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Y. Ohsumi T. Higashimura S. Okamura 《Journal of polymer science. Part A, Polymer chemistry》1967,5(4):849-862
Methyl vinyl ether (MVE) was polymerized under various conditions by BF3·O(C2H5)2 and SnCl4·CCl3CO2H catalysts. The effect of polymerization conditions on the steric structure of poly(methyl vinyl ether) (PMVE) was studied by NMR spectra. It was found that the triad isotacticity of PMVE decreased and the syndiotacticity and heterotacticity increased with increasing polarity of the solvent and increasing polymerization temperature. This result coincided with the qualitative conclusion estimated from softening point and infrared spectra. However, the variation of tacticity by the change of the polarity of a solvent was not so large as expected. There was no large difference between the behavior of BF3·O(C2H5)2 and SnCl4·CCl3CO2H as catalysts. From the relation between the difference of free energy of monomer addition due to the steric structure of the polymer and the polymerization temperature, it was concluded that the penultimate effect really existed and was due to only the difference in enthalpy in the MVE–BF3. O(C2H5)2 or MVE–SnCl4·CCl3CO2H systems. The penultimate effect was not greatly changed by the polymerization conditions in these systems. 相似文献
3.
Shin-ichi Hirano Toshinobu Yogo Wataru Sakamoto Seiji Yamada Tomoyuki Nakamura Tomoe Yamammto Hiroyuki Ukai Kouichi Banno Tomoko Nakafuku Yukari Ando 《Journal of Sol-Gel Science and Technology》2003,26(1-3):35-41
Nano sized crystalline particles/polymer hybrids were synthesized form designed metal-organic precursors. The newly developed method is composed of the synthesis of organic matrix by polymerization and the in situ nucleation and growth of crystalline oxide particles in the organic matrix below 100°C. The design of metal-organic precursor modified with polymerizable ligand and the selection of reaction conditions does influence the size and crystallinity of ceramic particles in organic matrix. The nano-sized magnetic particle/polymer hybrid exhibits the interesting feature of superparamagnetism and quantum size effect. The crystalline particles of BaTiO3/, PbTiO3/, and KNbO3/polymer hybrids behave to be dielectric and show the typical electro-rheological behavior. 相似文献
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Shin-Ichi Hirano Toshinobu Yogo Ko-Ichi Kikuta Wataru Sakamoto 《Journal of Sol-Gel Science and Technology》1994,2(1-3):329-334
The sol-gel processing is one of promising methods to fabricate well-derived integrated thin films at relatively low temperature. Ferroelectric niobates films do afford the possibilities for adding the values by the hybridization with semiconductor and/or electro-optic systems. The molecular level designing of the precursor solution was stressed as well as the control of key processing factors. The advantages of this sol-gel have been extended to prepare the ferroelectric Pb(Mg, Nb)O3-PbTiO3 solid solution films integrated on Si wafers. The crystallization of the films with desired crystal structure could be promoted by the controlled partial hydrolysis of designed alkoxide solution in the intermediate state and the pre-heated treatment of alkoxide-derived films in flow of water vapor and oxygen gas mixture. 相似文献
6.
Toshinobu Suzuki Nobuhiro Katou Keiryo Mitsuhashi 《Journal of heterocyclic chemistry》1978,15(8):1451-1453
Some diaminopyridazines such as 4,7-diaminoimidazo[4,5-d]pyridazine, 1-methyl-4,7-diaminoimidazo[4,5-d]pyridazine, 5,8-diaminopyrazino[2,3-d]pyridazine, 2,3-dimethyl-5,8-diaminopyrazino[2,3-d]pyridazine and 1,4-diaminophthalazine, all of which were prepared by the reaction of hydrazine with the respective vic-dicyanide as starting material, were reacted with benzoyl chloride in the presence of triethylamine, giving novel perbenzoylated derivatives in good yield. A dibenzoylation mechanism of the amino group has been proposed. 相似文献
7.
Toshinobu Korenaga 《Journal of fluorine chemistry》2007,128(5):557-561
A pentafluorophenyl group can act as a stereo-controlling group in oxazaborolidine-catalyzed asymmetric borane reduction through intramolecular π-π stacking interaction with a phenyl group. The intramolecular π-π interaction in oxazaborolidine bearing pentafluorophenyl group is confirmed by calculations and 1H NMR study. The interaction affects the enantioselectivity of the asymmetric reduction of acetophenone while the extent is small. 相似文献
8.
Tamotsu Hashimoto Mitsuo Sawamoto Toshinobu Higashimura 《Journal of polymer science. Part A, Polymer chemistry》1987,25(10):2827-2838
p-Vinylphenyl glycidyl ether (VPGE), a styrene derivative with an epoxy pendant, was polymerized by various cationic initiators, and its selective vinyl polymerization was investigated at low temperatures below ?15°C. BF3OEt2 (a metal halide) and CF3SO3H (a strong protonic acid) polymerized both vinyl and epoxy groups of VPGE, and produced cross-linked insoluble polymers. The HI/I2 initiating system and iodine, in contrast, polymerized its vinyl group in polar solvents (CH2Cl2 and nitroethane) highly selectively in the temperature range of ?15 to ?40°C to give soluble polymers with a polystyrene backbone and epoxy pendants; however, under these conditions, 10–15% of the epoxy groups of the polymers were consumed during the polymerization by the reaction with the growing species. The polymerization by HI/I2 in CH2CI2 involved a long-lived propagating species, as indicated by a progressive increase in the molecular weight (M?n) of the polymers with monomer conversion and their fairly narrow molecular weight distributions (M?w/M?n ~ 1.6). The differences between the polymerizations of VPGE and p-isopropenylphenyl glycidyl ether, an α-methylstyrene-type counterpart of VPGE, were also discussed with an emphasis on the effects of the α-methyl group in the latter monomer. 相似文献
9.
T. Higashimura S. Kusudo Y. Ohsumi S. Okamura 《Journal of polymer science. Part A, Polymer chemistry》1968,6(9):2523-2531
To elucidate the effect of the introduction of a methyl group in the β-position of a vinyl monomer, propenyl alkyl ethers were copolymerized with vinyl ethers having the same alkoxy group. Propenyl alkyl ethers with an unbranched alkoxy group (ethyl or n-butyl propenyl ether) were more reactive than the corresponding vinyl ethers. This behavior is quite different from that of β-methylstyrene derivatives. However, propenyl alkyl ethers with branched alkoxy groups at the α carbon atom (isopropyl or tert-butyl propenyl ether) were less reactive than the corresponding vinyl ethers. Also, cis- isomers were more reactive than the trans isomers, regardless of the kind of alkoxy group and the polarity of the solvent. 相似文献
10.
Akio Tanizaki Mitsuo Sawamoto Toshinobu Higashimura 《Journal of polymer science. Part A, Polymer chemistry》1986,24(1):87-96
The cationic polymerization of p-methylstyrene initiated by acetyl perchlorate at ?78°C led to long-lived (living-like) polymers with a narrow molecular weight distribution (M?w/M?n = 1.1–1.4) in methylene chloride containing a common ion salt (n-Bu4NClO4) or in a less polar solvent (CH2Cl2/toluene, 1/4v/v). Under these conditions, the number-average molecular weight (M?n) of the polymers increased in proportion to monomer conversion and was regulated by the monomer-to-initiator ratio. When fresh feeds of the monomer were repeatedly added to a completely polymerized solution, the polymerization ensued at the same rate as before and the linear increase in M?n with monomer conversion continued. The effects of solvent polarity and the common ion salt on the polymerization showed the suppression of the ionic dissociation of the propagating species, resulting in a “nondissociated species,” to be the key factor for the formation of the long-lived polymers. 相似文献