POLYMERS@Vol.59@No.9
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COVER STORY
Significant Advances in Polymer Gels
Growing Polymers: A Personal Account
Close Encounters of the New Kind Takeshi IKEYA
<Abstract> There are many gclose encounters of new kindsh, not only in the field of research but also in many other fields. Maintaining your interest in those gclose encountersh and playing an active role within them, you can open up a new world.
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The Similarity between Comedy and Research Takeru IWAMURA
<Abstract> I describe the similarity between comedy and research in my academic research life.
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COVER STORY: Highlight Reviews
Ionic Liquid as Solvent for Polymer Gel: Design, Characteristics, and Development of Ion-Gel Takeshi UEKI and Masayoshi WATANABE
<Abstract> We present design, characteristics, and development of polymer gels (ion-gels) swollen by ionic liquids (ILs) as solvent. ILs are room temperature molten salts and have attracted much attention because of their unique properties such as non-volatility, non-flammability, and thermal and (electro) chemical stability. We have demonstrated that ILs exhibit a variety of solubility toward polymers. Compatible combinations of polymers and ILs provide ion-gels that exhibit fast ion-transport properties. For instance, poly(methyl methacrylate) (PMMA) is completely compatible with 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfone)amide, which is a typical hydrophobic IL. Interestingly, the ion conduction in PMMA networks was found to be decoupled from segmental motion of the polymer matrix. In addition, we deal with protic IL and sulfonated polyimide composites as electrolyte membrane for fuel cells, which can successfully operate at temperatures higher than 100 under non-humidified conditions. Finally, we introduce the unique phase behaviors of polymers and polymer gels in ILs.
Keywords: Ionic Liquid / Ion-Gel / Fuel Cell / Nano-Gel / Volume Phase Transition / Block Copolymer / Structural Color / Colloid
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Structures of High Strength Polymer Gels Revealed by Small-angle Neutron Scattering Mitsuhiro SHIBAYAMA
<Abstract> Various types of tough polymer gels capable of high recoverable deformability and/or with high shear/compressive moduli are investigated by small-angle neutron scattering (SANS) and mechanical measurements. These gels have unique structures, such as sliding cross-links (slide-ring gels), plane cross-links by clay platelets (nanocomposite gels; NC gels), and tetrahedral networks (tetra-PEG gels). One of the common features of these gels is that frozen inhomogeneities inherent in polymer gels are negligible. This fact, observed by SANS measurements, indicates that cross-links are introduced very effectively. Hence, the mechanical properties of these gels are expected to be well predicted by the theories of rubber elasticity. In this review, we discuss the relationship between the structure and mechanical properties of tough polymer gels. Furthermore, we address the necessary conditions for high-performance polymer gels in the analogy of rubber.
Keywords: Small-Angle Neutron Scattering / Gels / Mechanical Properties / Nanocomposite Gels / Slide Ring Gels / Double Network Gels / Tetra-PEG Gels Rubber Elasticity
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Structures and Dynamics of Supramolecular Polymeric Systems Toshiyuki SHIKATA
<Abstract> Benzene or cyclohexane type gelator compounds bearing a three-alkyl chain via amide groups at their 1, 3, 5 positions form helically or straightly growing supramolecular polymers with large electric dipoles due to 3-fold hydrogen bond formation in low viscous apolar organic solvents. Consequently, gel-like highly viscoelastic materials are obtained. The obtained gel-like materials show relaxing viscoelastic behavior well described with a single Maxwell element and Debye-type dielectric relaxation.
Keywords: Gelator / Supramolecular Polymer / Electric Dipole / Dielectric Relaxation / Viscoelasticity / Rheology / Relaxation Time
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COVER STORY:Topics and Products
Nonlinear Mechanical Phenomena in Gels Yoshimi TANAKA
<Abstract> Mechanical nonlinearity of gels is involved in various strongly irreversible phenomena, such as fracture, friction and impact. In the first part of this report, we focus on yielding deformation and high toughness of double-network gels. In the latter part, we reconsider a well-known mechanical property of gels, stretch-induced swelling.
Keywords: DN Gel / Yielding / Toughness / Swelling
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Aqua Materials : A Possible Direction of Material Design toward the Realization of a Low-Carbon Society Takuzo AIDA
<Abstract> Water and clay (2-5%) quickly form a transparent hydrogel upon mixing with a minute amount of a dendritic molecular glue carrying multiple guanidinium ion pendants (< 0.15%). This material can be molded into shape-persistent freestanding objects owing to its high mechanical strength, and instantaneously self-heals when destroyed.
Keywords: Hydrogel / Clay / Dendrimer / Molecular Glue / Healing / Supramolecular Chemistry
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Polymer Network Fabricated from Tetra-Arm Polymer Unit Takamasa SAKAI
<Abstract> Generally, polymer gels have inhomogeneous network structures, because transient structures are frozen in the crosslinking process. Recently, we fabricated the homogeneous network structure, Tetra-PEG gel, using the tetra-arm polymers as network modules. In this paper, we discuss the gelation process and mechanical properties of Tetra-PEG gel.
Keywords: Tetra-Arm Polymer / Ideal Polymer Network
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Magnetic Gel That Demonstrates Drastic Changes in Dynamic Modulus Tetsu MITSUMATA
<Abstract> A new class of magnetorheological gel that demonstrates drastic and reversible changes in dynamic modulus without using strong magnetic fields was obtained. The magnetic gel consists of carrageenan of polysaccharides and carbonyl iron particles. The magnetic gel exhibited a reversible increase by factors of 500 of the storage modulus and 1200 of the loss modulus upon a magnetic field of 500 mT.
Keywords: Magnetic Gel / Magnetorheology / Stimuli-Responsive Gel
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Photo-Controllable Microfluidic System Composed of a Photo-Responsive Hydrogel Sheet Kimio SUMARU
<Abstract> By using a photo-responsive hydrogel sheet, we constructed a photo-controllable microfluidic system, and demonstrated that microchannels along an arbitrary pathway can be formed instantly just by micro-patterned light irradiation using a micro-projection system in an gon-demandh manner. Also we constructed 10 photo-controllable microvalves integrated within a 1 cm-square-area by combining a similar system with a PDMS microchannel chip, and demonstrated that all the microvalves can be controlled independently by local light irradiation.
Keywords: Photo-Responsive Hydrogel / Microfluidics / Spiropyran / Micro-Patterned Light Irradiation / Microvalves
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Gel Electrolytes for Electric Double-Layer Capacitor Masashi ISHIKAWA
<Abstract> Gel electrolytes for an electric double-layer capacitor (EDLC) require high ionic carrier density and mobility. The present article overviews conventional and novel materials for EDLC gel electrolytes, and illustrates a practical EDLC module with a gel electrolyte.
Keywords: Capacitor / Gel Electrolyte / EDLC / Electric Double Layer
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Drug Delivery through Soft Contact Lenses Haruyuki HIRATANI
<Abstract> The simplicity of use and low cost of manufacturing make soft contact lenses an attractive platform for ocular drug delivery systems. The possibility of both vision correction and acting as a drug delivery system could remarkably enhance the benefits of soft contact lenses.
Keywords: Hydrogel / Drug Delivery / Molecular Imprint
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Front-Line Polymer Science
Physical Properties of Polymers Studied by Utilizing Rheological Measurements : From Introduction to Application in Industry Yoshiaki TAKAHASHI
<Abstract> In this article, some topics of recent advances in physical properties and the relation with structure for polymers are briefly reviewed. Topics included are, viscoelastic properties of cyclic polymer and loop/bridge/dangling end problems in polymer networks as fundamental ones. Two topics about improvement of polymer processing by utilizing rheological measurements are introduced as industrial application. A few other topics in nonlinear rheological properties which are under the progress are mentioned.
Keywords: Entanglements / Ring Polymer / Loop / Bridge / Dangling End / Polymer Processing / Strain Hardening / Shear Banding
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