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21.
Kenzo Inoue Hisanori Kaku Hirokazu Hayashi Teiichi Tanigaki 《Journal of polymer science. Part A, Polymer chemistry》1989,27(13):4231-4239
The copolymerization of 4-hydroxy-4′-vinylbiphenyl (HVB) with α-chloromaleic anhydride (CMAn) was investigated in THF, 1,4-dioxane, and acetonitrile. The formation of the 1:1 charge transfer complex between HVB and CMAn was confirmed spectroscopically, and the corresponding equilibrium constant (Keq) was determined as follows: Keq = 0.19, 0.11, and 0.058 mol/L in THF, 1,4-dioxane, and CH3CN, respectively. The copolymer composition is affected by the solvent, i.e., the content of HVB in the copolymer obtained in THF or 1,4-dioxane is lower than 50 mol % whereas the copolymer obtained in CH3CN has excess of HVB units. The maximum rate of copolymerization was observed at a 1:1 initial comonomer mole ratio, irrespective of the solvent polarity. Plots of Rp/[HVB] vs. [HVB] gave a straight line with a slope and an intercept for the copolymerization in THF whereas a straight line in CH3CN has no slope. On the basis of these results and 13C-NMR spectra of the copolymers, the mechanism of the predominant formation of alternating copolymers is discussed. 相似文献
22.
Yohei Uchiyama Shohei Iwasaki Chiaki Ueoka Takashi Fukui Kenzo Okamoto Masayuki Yamaguchi 《Journal of Polymer Science.Polymer Physics》2009,47(4):424-433
Effect of mixing and processing conditions at T‐die extrusion on the structure and mechanical properties is studied for isotactic polypropylene (PP) containing a small amount of β‐form nucleating agent, N,N′‐dicyclohexyl‐2,6‐naphthalenedicarboxamide. It is found that trigonal β crystals are predominantly formed in the extruded samples containing the nucleating agent irrespective of the mixing and processing conditions, leading to the marked mechanical toughness. On the contrary, the molecular orientation is significantly affected by the mixing and processing conditions. In particular, it should be noted that PP molecules in the extruded sheet which was mixed at high temperature (260 °C) and extruded at low temperature (200 °C) orient perpendicular to the applied flow direction. As a result, the sheet shows anomalous mechanical anisotropy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 424–433, 2009 相似文献
23.
24.
Fundamental mechanism of femtosecond-laser-induced periodic surface nanostructure formation has been investigated under the condition using superimposed multiple shots at lower fluence than the single-pulse ablation threshold. With increasing the shot number of low-fluence fs-laser pulses, the periodic nanostructure develops through the bonding structure change of target material, the nanoscale ablation with optical near-fields induced around the high curvatures, and the excitation of surface plasmon polaritons (SPPs) to create the nano-periodicity in the surface structure. It is confirmed that non-thermal interaction at the surface plays the crucial role in the nanostructure formation. Based on the mechanism, we have demonstrated that the periodic nanostructure formation process can be controlled to fabricate a homogeneous nanograting on the target surface, using a two-step ablation process in air. The experimental results obtained represent exactly the nature of a single spatial standing SPP wave mode that generates periodically enhanced near-fields for the nanograting formation. The calculated results for a model target reproduce well the nanograting period and explain the characteristic properties observed in the experiment. 相似文献
25.
26.
Naoko Asakuma Toshimi Fukui Mamoru Aizawa Motoyuki Toki Hiroaki Imai Hiroshi Hirashima 《Journal of Sol-Gel Science and Technology》2000,19(1-3):333-336
Structural changes stimulated by ultraviolet (UV) laser irradiations of sol-gel derived inorganic oxide films were investigated. Dried gel films of TiO2, Nb2O5, Ta2O5, SrTiO3 and Pb(Zr
x
Ti1–x
)O3 (PZT) were found to be crystallized by the laser irradiation. On the other hand, the photo-induced change in gel films of BaTiO3, LiNbO3 and LiTaO3 was not observed although the laser beams were absorbed in the films. These sol-gel films were thermally crystallized at almost the same temperature around 600–700°C except TiO2. Thus, the UV-laser-induced crystallization is not directly ascribed to a simple thermal effect with the irradiation. Photochemical properties of the cations are assumed to be important for the change in sol-gel films. 相似文献
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28.
Our third generation synthesis of Tamiflu was achieved in 12 steps from commercially available starting materials, using the Diels-Alder reaction and Curtius rearrangement as key steps. 相似文献
29.
Eiji Ihara Takao Wake Naoki Mokume Tomomichi Itoh Kenzo Inoue 《Journal of polymer science. Part A, Polymer chemistry》2006,44(19):5661-5671
α,α‐Dibromotoluene 1 was found to be polymerized by the reaction with excess Mg to give poly(phenylmethylene)s 2 , whose main chains were partially dehydrogenated to carbon–carbon double bonds (C?C). The C?Cs in 2 can be brominated by treatment with Br2. The polymerization mechanism was presumed to include the formation of Grignard reagents of various species with benzylic C? Br bonds and the nucleophilic attacks of the Grignard reagents to various compounds with benzylic C? Br bonds. Copolymerization of 1 with dichlorodimethylsilane successfully proceeded. Mg/Cu‐mediated copolycondensation of 1 with 1,6‐dibromohexane proceeded to give polymers that have similar compositions to those of random copolymers of ethylene and styrene. © 2006Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5661–5671, 2006 相似文献
30.
H. Toki 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):177-180
We critically review the present relativistic mean-field theory from the viewpoint of missing pions. We introduce the interesting
experimental data on pionic states taken at RCNP. These data seem to suggest the occurrence of pion condensation in the nuclear
surface. Qualitative discussion is made on the consequence of surface pion condensation on Gamow-Teller transitions and spin
response functions and others. The radioactive ion beams are the tools of studying the unstable nuclei, which have extended
nuclear surfaces. We shall start with radioactive ion beams the nuclear surface science, which includes the surface pion condensation
as the important ingredient in addition to spin-orbit splitting and surface pairing.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献