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414 results on '"Mitsuishi, Masaya"'

5. Preparation of polycyclosiloxane/ZnO nanoparticle hybrid ultrathin films by Layer-by-Layer assembly methods.

Author

Zhou, Qian, Zhu, Huie, and Mitsuishi, Masaya

Subjects
THIN films, ATOMIC force microscopy, OPTOELECTRONIC devices, BILAYERS (Solid state physics), NANOPARTICLES
Abstract

Layer-by-layer (LbL) assembly methods through alternative dipping processes were used to prepare hybrid nanoassemblies of 5 nm ZnO nanoparticles (ZnONPs) with catechol-functionalized polycyclosiloxane (CFPS60, 51.9 mol% catechol content). ZnONPs were assembled on solid substrates regularly and firmly through interactions with 4 nm-thick CFPS60, proved using UV-vis absorption measurements, atomic force microscopy and peel-off test. ZnONPs exhibited yellow photoluminescence (PL) in CFPS60/ZnONPs films, and the PL intensity increased notably as the number of bilayers increased. The work demonstrates that CFPS60 has a good hybrid nanoassembly formation capability, which is promising for next-generation optoelectronic device applications. [ABSTRACT FROM AUTHOR]

Published
2024
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27. Synthesis of Ba1-xSrxYSi2O5N and discussion based on structure analysis and DFT calculation

Author

Yasunaga, Takuya, Kobayashi, Makoto, Hongo, Kenta, Fujii, Kotaro, Yamamoto, Shunsuke, Maezono, Ryo, Yashima, Masatomo, Mitsuishi, Masaya, Kato, Hideki, and Kakihana, Masato

Subjects
Oxynitride, Computational chemistry, Novel compound, Phosphor
Abstract

Cation substitution for inorganic solid materials is a practical approach to control their functions. Here, synthesis, structure analysis, density functional theory (DFT) calculation of novel oxynitrides Ba1−xSrxYSi2O5N, and investigation of their photoluminescence properties with Eu2+- or Ce3+-activator were conducted. Single crystal and powder X-ray analyses revealed that Ba1−xSrxYSi2O5N were formed at x ≤ 0.75 and they were isotypic while the synthesis of SrYSi2O5N (x = 1) was not achieved by any synthesis conditions examined. Based on phonon calculation, it was concluded that the synthesis of SrYSi2O5N with the isostructure to BaYSi2O5N was impossible due to the thermodynamical unstability. Substitution of Ba with Sr decreased the average bond length of AE-(O,N) (AE = Ba and Sr) and increased distortion of AE sites. On the other hand, coordination environments of Y sites were rarely affected by the substitution. As a result, redshift and broadening of emission spectra for Eu-doped samples were observed, whereas there was almost no spectral change in Ce-doped samples., ファイル公開：2021-08-01

Published
2019

32. Effects of Hydride Transfer Ring-Opening Reaction on B(C6F5)3Catalyzed Polymerization of D4HCyclosiloxane and Dialkoxysilanes toward Thermally Stable Silsesquioxane–Siloxane Hybrid Materials

Author

Zhu, Huie, Hiruta, Shogo, Demirci, Ali, Kim, Soyeon, Hoshino, Norihisa, Akutagawa, Tomoyuki, and Mitsuishi, Masaya

Abstract

The Piers–Rubinsztajn (PR) reaction catalyzed by a metal-free B(C6F5)3catalyst was reported as efficient in synthesizing novel polysiloxanes through polycondensation of dialkoxylsilanes and dihydrosiloxane monomers at room temperature. This study is aimed at developing new cyclosiloxane polymers having no hydrocarbon linker in the main chain via an equimolar PR reaction between tetrafunctional eight-membered cyclosiloxanes (TMCS) having the four reactive silyl hydrides (Si–H) at the Si vertices and bifunctional dialkoxylsilanes. The final polymers were targeted with the remaining Si–H group at the Si vertices of the TMCS repeating units for post-functionalization, good solubility in typical organic solvents for post-processing, and a stable ring structure in TMCS for outstanding macromolecular flexibility. However, hydride transfer ring-opening polymerization (HTRP) of TMCS was reported in the B(C6F5)3-catalyzed reaction system, which invariably causes uncontrollable gelation. Suppression of HTRP succeeded via control of total monomer concentration and reaction time reduction, thereby obtaining post-processable and post-functionalizable liquid cyclosiloxane prepolymers. Thermal curing of the prepolymers through self-cross-linking of the remaining reactive Si–H groups gave rise to free-standing films with excellent thermal stability exceeding 600 °C and a low dielectric constant. The functional versatility of the Si–H groups produces promising prepolymers for creating various functional materials.

Published
2022
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