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Naoto Aoyagi Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2019,57(24):2606-2615
The bicyclic amidinium iodide effectively catalyzed the reaction of carbon dioxide and the epoxy‐containing oxetane under ordinary pressure and mild conditions with high chemoselectivity to give the corresponding oxetane monomer containing five‐membered cyclic carbonate quantitatively. The cationic ring‐opening polymerization of the obtained monomer by boron trifluoride diethyl ether proceeded to give linear polyoxetane bearing five‐membered cyclic carbonate pendant group in high yield. The molecular weight of the polyoxetane was higher than that of polyepoxide obtained by the cationic ring‐opening polymerization of epoxide monomer containing five‐membered cyclic carbonate. The cyclic carbonate functional crosslinked polyoxetanes were also synthesized by the cationic ring‐opening copolymerization of cyclic carbonate having oxetane and commercially available bisoxetane monomers. Analyses of the resulting polyoxetanes were performed by proton nuclear magnetic resonance, size exclusion chromatography, thermogravimetric analysis, and differential scanning calorimetry. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2606–2615 相似文献
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Naoto Aoyagi Yoshio Furusho Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2013,51(5):1230-1242
Hydroiodides of secondary and primary amines effectively catalyzed the reaction of carbon dioxide and epoxides under mild conditions such as ordinary pressure and ambient temperature, to obtain the corresponding five‐membered cyclic carbonates in moderate to high yields. Detailed investigation showed that the catalytic activity was highly affected by the counter anions of the ammonium salts; the iodides catalyzed efficiently the carbonate‐forming reactions, whereas the bromide and chloride counterparts exhibited almost no catalysis. We also revealed that two important factors on the amine moieties that affected the catalytic reactions. First, the catalytic activity increased with increasing bulkiness of the substituents on the ammonium nitrogen atoms. Second, the catalysis became more efficient as the parent amines become more basic. Dicyclohexylammonium iodide was the best catalyst among the ammonium salts investigated in this study. As an application of this reaction system, we synthesized homo‐ and copolymers bearing epoxide pendant groups as substrates, which were converted with high efficiency into the corresponding homo‐ and copolymers bearing cyclic carbonate pendant groups under 1 atm at 45 °C. All polymers were easily purified simply by precipitation in water, and were isolated in high yields (>95%). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
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Energy dependence of proton-nucleus reaction cross section at very high energy is discussed. It is stressed that depending
on the gluon distribution near the nuclear surface, proton-nucleous total cross section increases much more rapidly compared
to the usual Glauber independent nucleon estimate. The recent observation of smaller X
max than the expected value at UHECR domain can be an indication for such a mechanism. 相似文献
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Takeshi Yamanobe Tadashi Komoto Yoshiko Sakaino 《Molecular Crystals and Liquid Crystals》2013,570(1-2):273-282
Abstract Solid state NMR measurements are carried out for polymorphs and inclusion complexes of 4,5-bis(4-methoxyphenyl)-2-(3-nitrophenyl)-1H-imidazole. Observed 13C and 15N chemical shifts are characteristic of each polymorph A, B, C and D. In addition, 15N chemical shift was a good index for understanding hydrogen bond. VT measurements revealed that B transforms to C between 93 and 113°C. From PSTMAS and 1H solid echo measurements for AcOET inclusion complex, host molecules have almost same structure as B and guest molecules have the highest mobility of all inclusion complexes. 相似文献
1000.
Yinghan Wang Chunying Xu Akihiko Kanazawa Takeshi Shiono Tomiki Ikeda Yasuo Matsuki 《Liquid crystals》2013,40(3):473-475
The thermal stability of alignment of a nematic liquid crystal (LC) on three polyimide (PI) films exposed to linearly polarized light at 366 nm was investigated. Polarizing optical microscopy analysis indicates that the thermal stability of the LC alignment on the PI film without significant structural change was higher than that with obvious structural change. 相似文献