Atsushi Kubono  Kazuki Yoshino  Toshiro Ninomiya  Ryuichi Akiyama  Katsufumi Tanaka 《Liquid crystals》2013,40(8):1089-1095

The visco-elastic properties for binary mixtures of 4-n -hexyloxy-4′-cyanobiphenyl (6OCB) and 4-n-octyloxy-4′-cyanobiphenyl (8OCB) are investigated in detail by a light scattering technique. The mixtures exhibit a reentrant nematic (RN) phase between the smectic A (SmA) and crystal phases in the range 22.0–29.5 wt % of 6OCB. The viscosity and the elastic constant increase with cooling in both the nematic and reentrant nematic phases. It is also found that the mixtures exhibit anomalously large values of viscosity and elastic constant near the phase transition, i.e. a pretransitional phenomenon can be observed. The activation energy for viscosity is smaller in the RN phase than in the ordinary nematic phase appearing at higher temperatures, while the normalized elastic constant (defined as the ratio of the elastic constant to the square of the dielectric anisotropy) is larger. Moreover, the visco-elastic behaviour depends on the specific time during which the sample has been kept in the SmA phase. These results confirm that the SmA phase has a strong influence on the formation of molecular aggregates, which plays an important role in the reentrant phenomenon of these systems.  相似文献   

    

Dr. Nobuhiro Ogihara  Tomomi Yasuda  Yoshihiro Kishida  Dr. Tetsu Ohsuna  Kaito Miyamoto  Dr. Nobuko Ohba 《Angewandte Chemie (International ed. in English)》2014,53(43):11467-11472

As advanced negative electrodes for powerful and useful high‐voltage bipolar batteries, an intercalated metal–organic framework (iMOF), 2,6‐naphthalene dicarboxylate dilithium, is described which has an organic‐inorganic layered structure of π‐stacked naphthalene and tetrahedral LiO₄ units. The material shows a reversible two‐electron‐transfer Li intercalation at a flat potential of 0.8 V with a small polarization. Detailed crystal structure analysis during Li intercalation shows the layered framework to be maintained and its volume change is only 0.33 %. The material possesses two‐dimensional pathways for efficient electron and Li⁺ transport formed by Li‐doped naphthalene packing and tetrahedral LiO₃C network. A cell with a high potential operating LiNi_0.5Mn_1.5O₄ spinel positive and the proposed negative electrodes exhibited favorable cycle performance (96 % capacity retention after 100 cycles), high specific energy (300 Wh kg^?1), and high specific power (5 kW kg^?1). An 8 V bipolar cell was also constructed by connecting only two cells in series.  相似文献   

    

Yoshino A 《Angewandte Chemie (International ed. in English)》2012,51(24):5798-5800

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Hiroaki Shimomoto  Dai Fukami  Tomomi Irita  Ken‐ichi Katsukawa  Takabumi Nagai  Shokyoku Kanaoka  Sadahito Aoshima 《Journal of polymer science. Part A, Polymer chemistry》2012,50(8):1547-1555

Various types of fluorine‐containing star‐shaped poly(vinyl ether)s were successfully synthesized by crosslinking reactions of living polymers based on living cationic polymerization. Star polymers with fluorinated arm chains were prepared by the reaction between a divinyl ether and living poly(vinyl ether)s with fluorine groups (C₄F₉, C₆F₁₃, and C₈F₁₇) at the side chain using cationogen/Et_1.5AlCl_1.5 in a fluorinated solvent (dichloropentafluoropropanes), giving star‐shaped fluorinated polymers in high yields with a relatively narrow molecular weight distribution. The concentration of living polymers for the crosslinking reaction and the molar feed ratio of a bifunctional vinyl ether to living polymers affected the yield and molecular weight of the star polymers. Star polymers with block arms were prepared by a linking reaction of living block copolymers of a fluorinated segment and a nonfluorinated segment. Heteroarm star‐shaped polymers containing two‐ or three‐arm species were synthesized using a mixture of different living polymer species for the reaction with a bifunctional vinyl ether. The obtained polymers underwent temperature‐induced solubility transitions in various organic solvents, and their concentrated solutions underwent sol–gel transitions, based on the solubility transition of a thermoresponsive fluorinated segment. Furthermore, a slight amount of fluorine groups were shown to be effective for physical gelation when those were located at the arm ends of a star polymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

    

Haruhiko Fuwa  Shinya Naito  Tomomi Goto  Makoto Sasaki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2008,120(25):4815-4817

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Takashi Kajiwara  Tomomi Terabayashi  Makoto Yamashita  Kyoko Nozaki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2008,120(35):6708-6712

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Kajiwara T  Terabayashi T  Yamashita M  Nozaki K 《Angewandte Chemie (International ed. in English)》2008,47(35):6606-6610

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Hara K  Akiyama R  Takakusagi S  Uosaki K  Yoshino T  Kagi H  Sawamura M 《Angewandte Chemie (International ed. in English)》2008,47(30):5627-5630

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Ohashi M  Koshiyama T  Ueno T  Yanase M  Fujii H  Watanabe Y 《Angewandte Chemie (International ed. in English)》2003,42(9):1005-1008

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Yoichi Habata  Tomomi Saeki  Sadatoshi Akabori 《Journal of heterocyclic chemistry》2001,38(3):585-590

A series of double armed diaza‐15‐crown‐5 ethers (9a ‐ 16a) and diaza‐18‐crown‐6 ethers (9b ‐ 16b) have been prepared by the Mannich reaction of 2,6‐disubstituted phenols with the corresponding N,N'‐dimethoxymethyldiaza‐crown ethers in benzene. The crystal structures of the diaza‐18‐crown‐6 ethers having iso‐propyl (10b) , tert‐butyl (11b) , and mixed methyl and tert‐butyl groups (12b) at positions 3′ and 5′ of the phenolic side arms were determined using X‐ray diffraction methods. Competitive transport by these ligands for sodium, potassium and cesium cations were measured under basic‐source phase and acidic‐receiving phase conditions.  相似文献