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Volume 59, Issue 12
Displaying 1-13 of 13 articles from this issue
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Shigeki HABAUE, Masatake MORITA, Yoshio OICAMOTO2002 Volume 59 Issue 12 Pages 717-724
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSNovel types of vinyl polymers with a macrocyclic side chain were synthesized by the anionic polymerization of α- (alkoxymethyl) acrylate derivatives having 13-17 membered ring structure. The counter-cation in the polymerization system strongly affected the polymer yield and stereoregularity. The polymers bearing a crown ether side chain showed selective alkali-ion extraction abilities, which were significantly affected by the tacticity, as well as the ring structure, and very different from the other typical polymers having a crown ether side chain. The cobalt ion transport abilities were also demonstrated using vesicles prepared with dihexadecyl phosphate, suggesting that the polymers may have a porous or nanotube structure suitable as synthetic ion channels.View full abstractDownload PDF (1437K) -
Shinjiro MACHTDA, Kazuyuki HORIE2002 Volume 59 Issue 12 Pages 725-733
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSWe performed photochemical hole burning spectroscopy with several kinds of nanostructured polymer systems: a DNA-lipid complex, unimacromolecular micelles, dendrimer porphyrins, and mutated proteins. Nanoscopic environments around the dye, including structural relaxation at low temperatures and electron-phonon interactions are evaluated for these systems. DNA-lipid complex film showed marked hole broadening but no hole filling at 40 K. We attributed this result to the intercalation of porphyrin molecules into the double helix of DNA. Molecular weight dependence of phonon frequency of the unimacromolecular micelle systems showed that the electron-phonon interaction is effective within 2.3 nm around the dye. Dendrimer porphyrin neat films showed sharp holes at 20 K. Hole areas of dendrimer porphyrins of higher generation showed better temperature stability, reflecting the the surface mobility. A mutated cytochrome b562, which has aspartic acid instead of asparagine in the wild type, showed stepwise hole broadening at 35 K. This was the first observation of a mutual relationship between the location of the site where the structural relaxation occurs and the increase in holewidth.View full abstractDownload PDF (2122K) -
Tooru OOYA, Masaru EGUCHI, Nobuhiko YUI2002 Volume 59 Issue 12 Pages 734-741
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSVarious kinds of ligands were introduced to hydroxyl groups in α-cyclodextrin and the derivatives were threaded onto a poly (ethyleneglycol) chain capped with biodegradable end-groups (biodegradable polyrotaxane). Multivalent interactions between ligand-polyrotaxane conjugates and binding proteins were kinetically proved by surface plasmon resonance analysis. We have clarified the effects of rod-like structure of the polyrotaxanes on ligands-receptor interactions such as biotin-streptavidin, dipeptides-peptide transporter, and glucose-Concanavalin A interactions. Such supramolecular effects were observed in the complex formations by calcium chelation. Supramolecular dissociation via the terminal hydrolysis was advantageous for switching from multivalent to monovalent interactions, which are likely to be applicable to biomedical applications.View full abstractDownload PDF (1696K) -
Keigo AOI, Muneo KATSUBE, Kaname TSUTSUMIUCHI, Masahiko OKADA2002 Volume 59 Issue 12 Pages 742-752
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSAs an architectural strategy toward nano-scale unimolecular building blocks, star-shaped ABn-type block copolymers were synthesized via living ring-opening polymerizations of α-amino acid N-carboxyanhydride monomers initiated with dendrimers having terminal amino groups. Poly (trimethylenei mine) dendrimer-block-polysarcosine [poly (propyleneimine) dendrimer-block-poly (N-methylglycine) (1) ], poly (amido amine) dendrimer-block-polysa rcosine (2), and poly (amidoamine) dendrimer- block-poly [O- (2-acetamido-2-deoxy-β-D-glucopy-ranosyl) -L-serine] (6b) were synthesized by polymerizations of the orresponding NCA monomer with the dendrimer. Molecular size of 1was determined by small angle neutron scattering experiment. It was revealed that the star dendrimer is somewhat shrunk in D2O. In order to utilize the B block segment as an anchor segment, miscibility between poly (vinyl alcohol) (PVA) and 2 was investigated using FT-IR, differential scanning calorimetric, and dynamic mechanical analyses. Although the hydroxyl-terminated poly (amido amine) dendrimer did not show miscibility with PVA, 2 was miscible with PVA. Molecular recognition ability of 6b was examined by erythrocyte agglutination assays using wheat germ agglutinin (WGA) lectin. The oligoglycopeptide-type star dendrimer having N-acetyl-D-glucosamine showed high cell recognition ability.View full abstractDownload PDF (2344K) -
Preparation and Electro-Optic Properties of Liquid-Crystal Displays Doped with Palladium NanoparticlesYukihide SHIRAISHI, Shigenobu SANO, Atsushi BABA, Shunsuke KOBAYASHI, ...2002 Volume 59 Issue 12 Pages 753-759
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSRecently an investigation was reported for improvement of a contrast ratio of liquid-crystalline matrices by addition of fullerene having a nanoscopic structure. However, this system has a disadvantage of poor miscibility of fullerene molecules in the liquid-crystalline medium. Metal nanoparticles stabilized by organic molecules are now creating a new class of materials different from either conventional bulk materials or atoms. This study aims to synthesize liquid-crystalline molecule-protected metal nanoparticles having high solubility into liquidcrystalline matrices and to develop novel display materials. 4-Cyano-4′-pentylbiphenyl (5 CB) -protected palladium (5 CB-Pd) nanoparticles with an average diameter of 1.9 nm were prepared by UV irradiation of a tetrahydrofuran solution of palladium (II) acetate in the presence of 5 CB. A guest-host liquid-crystalline device was fabricated by doping liquid-crystalline host matrices with 5 CB-Pd nanoparticles and a dichroic dye. 5 CB-Pd nanoparticles have higher solubility than fullerene into the liquid-crystalline medium. An electro-optic property in the presence of 5 CB-Pd nanoparticles is much better than that in the absence.View full abstractDownload PDF (1933K) -
Kazunobu YAMADA, Kazue UEDA, Suprakas Sinha RAY, Masami OKAMOTO2002 Volume 59 Issue 12 Pages 760-766
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSNew biodegradable polylactide (PLA) /layered silicate nanocomposites were prepared successfully by simple melt extrusion of PLA and organically modified layered silicate (OMLS). Natural montmorillonite or synthetic fluorine mica modified with several kinds of ammonium cations were examined as OMLS for the intercalated-type nanocomposites preparation. The internal structure of the nanocomposites in the nanometer range has been established by using wide-angle X-ray diffraction and transmission electron microscope analyses. All the nanocomposites exhibited superior improvements of practical material properties, such as storage modulus, flexural modulus, flexural strength, heat distortion temperature, and gas barrier property as compared with the corresponding values of PLA without OMLS. The biodegradability of neat PLA and representative nanocomposites was also studied under compost environment. The rate of biodegradation of PLA matrix significantly increased after nanocomposite preparation.View full abstractDownload PDF (1828K) -
Kanato ADACHI, Atsushi SHISHIDO, Osamu TSUTSUMI, Tomiki IKEDA2002 Volume 59 Issue 12 Pages 767-771
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSPhotochemical phase transition behavior of thin films of the polymer azobenzene liquid crystal (LC) has been investigated with a picosecond laser pulse (355nm, 20ps FWHM). Time-resolved measurements revealed that the photochemical nematic (N) to isotropic (I) phase transition took place in 200ns. This is due to the formation of a large amount of cis-azobenzenes by the high-intensity laser pulse with a short pulse width, followed by disorganization of the phase structure of the N phase by the large amount of the cis-azobenzene molecules. The photoresponse of this polymer azobenzene LC was independent of laser power and temperature. Furthermore, this response was fastest among those reported previously for polymer LCs. It is expected that the polymer azobenzene LCs can be applied in various photonic devices.View full abstractDownload PDF (933K) -
Keita KUROIWA, Takayuki HARADA, Yasuhiro HATANAKA, Kei YASUI, Nobuo KI ...2002 Volume 59 Issue 12 Pages 772-777
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSA new family of supramolecular nano-assemblies is obtained from p, p'-bis- (ω-dipyridyl decylamido) -azobenzene bromide (1) and perfluorinated dicarboxylic acid (HOOC- (CF2) n-COOH: n=5; 2, n=6; 3, n=7; 4, n=8; 5). Their aggregation characteristics are studied by UV-Vis spectroscopy, dynamic light scattering (DLS), FT-IR spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM). The FT-IR spectra of 1-4 in the solid state exhibit υC=O, υOH, and the Fermi resonance peaks at 1685, 2500, and 1900cm-1, respectively. The observed spectral change indicates that 1-4 is complexed by hydrogen bonds formed between the pyridyl and carboxyl groups. When 1-2 and 1-4 are dispersed in CHCl3/CH3OH (39/1 by volume), globular aggregates with the average diameter of 700-1000nm (1-2) and 300-800nm (1-4) are observed by TEM. Consistently, spherical aggregates (diameter: ca. 800 nm (1-2), ca. 400 nm (1-4)) are observed in solution by DLS. Such aggregate structures are not, however, observed for 1-3, 1-5 complexes. Interestingly, nano-ring structures are obtained by dropping CHCl3/CH3OH (39/1 by volume) solution of 1-4 on HOPG. The present supramolecular system provides a novel means to construct molecular patterns which are self-assembled from bifunctional hydrocarbon and perfluorinated subunits.View full abstractDownload PDF (1926K) -
Toshikazu TAKATA, Masanori GOTO, Yoshio FURUSHO, Takashi KATO2002 Volume 59 Issue 12 Pages 778-786
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSBinaphthol derivatives having long alkyl chains on 6- and 6′ -positions (1) were synthesized from (R) -binaphthol. Polycondensation of 1 with bis (4-nitrophenyl) carbonate yielded the corresponding polycarbonate (2, Mn ca. 5000). 2 was also synthesized via a cyclic carbonate (8) derived from 1. The structure simulation of 2 using MM 2 parameters suggested that it adopts a columnar shape of nanometer size. In the CD spectra, 2 showed the opposite Cotton effects to those of the unit model (9), indicating that 2 adopts a stable helical conformation in solution. The intensity of the Cotton effects of 2 decreased with an increase in temperature, suggesting that the helical structure is disordered at high temperatures. Thermal analysis of 2 was also examined by DSC.View full abstractDownload PDF (1981K) -
Masakatsu UKON, Tsuyoshi WATANABE, Takushi SUGINO, Hirosato MONOBE, Yo ...2002 Volume 59 Issue 12 Pages 787-791
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSA triphenylene derivative possessing an acryl group at the peripheral six long chains was synthesized, and the order parameter change during the progress of photopolymerization was investigated by the infrared dichroic method. The C=C and C=0 stretching vibrational bands of the mesogenic molecule were monitored for the evaluation of (local) order parameters. It was found that the order parameter for the triphenylene core decreases up to 70-80% of the initial value with the progress of photopolymerization and the decrease continues till the termination of polymerization (ca. 30% of the residual acryl group). The order parameter shows a rapid decrease at the initial stage of polymerization followed by a gradual declination. On the other hand, the order parameter of the C=0 moieties of the mesogen did not change much in contrast to that of the aromatics, and the value is far smaller. It was shown that the polymerization extent should be controlled at ca. 50% of the acryl residue to obtain the polymer film of a well-aligned nematic order.View full abstractDownload PDF (1058K) -
Takahiro HARADA, Takashi MIYAHARA, Naotoshi NAKASHIMA, Kazue KURIHARA2002 Volume 59 Issue 12 Pages 792-799
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSSurface forces between apposed surfaces modified with thymine (T) or adenine (A) monolayers have been determined by surface forces measurement at various pH's. For a complementary base pair (T-A), a long ranged attraction was always observed, which can be explained by the so-called“long ranged hydrophobic attraction”and electric double layer attraction. On the other hand, the forces between non-complementary base pairs (T-T, A-A) changed from attraction to repulsion depending on pH's, which reflects the acid dissociation of the nucleic acid bases. The acid dissociation constants of T and A on the surfaces were estimated to be ca. 7 and 4, respectively. Adhesive (pull-off) forces have also been measured. The complementary base pair (T-A) showed a larger adhesive force than the non-complementary ones and had a maximum at the neutral pH region, which means that the complementary base pair exhibits the specific molecular recognition ability effectively at the physiological pH region.View full abstractDownload PDF (1839K) -
Atsushi TAKANO, Taro MIYAZAWA, Takatoshi KANO, Hajime OTANI, Shin TSUG ...2002 Volume 59 Issue 12 Pages 800-806
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSTapered block copolymers of styrene and isoprene were prepared by anionic copolymerization of monomer mixtures using sec-BuLi as an initiator in benzene/THF (50/50) at 0°C. Analyses based on both gas chromatography and 1H NMR indicated that monomer composition gradually varied from one chain end to the other. Furthermore, the tapered block copolymers were ozonized so as to decompose 1, 4-microstructure in the polyisoprene sequences. The GPC analysis results of the decomposed products by ozonolysis confirmed that the products had tapered regions in the chains. Two tapered block copolymers with different chain lengths in the tapered region and one regular block copolymer were prepared. Their morphologies were investigated by transmission electron microscopy and small angle X-ray scattering. Microphase-separated structures of three copolymers were revealed to show almost the same alternating lamellar structure.View full abstractDownload PDF (2598K) -
Takahide MIZAWA2002 Volume 59 Issue 12 Pages 807-809
Published: December 25, 2002
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSSynthesis of poly (methyl methacrylate) particles containing inorganic compounds is described. The comonomers were obtained by the reaction of a silane coupling reagent and titanium or zirconium alkoxide as a metal alkoxide. The resulting polymer particles were characterized by IR, SEM and TG-DTA. The particle size was about 70-80nm. The decomposition of the hybrid PMMA/inorganic compound particles started at a higher temperature than that of homo-PMMA particles.View full abstractDownload PDF (1054K)
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