| 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 “close encounters of new kinds”, not only in the field of research but also in many other fields. Maintaining your interest in those “close encounters” 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 “on-demand” 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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