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Volume 65, Issue 7
Displaying 1-8 of 8 articles from this issue
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Review Articles
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Kohzo ITO2008 Volume 65 Issue 7 Pages 445-457
Published: 2008
Released on J-STAGE: July 25, 2008
JOURNAL FREE ACCESSSince the discovery of cross-linking in natural rubber with sulfur in 1839 by Goodyear, the cross-linking of polymeric materials has become one of the most important topics in polymer science and technology. We have recently developed a novel type of gel called the slide-ring gel or topological gel that is different from physical and chemical gels by using a supramolecular architecture with topological characteristics. In this gel, polymer chains with bulky end groups exhibit neither covalent cross-links as in chemical gels nor attractive interactions as in physical gels but are topologically interlocked by figure-of-eight cross-links. Hence, these cross-links can pass along the polymer chains freely to equalize the tension of the threading polymer chains similarly to pulleys; this is called the pulley effect. The slide-ring material is a new cross-linking concept for the polymer network as well as a real example of a slip-link model or sliding gel, which was previously considered only theoretically. In this report, we review recent research on progress in the cross-linking of polymeric materials together with the synthesis, structure, and mechanical properties of the slide-ring gels. This concept of the slide-ring material can be applied to not only gels but also to a wide variety of polymeric materials without solvents.
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Original Papers
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Yuji NISHIKAWA, Kazutaka FUKUI, Yasuhiro MATSUDA, Shigeru TASAKA2008 Volume 65 Issue 7 Pages 458-464
Published: 2008
Released on J-STAGE: July 25, 2008
JOURNAL FREE ACCESSDifferential scanning calorimetry (DSC), dielectric relaxation measurement, friction measurement, and infrared spectroscopy were used to characterize addition-cured silicone pressure-sensitive adhesive (ASPSA). A stepwise decrease was observed at 30°C for the heat capacity of crosslinked ASPSA in contact with metal or metal oxide, while there was no step decrease for non-crosslinked ASPSA in contact with metal or metal oxide. The mechanism of adhesion of ASPSA is discussed based on the interaction between silicone resin in ASPSA and metal interfaces.
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Junichi KAMEDA, Yasuhiro SHIBATA, Hiroaki KOUZAI2008 Volume 65 Issue 7 Pages 465-470
Published: 2008
Released on J-STAGE: July 25, 2008
JOURNAL FREE ACCESSWe confirmed the photodegradation of vulcanized rubbers in solution by a sensitizer. Our results show that the molecular weights of the polymers were markedly lowered by the degradation by UV-irradiation when a sensitizer was added. Especially, strong effects on the degradation of diene polymers were observed by using hydrocarbon sensitizers such as anthraquinone. In addition, the degradation products exhibited increased solubility, and were dissolved in various organic solvents. FT IR and 1H NMR spectra of the irradiated polymers indicated that the -OH and =CO groups were generated, while olefinic groups decreased in number. Therefore, the degradation of the vulcanized rubber is considered to proceed through the scission of the polymer main chain.
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Midori KAMEI, Kazuhide KURATANI, Maki IWANAGA, Namiko INABA, Hiroaki K ...2008 Volume 65 Issue 7 Pages 471-476
Published: 2008
Released on J-STAGE: July 25, 2008
JOURNAL FREE ACCESSNovel linear polyurethanes were synthesized by the reaction of methyl(S)-2,6-diisocyanatohexanoate (LDI) with bis(2-hydroxyethyl) terephthalate (BHET) and poly(ethylene glycol) (PEG). The polymers were obtained in relatively high yields (95~98%). Their number-average molecular weights determined by GPC were in the range from 2.1×104 to 2.4×104 and the polymers showed a glass-transition temperature at about −13°C by dynamic mechanical analysis. The polymers were rubber-like, elastic materials with high tensile strength of ca. 83 MPa. Enzymatic degradation of the polymers esulted in a weight loss of up to 98%. Moreover, numerous holes and hollow structures were observed on the surface of the degraded films by scanning electron microscopy.
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Toru ONISHI, Hyoe HATAKEYAMA, Tatsuko HATAKEYAMA2008 Volume 65 Issue 7 Pages 477-482
Published: 2008
Released on J-STAGE: July 25, 2008
JOURNAL FREE ACCESSCarboxymethylcellulose (CMC)-based polyurethane (PU) hydrogels were prepared from the solutions of CMC and hexamethylene diisocyanate (HDI). Water content [Wc=(mass of water)/(mass of dry sample)] of the obtained PU hydrogels was less than 3.0 g g−1 and NCO/OH ratio was varied from 0.2 to 0.6 mol mol−1. Phase transition behaviour of CMC-water systems and CMC-PU hydrogels was investigated in the temperature range from −150 to 80°C by differential scanning calorimetry (DSC). From DSC heating curves, glass transition temperature (Tg), melting peak at low temperature side (Tml), and melting peak at high temperature side (Tmh) were observed. The Tg minimum value increased with increasing NCO/OH ratio indicating that the molecular motion is restricted by cross-linking. From the enthalpy of melting, it was confirmed that there exist three kinds of water, non-freezing water, freezing bound water and freezing water respectively.
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Mariko AGO, Kazuishi SATO, Takashi ENDO, Kunihiko OKAJIMA2008 Volume 65 Issue 7 Pages 483-492
Published: 2008
Released on J-STAGE: July 25, 2008
JOURNAL FREE ACCESSCrystalline cellulose was ball-milled in the presence of a hydrophilic or low polarity solvent, and the changes in the solid structure caused by interaction with the solvent were analyzed by NMR relaxation time and thermally stimulated depolarization current (TSDC) method. The cellulose particles were prepared by ball-milling with obviously different morphology and crystallinity depending on the nature of solvents. The molecular mobility of cellulose chain was enhanced by the interaction of hydrophilic solvents compared with the interactions of low polarity solvents. The TSDC analyses of the cellulose with different morphology and crystallinity confirm the existence of α, β and γ relaxations. The intensities of α and β relaxations increased with decreasing in crystallinity of the cellulose, accompanied with a shift of the peak temperature to lower values. The γ relaxation was proved to be independent from other two relaxations. The presence of water in the cellulose gave higher intensity of α and β relaxations, while the presence of toluene mainly affected the intensity and peak temperature of the β relaxation. The study on local relaxation modes of solid cellulose revealed the specific interaction of cellulose chains and solvents molecule, depending on the solvent charateristics.
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Notes
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Masahiko OSHIGE, Mieko KATSUMATA, Daisuke IWASAKI, Keijyu YAMAZAKI, Sh ...2008 Volume 65 Issue 7 Pages 493-495
Published: 2008
Released on J-STAGE: July 25, 2008
JOURNAL FREE ACCESSAs nanotechnology has been developed, various nanoparticles and elemental device have been studied intensively. These studies suggest that new materials can be created by regular arranging of nanoparticles. However, a method for the arranging has not been developed sufficiently. We tried to arrange by using DNA molecules and the DNA sequences recognition peptide-conjugated nanoparticles. To achieve this goal, we investigated the following topics: 1) sample preparation of DNA sequence recognition peptide-conjugated nanoparticles; 2) complex formation of DNA and DNA sequence recognition peptide conjugated nanoparticles; 3) observation and evaluation of them by Atomic Force Microscope (AFM) techniques. We succeeded in the conjugation of the nanoparticle and the DNA sequence recognition peptide, the formation of the DNA and the peptide-conjugated nanoparticle complexes, and thearrangement of the nanoparticles in a target place on DNA.
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Manabu YAMAZAKI, Tomohiro SUZUKI, Toshiki HAGIWARA, Takashi SAWAGUCHI, ...2008 Volume 65 Issue 7 Pages 496-498
Published: 2008
Released on J-STAGE: July 25, 2008
JOURNAL FREE ACCESSNovel poly[2]catenane having rigid triazole rings between [2]catenanes was synthesized by 1,3-dipolar cycloaddition of diazido[2]catenane and 4,4′-diethynylbiphenyl. The reaction proceeds effectively in mild conditions and gave the polymer in high yield. The number-average molecular weight (Mn) of the polymer is 1.5×104 and the Mn/Mn is 2.0. A cyclic dimer constructed from two [2]catenanes and two biphenyls was formed along with the polymer, but the cyclodimerization was inhibited by conducting the reaction at low temperature without lowering the yield or the molecular weight of the polymer.
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