KOBUNSHI RONBUNSHU
Online ISSN : 1881-5685
Print ISSN : 0386-2186
ISSN-L : 0386-2186
Volume 68, Issue 8
Displaying 1-7 of 7 articles from this issue
Comprehensive Papers
  • Aiichiro NAGAKI
    Article type: Comprehensive Papers
    2011 Volume 68 Issue 8 Pages 521-531
    Published: 2011
    Released on J-STAGE: August 25, 2011
    JOURNAL FREE ACCESS
    Polymerization using the characteristic features of flow microreactor systems such as fast mixing, fast heat transfer, and short residence time has attracted a great deal of attention, and extensive studies have been reported. Herein we report that the cationic polymerization of vinyl monomers can be achieved in a flow microreactor system with excellent molecular-weight distribution control without adding a capping agent, which decelerates the propagation due to the equilibrium between active and dormant species. We also report that flow microreactor systems are effective for accomplishing the controlled anionic polymerization of styrenes or alkyl methacrylates. A high level of control of the molecular weight distribution can be achieved in a flow microreactor under easily accessible conditions such as 24 to −28°C. Moreover, the efficient synthesis of well-defined polymers was successfully achieved using an integrated flow microreactor system. Diblock copolymers, triblock copolymers, and block copolymers having two different polymer chains on a silicon core were obtained with narrow molecular weight distributions.
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  • Toshimitsu KANAI
    Article type: Comprehensive Papers
    2011 Volume 68 Issue 8 Pages 532-539
    Published: 2011
    Released on J-STAGE: August 25, 2011
    JOURNAL FREE ACCESS
    Colloidal crystals, three-dimensional periodic arrays of monodisperse particles, have received considerable attention with respect to possible applications, particularly as photonic crystals. Colloidal crystals are conventionally fabricated on a substrate, and the film shape and size limits the utility of these crystals for many applications. In this comprehensive paper, a method for fabricating spherical gel-immobilized colloidal crystals using microfluidics is reported. The gel-immobilized colloidal crystal spheres or microcapsules with gel-immobilized colloidal crystal shells can be fabricated through the combination of microfluidics and photopolymerization. The diffraction color or the Bragg wavelength of the gel-immobilized colloidal crystals can be adjusted by varying the particle concentration before gelation and tuned by external stimuli after preparation. The gel-immobilized colloidal crystal shell has a higher sensitivity and wider range in the Bragg wavelength than that displayed by a bulk gel.
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  • Chikako T. NAKAZAWA
    Article type: Comprehensive Papers
    2011 Volume 68 Issue 8 Pages 540-549
    Published: 2011
    Released on J-STAGE: August 25, 2011
    JOURNAL FREE ACCESS
    There are many species of wild silkworms in the world. The silk fibroins have very different mechanical properties derived from the difference of the primary and higher-order structures. It means that the silk-like proteins designed to mimic wild silk fibroins could give rise to materials having superior properties. However, silk fibroins from wild silkworms are rarely used as materials unlike Bombyx mori silk fibroin, which is broadly used as a biomaterial. Therefore, the author focused on two kinds of wild silk fibroins, one is from Samia cynthia ricini the other is Anaphe, and produced new silk-like proteins. In this paper, the structure and mechanical properties of the two kinds of silk fibroins were outlined by comparing with those of B. mori. Furthermore, the author summarized the cell adhesion properties of those wild silk-like proteins.
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  • Takuya YAMAMOTO
    Article type: Comprehensive Papers
    2011 Volume 68 Issue 8 Pages 550-561
    Published: 2011
    Released on J-STAGE: August 25, 2011
    JOURNAL FREE ACCESS
    Cyclic polymers, possessing no chain ends, exhibit chemical and physical properties that can be distinguished from the linear counterparts. The synthesis of cyclic polymers has been pursued, and their functionalities arising from the unique shapes, namely topology effects, have been investigated. The ESA-CF process in conjunction with click chemistry selectively constructed a variety of unprecedented multicyclic topologies of polymers such as bridged- and spiro-types. It was demonstrated that cooperative electrostatic and hydrogen-bonding self-assembly followed by covalent conversion is an effective means for the synthesis of polymeric catenanes. The self-assembly of a cyclic amphiphilic block copolymer, prepared by intramolecular metathesis, gave a micelle with an approximately 50°C increase in the thermal stability in comparison with one formed from the linear precursor. Furthermore, linear and cyclic polymers containing a perylene diimide unit were synthesized, and single-molecule spectroscopy revealed the different diffusion modes of the polymers on the basis of their topology.
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  • Ken'ichiro MATSUMOTO
    Article type: Comprehensive Papers
    2011 Volume 68 Issue 8 Pages 562-569
    Published: 2011
    Released on J-STAGE: August 25, 2011
    JOURNAL FREE ACCESS
    Polyhydroxyalkanoates (PHAs) are bacterial polyesters that can be an alternative to petroleum-derived plastics. Transgenic plants harboring PHA biosynthetic genes are capable of producing PHAs directly from atmospheric CO2. The properties of PHAs greatly depend on their monomer composition. Therefore, fine regulation of monomer composition is essential to the production of PHAs with the desired properties. In order to synthesize PHA copolymer in plants, the supply of monomers and the expression of PHA synthase (polymerizing enzyme) having a broad polymerizing capacity are required. We found that the engineered enzymes with enhanced activity and/or altered substrate specificity are functional in plant cells. This finding enabled us to produce PHA copolymer in transgenic plants.
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  • Hidekazu KANO
    Article type: Comprehensive Papers
    2011 Volume 68 Issue 8 Pages 570-578
    Published: 2011
    Released on J-STAGE: August 25, 2011
    JOURNAL FREE ACCESS
    The utilization of biomass is a growing issue due to the anxiety about exhaustible resources. In the field of fibers and textiles, cellulose is one of the most suitable materials for apparel uses. Conventional cellulosic filaments such as viscose rayon and cellulose acetate are widely used in the world, but these filaments require harmful organic reagents and solvents during the production of the fibers. The aim of this study is to create new cellulosic fibers which can be manufactured by the melt spinning process. Thermo-plasticization of cellulose was examined by derivatization of cellulose. As a result of optimization of both the substituent and the degree of substitution, a cellulose mixed ester has been obtained which has excellent thermal flowability and mechanical properties of the fiber. Unlike the conventional cellulosic fibers which are manufactured by solution spinning with harmful solvents, melt spinning of the cellulose derivative of this study achieved a wide variety of the fiber cross section, ultra light fibers and ultra fine fibers.
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  • Atsuhiro FUJIMORI
    Article type: Comprehensive Papers
    2011 Volume 68 Issue 8 Pages 579-593
    Published: 2011
    Released on J-STAGE: August 25, 2011
    JOURNAL FREE ACCESS
    We developed a layered organization on the nanometer level in Langmuir-Blodgett (LB) films of several functional polymers and long-chain compounds. In the present study, the fine structures in the solid-state and molecular orientation in LB films of newly synthesized functional polymers and charge-transfer complexes were investigated by wide-angle X-ray diffraction (WAXD), small angle X-ray scattering (SAXS), surface pressure-area (π-A) isotherm, in-plane and out-of plane X-ray diffraction (XRD), and atomic force microscopy (AFM). From the results of WAXD in bulk of these compounds, formation of the sub-cell for alkyl chains were confirmed in the ab-plane. Further, these compounds form a highly ordered layer structure along the c-axis. In addition, monolayers of these compounds on the water surface are extremely condensed. Structural changes in the two-dimensional films are caused by competition between the enhancement of π-π interaction of the arranged functional groups and van der Waals interaction of long hydrocarbone chains.
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