additional, Kihara, Naoko, additional, Minegishi, Shinya, additional, Miyagi, Ken, additional, Kasahara, Yuusuke, additional, Sato, Hironobu, additional, Seino, Yuriko, additional, Azuma, Tsukasa, additional, Yokoyama, Hideaki, additional, Ober, Christopher K., additional, and Hayakawa, Teruaki, additional

Published
2017
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