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排序方式: 共有196条查询结果,搜索用时 31 毫秒
31.
Fumio Sanda Taizo Fujiyama Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2001,39(5):732-741
α‐Methyl glutamic acid (L ‐L )‐, (L ‐D )‐, (D ‐L )‐, and (D ‐D )‐γ‐dimers were synthesized from L ‐ and D ‐glutamic acids, and the obtained dimers were subjected to polycondensation with 1‐(3‐dimethylaminopropyl)‐3‐ethylcarbodiimide hydrochloride and 1‐hydroxybenzotriazole hydrate as condensation reagents. Poly‐γ‐glutamic acid (γ‐PGA) methyl ester with the number‐average molecular weights of 5000∼20,000 were obtained by polycondensation in N,N‐dimethylformamide in 44∼91% yields. The polycondensation of (L ‐L )‐ and (D ‐D )‐dimers afforded the polymers with much larger |[α]D | compared with the corresponding dimers. The polymer could be transformed into γ‐PGA by alkaline hydrolysis or transesterification into α‐benzyl ester followed by hydrogenation. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 732–741, 2001 相似文献
32.
Fumio Sanda Tsuyoshi Shinjo Wonmun Choi Takeshi Endo 《Macromolecular rapid communications》2001,22(5):363-366
This article deals with the cationic and anionic depolymerization of polydithiocarbonate, which was synthesized by cationic polymerization of 5‐phenoxymethyl‐1,3‐oxathiolane‐2‐thione ( 1 ) using methyl triflate as the initiator. The cationic depolymerization of the obtained polymer was carried out in the presence of 5–20 mol‐% of methyl triflate or triflic acid catalyst in chlorobenzene at 60 °C for 96 h to afford 4‐phenoxymethyl‐1,3‐dithiolan‐2‐one ( 2 ) in 35–83% yield. The anionic depolymerization of the polymer was carried out in the presence of 5 mol‐% of triethylamine or potassium tert‐butoxide at 20 °C for 24 h to afford 2 in 85–100% yield. 相似文献
33.
Alexander Steblyanko Wonmun Choi Fumio Sanda Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2000,38(13):2375-2380
A bifunctional five‐membered cyclic carbonate was synthesized from carbon dioxide and diglycidyl terephthalate, and its polyaddition with alkyl diamines were carried out in DMF at room temperature to obtain the corresponding poly(hydroxyurethane)s with Mn s in the range of 6300–13200 in good yields. The structures of the obtained polymers were confirmed by IR and NMR spectroscopy and their glass‐transition and decomposition temperatures were observed at 3–29 °C and 182–277 °C, respectively. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2375–2380, 2000 相似文献
34.
Manabu Kirino Fumio Sanda Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2000,38(18):3428-3433
Novel aliphatic aminimides were synthesized from the corresponding carboxylic acid esters, 1,1‐dimethylhydrazine, and epoxides in 54–95% yields. Bulk polymerization of glycidyl phenyl ether (GPE) with 3 mol % of the aminimides was evaluated by DSC as a model process for curing of epoxy resin. All the aminimides showed no exothermic DSC peak below 120 °C but showed sharp exothermic peaks above 137 °C, indicating good thermal latency. Good relationships were observed between the calculated bond length from the carbonyl carbon to the α‐carbon of the aliphatic group (R C), DSC onset temperatures, and the thermal dissociation temperatures (Td 's) of the aminimides. The aminimide with a longer R C bond length showed lower Td and DSC onset temperature, that is, higher activity. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3428–3433, 2000 相似文献
35.
36.
Toshikazu Takata Fumio Sanda Toshiro Ariga Hideo Nemoto Takeshi Endo 《Macromolecular rapid communications》1997,18(6):461-469
A variety of cyclic carbonates was shown to undergo volume expansion on polymerization. The degree of volume expansion, which was measured by the density gradient tube method, was ranging from 1.1% to 7.7%. The volume expansion was examined by assuming a change in molecular interaction such as dipole moment between monomer and polymer states. 相似文献
37.
Natsuhiro Azuma Fumio Sanda Toshikazu Takata Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1997,35(17):3673-3682
Cationic ring-opening polymerization behavior of a seven-membered cyclic sulfite ( 1 ) was examined. 1 was prepared by the reaction of 1,4-butanediol with SOCl2 in 58% yield. The cationic polymerization of 1 was carried out at 0, 25, 60, or 100°C with trifluoromethanesulfonic acid (TfOH), methyl trifluoromethanesulfonate (TfOMe), BF3 · OEt2, SnCl4, methyl p-toluenesulfonate (TsOMe), or MeI as an initiator in bulk under a nitrogen atmosphere to afford the polymer with M̄n 1000–10,400. The order of activities of the initiators for 1 was as follows, TfOH ≅ TfOMe > SnCl4 > BF3 · OEt2 > TsOMe ≅ MeI. The polymerization of 1 with TfOMe afforded a poly(sulfite) below 25°C, but afforded a polymer containing an ether unit at 60°C, which was formed by a desulfoxylation. The higher the activity of the initiator was, the more easily the desulfoxylation occurred. We expected volume expansion on polymerization because cyclic sulfites have large dipole moment values, but it turned out that 1 showed 4.34% shrinkage on polymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3673–3682, 1997 相似文献
38.
Emiko Koyama Fumio Sanda Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1997,35(14):2925-2934
Polycondensations of dicarboxylic acids with diols having amide moieties derived from optically active amino alcohols were carried out. Polymers with M ns 8,700–17,400 were obtained by the polycondensations using 1.2 eq. of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC·HCl) in DMF at room temperature for 8 h in satisfactory yields. The Tg of the polymer rose with decrease of the methylene chain length of the dicarboxylic acid. In the Tgs of the polymers from L-leucinol, even-odd effect was observed with increase of the methylene chain length of the dicarboxylic acid. The molecular rotation values of the polymers were constant except for the polymer from succinic acid, which showed the negatively largest one. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2925–2934, 1997 相似文献
39.
40.
Sang‐Do Lee Fumio Sanda Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1999,37(7):1041-1048
Graft polymerization of glycidyl phenyl ether (GPE) and alternating graft copolymerization of GPE–succinic anhydride (SA) onto a polymer‐supported aminimide were examined. The polymer‐supported aminimide was synthesized by radical polymerization of 1,1‐dimethyl‐1‐(2‐hydroxy‐3‐(4‐vinylbenzyloxy)propyl)amine 2‐benzoylimide, which was prepared by the reaction of methyl benzoate with equimolar amounts of 1,1‐dimethyl hydrazine and 4‐glycidylmethylstyrene. This aminimide could initiate the polymerization of GPE and alternating copolymerization of GPE with SA to give the corresponding graft copolymers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1041–1048, 1999 相似文献