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Volume 65, Issue 6
Displaying 1-8 of 8 articles from this issue
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Comprehensive Papers
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Junji WATANABE, Mitsuru AKASHI2008 Volume 65 Issue 6 Pages 387-398
Published: 2008
Released on J-STAGE: June 25, 2008
JOURNAL FREE ACCESSNano-hybridization facilitates the performance of materials; in particular for applications in the biomedical field. In this paper, we focus on organic-inorganic nano-hybrid materials. As organic materials, polyester porous membranes and bio-based hydrogels were used. The nano-hybrid approach was based on coating techniques, which were classified as ‘two dimensional’, ‘three dimensional’, and ‘space-time interval regulated’ coatings. The preparation involved alternate soaking and electrophoresis. Moreover, the alternate soaking method was integrated with electrophoresis, and the formation of an anisotropic nano-hybrid material was achieved. Finally, inorganic lamination using hydroxyapatite and calcium carbonate was successfully achieved. These findings related to nano-hybrid materials are of great importance for the preparation of high performance biomaterials.
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Masayoshi HIGUCHI2008 Volume 65 Issue 6 Pages 399-404
Published: 2008
Released on J-STAGE: June 25, 2008
JOURNAL FREE ACCESSOrganic-metallic hybrid polymers are synthesized by self-assembly of organic modules with metal ions such as Fe(II) and Co(II). The resulting polymers have a specific color based on the metal-to-ligand charge transfer (MLCT) absorption. The electrochromic properties of the hybrid polymers are shown by electrochemical redox of the metal ions in the polymer. The color of the polymers can be controlled by changing the organic modules or metal species. In addition, multi-color electrochromic change of the polymers is achieved by introducing two kinds of metal species into the polymer chain. Electrochromic devices using the hybrid polymers will be applied in manufacturing electronic paper products.
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Yukio NAGASAKI2008 Volume 65 Issue 6 Pages 405-415
Published: 2008
Released on J-STAGE: June 25, 2008
JOURNAL FREE ACCESSAn advanced hybrid drug carrier has been developed using porous nanocrystals of a swellable clay mineral conjugated with a block copolymer containing poly(ethylene glycol) and polyamine segments. Synthetic hectorite (Laponite) or silica nanoparticles modified with α-acetal-poly(ethylene glycol)-block-poly[2-(N,N-dimethylamino)ethyl methacrylate] (acetal-PEG-b-PAMA) produced a homogeneous dispersion of an organic-inorganic hybrid in aqueous solution, which showed flocculation-resistive properties with an elevated ionic strength. The zeta-potential measurement revealed that nonionic PEG brush layers are formed on the surface of the clay nanocrystals since the negative charge of the clay surface was completely shielded by the nonionic PEG segment in the block copolymer. This charge neutralization explains the dispersion stability in solutions of high ionic strength. The average particle size of the PEG-modified hybrid was estimated to be 30—120 nm by dynamic light scattering. Pyrene, used as the model compound of a hydrophobic drug, was incorporated into the nanopores of the clay mineral without any remarkable expansion of the basal spacing. On the basis of these results, hybrids of porous inorganic nanoparticles coupled with acetal-PEG-b-PAMA are promising as new drug carrier systems.
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Original Papers
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Takahiro GUNJI, Yosuke SUETAKA, Yoshimoto ABE, Shinji INAGAKI, Satoru ...2008 Volume 65 Issue 6 Pages 416-420
Published: 2008
Released on J-STAGE: June 25, 2008
JOURNAL FREE ACCESSPolysiloxanes were synthesized by the hydrolytic polycondensation reaction of benzene-bridged alkoxysiloxanes such as 1,4-bistriethoxysilylbenzene or 1,4-bisdiethoxy(methyl)silylbenzene in a nitrogen flow. Highly flexible free-standing films were prepared by heating ethanol solutions of these polysiloxanes. The hardness of these free-standing films increased with increasing molecular weight and heating period due to the increase in the condensation degree of siloxane.
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Mineo HASHIZUME, Yoshihiro SASAKI, Takashi TERASHIMA, Takayoshi KOMATS ...2008 Volume 65 Issue 6 Pages 421-426
Published: 2008
Released on J-STAGE: June 25, 2008
JOURNAL FREE ACCESSOrganized assemblies of cerasomes, organic-inorganic vesicular nanohybrid shaving an atomic layer of siloxane network on their surface, were created using DNA molecule as the template through electrostatic interactions. Various physical measurements such as dynamic light scattering, differential scanning calorimetry, fluorescence polarization, and transmission electron microscopy revealed that small unilamellar vesicles (SUVs) of cationic cerasomes assembled on calf thymus DNA while maintaining their vesicular structure. On the other hand, SUVs made from cationic reference lipids were unable to maintain their vesicular structures and fused to form multilamellar vesicles on the DNA. These results show that cerasomes form organized assemblies because of their remarkably high morphological stability.
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Masataka KUBO, Yohei WAKAMATSU, Takahiro UNO, Takahito ITOH, Masashi S ...2008 Volume 65 Issue 6 Pages 427-432
Published: 2008
Released on J-STAGE: June 25, 2008
JOURNAL FREE ACCESSOrange, green, and blue fluorescent poly(arylene vinylene)s were prepared by the Wittig reaction. A purple fluorescent poly(fluorene phenylene) carrying hydroxy functionality was prepared by the Suzuki coupling reaction. Polycondensation of tetraethoxysilanes was carried out in the presence of these polymers to give spherical silica hybrids as new photoluminescent materials. White light emission was observed utilizing these hybrids as phosphors for ultra-violet light emitting diodes.
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Junji SHIRAI, Makoto KATO, Isamu INAI, Hiroyuki WAKABAYASHI, Hirotaka ...2008 Volume 65 Issue 6 Pages 433-439
Published: 2008
Released on J-STAGE: June 25, 2008
JOURNAL FREE ACCESSAcrylonitrile-Butadiene-Styrene Copolymer(ABS)/Clay Nanocomposites have been prepared by the melt intercalation method with a twin screw extruder. In the nanocomposite, the silicate layers of montmorillonite were not exfoliated to monolayers, but were dispersed to 5 to 10 stacked layers. These stacked silicate layers of montmorillonite were around butadiene rubber domains of the high impact polystyrene in ABS. This unique dispersion state is the result from the intercalation of polystyrene into silicate layers. When 5 wt% clay was added, tensile modulus was 1.2 times greater than that of ABS.
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Kimihiro MATSUKAWA, Yukihito MATSUURA, Kouji KATAYAMA, Noboru NISHIOKA ...2008 Volume 65 Issue 6 Pages 440-444
Published: 2008
Released on J-STAGE: June 25, 2008
JOURNAL FREE ACCESSPhotofunctional polymethylphenylsilane (PMPS) and toluene dispersed silica nano-particles (13 nm average diameter) were used for the preparation of organic-inorganic hybrid thin films. The surface of silica nano-particles were modified with phenyl and methyl groups. The thin films were prepared by spin-coating the toluene solution of PMPS and silica nano-particles on quartz and silicon substrates, respectively. The UV spectra of polysilane/phenyl modified silica nano-particle hybrid thin films indicated a red-shift of absorption peak related to the Si-Si bond in PMPS. This interesting phenomenon was caused by the longer σ-conjugation due to the stretched Si-Si bond, which was resulted from the π-π interaction of phenyl groups between PMPS and surface of silica nano-particles. Furthermore, after UV irradiation and heat treatment of the hybrid thin films containing small amount of PMPS, the cross-linked nano porous silica thin films with a low refractive index were obtained.
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