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Volume 72, Issue 12
Displaying 1-11 of 11 articles from this issue
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Comprehensive Papers
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Yuta KODA, Takaya TERASHIMA, Mitsuo SAWAMOTO2015 Volume 72 Issue 12 Pages 691-706
Published: December 25, 2015
Released on J-STAGE: December 25, 2015
Advance online publication: November 09, 2015JOURNAL FREE ACCESSThis comprehensive article summarizes our recent efforts to create fluorous nanospaces with microgel-core star polymers and amphiphilic random copolymers via living radical polymerization for molecular encapsulation and bioapplication. Fluorous microgel star polymers were obtained in high yield from ruthenium-catalyzed crosslinking reactions of hydrophobic poly(methyl methacrylate) or hydrophilic poly(ethylene glycol) (PEG) arms with perfluorinated methacrylates; the star polymers serve as homogeneously-soluble fluorous nanocapsules to selectively encapsulate and release perfluorinated compounds in organic solvents or water. Fluorous star polymers with PEG arms and the star polymer gels were particularly effective for the removal of potentially toxic perfluorinated surfactants in water. In contrast, amphiphilic/fluorous random copolymers gave dynamic fluorous nanospaces via single-chain folding and/or multi-chain aggregation in water. The fluorous core aggregates were non-cytotoxic and afforded protein conjugation. Thus, fluorous nanocapsules consisting of microgel star polymers and amphiphilic random copolymers would open new vistas in molecular encapsulation/separation technologies and biochemical and biomedical applications.View full abstractDownload PDF (1877K) -
Takanori TADA, Noboru KITAMURA, Tatsuya SHOJI, Yasuyuki TSUBOI2015 Volume 72 Issue 12 Pages 707-720
Published: December 25, 2015
Released on J-STAGE: December 25, 2015
Advance online publication: November 24, 2015JOURNAL FREE ACCESSAqueous solutions of thermo-responsive polymers represented by poly(N-isopropylacrylamide) (PNIPAM) exhibit a coil-to-globule phase transition followed by phase separation upon temperature increase. These polymers are promising smart materials that can form the basis for drug delivery systems. In order to apply these polymers as smart materials, it is necessary to acquire a precise knowledge on the dynamic behavior of phase separation. Recently, we developed a technique that combined a laser-induced temperature-jump with transient photometry to reveal the phase sepation dynamics in aqueous PNIPAM solutions. By using this particular technique, we demonstrated that the phase separation accerelated with increasing the polymer concentration. Furthermore, we found that the molecular weight of polymers and the stereoregularity of polymers influence the phase separation dynamics. Our observations will offer a new avenue for the design and development of thermo-responsive-polymer-based smart materials whose responsiveness can be controlled via the stereoregularity of the polymer.View full abstractDownload PDF (1447K)
Original Papers
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Shinji ASAI, Hiroshi NONAKA, Masamitsu FUNAOKA2015 Volume 72 Issue 12 Pages 721-725
Published: December 25, 2015
Released on J-STAGE: December 25, 2015
Advance online publication: November 02, 2015JOURNAL FREE ACCESSIn the past only on the distribution pattern of lignin in the whole tree trunk had been published, but no studies on the lignin polymer structure had been reported. In this study, we took wood meal samples from various parts of the trunk of a 50 year old cedar. Using our original method, native lignin in each wood meal was converted to lignophenol, the lignin derivative highly conserving the primary lignin chain constructed by radical coupling of lignin monomers. The structures of lignophenol are compared in the horizontal and fiber directions of the trunk. We found that the structure of native lignin seamlessly change in the trunk. The lignin in the central-lower part of the trunk is more condensed and the primary lignin chains are shorter. The primary lignin chains become longer and more linear toward the outer and upper part of the trunk.View full abstractDownload PDF (841K) -
Keiya OBUCHI, Yoko SATO, Yoshiyuki OSAKI, Michinori KARIKOMI, Takao KI ...2015 Volume 72 Issue 12 Pages 726-730
Published: December 25, 2015
Released on J-STAGE: December 25, 2015
Advance online publication: October 30, 2015JOURNAL FREE ACCESSFor the purpose of chemical recycling of waste windshield polyvinyl butyral (PVB) interlayers, novel PVB organogels were prepared by the gelation of PVB containing PVA units of ca. 20 mol% with pyromellitic dianhydride (PMDA) as crosslinker and phthalic (PAH) or trimellitic anhydrides (TAH) as a chemical modifier. The resulting PVB organogels had a high swelling degree in organic solvents such as N,N-dimethylformamide and methanol in the solubility parameter 12 to 15 region. The order of swelling degree was as follows: PVB organogel prepared with PMDA+TAH > that with PMDA+PAH > that with only PMDA. The swelling degree drastically increased with an increase of the amount of carboxy groups introduced in the organogels, because conversion of carboxy groups into carboxylate ions was promoted by triethylamine used as base-catalyst.View full abstractDownload PDF (783K) -
Yu KOBAYASHI, Erika TAGUCHI, Michinori KARIKOMI, Takao KIMURA2015 Volume 72 Issue 12 Pages 731-736
Published: December 25, 2015
Released on J-STAGE: December 25, 2015
Advance online publication: September 25, 2015JOURNAL FREE ACCESSFor use as a water reserving material, interpenetrating polymer network (IPN) hydrogels were prepared by combination of chemical crosslinking of polyitaconic acid with amidic type crosslinker and physical crosslinking of polyvinyl alcohol (PVA) based on hydrogen bonding. With an alteration in the degree of polymerization (n) of PVA (1000, 2000 or 4000) and of the added amount, the resulting IPN hydrogels were evaluated on water retentivity, compressive strength, and re-swelling. When PVA of n = 2000 was used, it was possible to produce higher swellable IPN hydrogels. With an increase in the amount of PVA, the swelling degree of IPN hydrogels in deionized water decreased, whereas the compressive strength increased according to the maximum load point. By repeating the swelling-drying process, it was proved that high re-swelling ability of IPN hydrogels is kept as both, n of PVA and the added amount increase. The water retentivity of soils increased with the addition of more IPN hydrogel. Moreover, preferable growth of white radish sprouts was observed in cultivation on the IPN hydrogels containing calcium ions as counter cation of the carboxylate anion.View full abstractDownload PDF (928K) -
Takuro ISHIZAKI, Shuntaro UENUMA, Seiichi FURUMI2015 Volume 72 Issue 12 Pages 737-745
Published: December 25, 2015
Released on J-STAGE: December 25, 2015
Advance online publication: October 23, 2015JOURNAL FREE ACCESSNatural polymers such as cellulose are known to form cholesteric liquid crystal (CLC) phases after chemical modification of their side chains. We report on the synthesis of hydroxypropyl cellulose (HPC) ester derivatives and the dependence of their Bragg reflection wavelength on temperature. The reflection wavelengths shifted to longer wavelengths upon heating due to an increase in the CLC helical pitch. When the HPCs were chemically modified by both propionyl and another functional groups such as the cholesteryl moiety, we successfully demonstrated the continuous tuning of the reflection peak throughout the full visible-wavelength range from 400 nm to 800 nm by sweeping the temperature between 30°C and 80°C.View full abstractDownload PDF (888K) -
Toshinori MORISAKU, Yusuke SOHARA, Hiroharu YUI2015 Volume 72 Issue 12 Pages 746-751
Published: December 25, 2015
Released on J-STAGE: December 25, 2015
Advance online publication: September 25, 2015JOURNAL FREE ACCESSWe investigated the thermal denaturation of type I collagen fibrils with vibrational circular dichroism (VCD) spectroscopy. The VCD spectrum of the fibrils showed an amide I band that comprised two right-handed optically active peaks at around 1635 cm−1 and 1660 cm−1. On the other hand, the triple-helical structure of collagen molecules, namely the unit structure of the fibrils, showed right-handed and left-handed amide I bands at around 1620 cm−1 and 1680 cm−1, respectively. Because the bands for the fibrillar structure were different from those for the triple-helical structure, VCD spectra enabled us to discriminate between the fibrillar and triple-helical structure. In addition, from VCD spectral changes accompanying the thermal denaturation of the fibrils, we found a new intermediate structure in the transition from triple-helical to unordered structure that is characterized by a broad right-handed band at around 1650 cm−1.View full abstractDownload PDF (678K) -
Tao WANG, Masamiki SOEDA, Seung-Woo LEE2015 Volume 72 Issue 12 Pages 752-759
Published: December 25, 2015
Released on J-STAGE: December 25, 2015
Advance online publication: November 25, 2015JOURNAL FREE ACCESSIn this study, we demonstrated a novel method for the selective and sensitive detection of polyamines in aqueous solutions using gold nanoparticles (c-AuNPs) protected with citric acid. The polyamine spermine (SPM) has attracted a great deal of attention as a cancer marker that is usually found at high concentrations in the urine of cancer patients. The c-AuNPs with a diameter 20 nm showed a limit of detection of 5 µM to SPM along with a very fast reaction time of less than 10 sec. The color of the solution of c-AuNPs immediately changes from red to blue when mixed with SPM, indicating the acid-base-induced aggregation of c-AuNPs. The absorbance at around 700 nm significantly increases in the presence of SPM. The particle size of c-AuNPs is an important parameter for polyamine assessment. Real urine and SPM-spiked urine samples were analyzed and showed similar spectral changes in the absorption bands, which had been observed with a pure SPM solution in water. It is confirmed that polyamines in urine can be sensitively detected via colorimetric analysis using c-AuNPs.View full abstractDownload PDF (954K) -
Saori SASAKI, Seido YARIMITSU, Teruo MURAKAMI, Atsushi SUZUKI2015 Volume 72 Issue 12 Pages 760-764
Published: December 25, 2015
Released on J-STAGE: December 25, 2015
Advance online publication: December 04, 2015JOURNAL FREE ACCESSThe frictional properties of PVA cast gel prepared under different conditions have been investigated. Optimum drying humidity (60%RH) or low drying temperature conditions caused a decrease in the coefficient of friction in the reciprocating test. As the drying humidity increased, the surface of the gel became flat and smooth. On the other hand, when the drying temperature became lower, lubrication improved by elution of the polymer. In addition, the layered PVA cast gel maintained a lower coefficient of friction throughout the reciprocating test. From the results, it was shown that the excellent frictional properties could be maintained by controlling the preparation conditions.View full abstractDownload PDF (830K) -
Isamu RIKU, Koji MIMURA2015 Volume 72 Issue 12 Pages 765-772
Published: December 25, 2015
Released on J-STAGE: December 25, 2015
Advance online publication: October 19, 2015JOURNAL FREE ACCESSTo take advantage of the toughness mechanism of Double Network Hydrogels (DN gels) and explore the possibility for applications in engineering as a structural member, the establishment of a mechanical model of DN gels is indispensable. Therefore, in this paper, we, at first, propose the development of the equations of a dynamic model, which depends on the number of molecular chain segments of the DN gel and is based on the affine molecular chain network theory. A 8-chain affine model reproduces the affine deformation of DN-gels successfully. Finally, a simulation is performed for the nonuniform DN gel and the microscopic distribution of the number of molecular chain segments and the stress are calculated.View full abstractDownload PDF (806K)
Notes
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Naotaka NISHIMURA, Yoshiaki HIRANO2015 Volume 72 Issue 12 Pages 773-776
Published: December 25, 2015
Released on J-STAGE: December 25, 2015
Advance online publication: November 25, 2015JOURNAL FREE ACCESSPolysaccharides such as alginate or chitosan have gained increasing attention for applications as soft biomaterials. In particular, alginate-Ca2+ hydrogel has been applied to food chemistry and as a tissue engineering scaffold. In this study, we prepared an alginate nanofiber without Ca2+ ions that utilizes self-assembling β-sheet peptides as the cross-linker for the hydrogel. We designed this cross-linker from a sequence of hydrophilic and hydrophobic amino acids, such as (KLVFF)4, and immobilized the self-assembled β-sheet peptides to the -COOH group of the alginate to form cross-links. We then investigated the molecular conformation of the self-assembled β-sheet peptides in solution by circular dichroism and infrared spectroscopy.View full abstractDownload PDF (420K)
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