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Showing 101–114 of 114 results
Advanced filters: Author: Yasuhito Suzuki Clear advanced filters

  • Poly[2]rotaxane and graft polyrotaxane were synthesized from a mixture of poly(crown ether) as a trunk polymer, boronic-acid-terminated secondary ammonium salt as an axle component and diol as an end-capping group by pseudorotaxane formation and subsequent catalyst-free dehydrative bondage between the boronic acid and the diol moieties. It turned out that the chemical stability of these supramolecular architectures primarily depends on the bulkiness of the diol group as the end-capping moiety and the inherence originating from the dynamic covalent bond of boronate.

    • Yasuhito Koyama
    • Yudai Suzuki
    • Toshikazu Takata
    Reviews
    Polymer Journal
    Volume: 44, P: 30-37

  • As porous polymer materials with continuous epoxy skeletons and pores, epoxy monoliths exhibit unique mechanical properties and fracture behavior different from the bulk thermoset of epoxy resins. In this article, we describe the thermal properties, pore structures, and mechanical properties of epoxy resins with tensile and compressive deformation of the monoliths. In addition, a change in the inner porous structure after large deformation was nondestructively observed by X-ray CT imaging.

    • Kazuma Aragishi
    • Yoshihiro Takeda
    • Akikazu Matsumoto
    Research
    Polymer Journal
    Volume: 56, P: 529-540

  • During bulk polymerization, the relative concentration of monomer and polymer changes. When the monomer is liquid and the obtained polymer is a glassy solid, vitrification occurs at some point of the reaction. Herein, we investigate the bulk polymerization of methyl methacrylate, ethyl methacrylate, and butyl methacrylate. We show that, at the vicinity of vitrification, the reaction solution becomes heterogeneous, which results in an apparent phase separation. We discuss polymerization-induced vitrification in conjunction with reaction acceleration (the Trommsdorff effect) and subsequent deceleration (the glass effect).

    • Yasuhito Suzuki
    • Ryutaro Mishima
    • Akikazu Matsumoto
    Research
    Polymer Journal
    Volume: 55, P: 229-238

  • Thermal curing of maleimidobenzoxazines (MB-Rs) with n-butyl, 2-ethylhexyl, allyl, and phenyl substituents was carried out in the presence of tetrafunctional thiols with pentaerythritol and glycolurea cores. The thermosets were prepared by the following curing processes: directly curing the mixtures at 140–160 °C and postcuring the building block. The effects of the network polymer structures on the thermal stability and mechanical properties of the thermosets were investigated. The thermosets showed excellent decomposition temperatures, i.e., Td5 = 215–309 °C and Td50 = 318–587 °C. The mechanical properties were modified by introducing a 2-ethylhexyl group, and stretchable and bendable thermosets were obtained.

    • Minako Takasu
    • Kanta Sugiura
    • Akikazu Matsumoto
    Research
    Polymer Journal
    Volume: 56, P: 17-30

  • Radical copolymerization of lithium p-styrenesulfonate (LiSS) was investigated using acrylamide (AAm) as the comonomer in the presence of various salts as additives. The addition of lithium chloride promoted the polymerization reactivity of LiSS, while the addition of lithium bromide and sodium bromide suppressed the copolymerization of LiSS and AAm and completely prevented the spontaneous homopolymerization of AAm. The interactions between lithium cations and functional groups in the monomers and polymers that benefit the copolymerization reactivity is discussed.

    • Haruki Uesaka
    • Yasuhito Suzuki
    • Akikazu Matsumoto
    Research
    Polymer Journal
    Volume: 55, P: 1057-1066

  • We performed cationic ring-opening polycondensation of a galactose-based cyclic sulfite monomer to give (1 → 2)-galactan. Treatment of the cyclic sulfite with 10-(+)-camphorsulfonic acid (CSA) in the presence of water initiated ring-opening polycondensation to give benzylated (1 → 2)-galactan. The MALDI-TOF mass spectrum of the obtained polymer showed a simple pattern with even intervals, indicating the formation of benzylated (1 → 2)-galactan with OH termini. When we used 4-penten-1-ol as the alcohol initiator for cationic polycondensation, we obtained a pentenoyl group-terminated polymer and/or cyclic oligosaccharides. The mechanism for the polycondensation reaction was determine through systematic investigations of the polymerization and DOSY spectral measurements of the polymer. The present method may be useful with graft polymerizations designed to give oligogalactan-containing glycosides in one pot.

    • Ryo Miyazaki
    • Misaki Suzuki
    • Yasuhito Koyama
    Research
    Polymer Journal
    Volume: 55, P: 213-221

  • Joana Carlevaro-Fita, Andrés Lanzós et al. present the Cancer LncRNA Census (CLC), a manually curated dataset of 122 long noncoding RNAs (lncRNAs) with experimentally-validated functions in cancer based on data from the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium. CLC lncRNAs have unique gene features, and a number display evidence for cancer-driving functions that are conserved from humans to mice.

    • Joana Carlevaro-Fita
    • Andrés Lanzós
    • Christian von Mering
    ResearchOpen Access
    Communications Biology
    Volume: 3, P: 1-16

  • We carried out the conventional radical polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization of di(1-adamantyl) fumarate, bis(3,5-dimethyl-1-adamantyl) fumarate, 1-adamantyl isopropyl fumarate, and 3,5-dimethyl-1-adamantyl isopropyl fumarate. Triblock copolymers consisting of rigid and flexible segments were synthesized by the RAFT polymerization of 2-ethylhexyl acrylate using poly(dialkyl fumarate)s as the macro-chain transfer agents. The excellent thermal stability of the adamantane-containing poly(dialkyl fumarate)s was confirmed by thermogravimetric analysis. The alignment of the rigid poly(dialkyl fumarate)s chains in the solid-state was revealed by X-ray diffraction.

    • Nagisa Tsuji
    • Yasuhito Suzuki
    • Akikazu Matsumoto
    Research
    Polymer Journal
    Volume: 51, P: 1147-1161

  • The relaxation behavior of random copolymers of diisopropyl fumarate (DiPF) with 1-adamantyl acrylate (AdA) and n-butyl acrylate with various compositions was investigated using dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The β relaxation temperature systematically shifted depending on the glass transition temperature of the counterpart copolymers, and the merging of the α and β processes at an intermediate composition was also observed. Thus, the random copolymerization of DiPF and acrylates enables us to fine tune the properties associated with the β relaxation of DiPF segments.

    • Yasuhito Suzuki
    • Tomoya Tsujimura
    • Akikazu Matsumoto
    Research
    Polymer Journal
    Volume: 51, P: 1163-1172