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Predecessor
Volume 81, Issue 10
Displaying 1-9 of 9 articles from this issue
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[in Japanese]2008 Volume 81 Issue 10 Pages 399
Published: October 15, 2008
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSDownload PDF (140K) -
Kotohiro NOMURA2008 Volume 81 Issue 10 Pages 400-407
Published: October 15, 2008
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSSelected successful examples for precise synthesis of new polyolefins by coordination insertion polymerization, especially by copolymerization of ethylene with new comonomer (s) using newly designed complex catalysts have been introduced. Efficient copolymerization of ethylene with styrene can be achieved by so called half-titanocene catalysts, and the ligand modification should play an essential key role especially for the efficient styrene incorporation. Efficient introduction of functional group into polyolefins has also been achieved by the (direct) copolymerization using nonbridged half-titanocenes, and a new synthetic strategy for precise, efficient synthesis of polyolefins containing polar functionalities with uniform compositions (as well as with uniform molecular weight distribution) under mild (environmentally benign) conditions can be demonstrated.View full abstractDownload PDF (5351K) -
Shin-ichi TANAKA, Nobuyuki KOMINE, Sanshiro KOMIYA2008 Volume 81 Issue 10 Pages 408-413
Published: October 15, 2008
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSThis review article describes polymerization reactions of olefins and isocyanides and copolymerization of aziridines and carbon monoxide, which are considered to be promoted by cooperative effect of two different transition metal catalysts.View full abstractDownload PDF (4942K) -
Toshiaki SUZUKI, Zhaomin HOU2008 Volume 81 Issue 10 Pages 414-418
Published: October 15, 2008
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSThe cationic rare earth metal alkyl species bearing a bis (phosphine) amide ancillary ligand, generated by treatment of the corresponding dialkyl complexes with one equivalent of a borate compound can serve as an excellent catalyst for the living cis-1, 4 polymerization of both isoprene and butadiene as well as for the living cis-1, 4 copolymerization of isoprene and butadiene. On the other hand, the polymerization of isoprene by the binuclear monocationic monoalkyl species with cyclopentadienyl-phosphide ligands has afforded exclusively isotactic 3, 4-polyisoprene with extremely high regio- and stereoselectivity (3, 4-selectivity: 100%, mmmm>99%). An amidinate-ligated aminobenzylyttrium complex, in combination with [Ph3C] [B(C6F5)4], is an excellent catalyst system for the isospecific 3, 4-polymerization of isoprene, while the regio- and stereoselectivity of this polymerization system can be dramatically switched from 3, 4-isospecific to 1, 4-cis selective by the addition of AlMe3. Cationic rare-earth hydride clusters, which are made by treating the corresponding neutral complexes with a borate activator, show high regio- and stereoselectivity for the polymerization of 1, 3-cyclohexadiene (CHD) to afford soluble crystalline cis-1, 4-linked poly (CHD) unavailable previously. The syndiospecific living copolymerization of styrene with isoprene has been achieved by use of a cationic half-sandwich scandium alkyl catalyst.View full abstractDownload PDF (3138K) -
Daisuke TAKEUCHI, Kohtaro OSAKADA2008 Volume 81 Issue 10 Pages 419-423
Published: October 15, 2008
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSThis article reviews recent papers on polymerization of dienes and methylenecyclopropanes promoted by late transition metal complexes. Pd-diimine complexes catalyze cyclopolymerization of functionalized 1, 6-heptadienes to produce the polymers having five-membered rings in the repeating units, while Fe- and Co-complex catalyzes the polymerization of unsubstituted 1, 6-heptadiene. 1, 6-Octadiene derivative and higher diene monomers also polymerize in the presence of Pd catalyst. Details of the reactions are discussed. Addition polymerization of methylenecyclopropanes by Ni catalyst affords the polymers with unique structures.View full abstractDownload PDF (2762K) -
Kotaro SATOH, Masami KAMIGAITO2008 Volume 81 Issue 10 Pages 424-430
Published: October 15, 2008
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSThis study is directed to the synthesis of a series of well-defined graft copolymers with the controlled lengths of both the backbone and graft chains by the ruthenium-catalyzed living radical polymerization. The backbone polymer was first synthesized by the ruthenium-catalyzed living radical random copolymerization of methyl methacrylate and 2- (trimethylsilyloxy) ethyl methacrylate followed by the in-situ transformation of the silyloxyl group into the ester with a C-Br bond, which resulted in efficient multifunctional macroinitiators for living radical graft copolymerization. The methodology led to the novel controlled architectural copolymers, AxBAx-type block-graft copolymers, which can function as new building blocks for controlled nanostructures based on microphase separation and is different from that of the conventional ABA triblock copolymers. A series of well-defined AxBAx-type block-graft copolymers consisting of soft middle segments (dodecyl methacrylate) and hard outer graft chains (styrene) were synthesized by the ruthenium-catalyzed block and graft polymerizations to exhibit characteristics of a thermoplastic elastomer.View full abstractDownload PDF (10129K) -
Masayuki WAKIOKA, Ryo TAKITA, Fumiyuki OZAWA2008 Volume 81 Issue 10 Pages 431-437
Published: October 15, 2008
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSRecent progress in structure-controlled synthesis of π-conjugated polymers is described. A particular interest is focused on transition-metal-catalyzed polymerization that enables precise control of molecular weights and stereoregularity of polymers. The topics include: (a) chain-growth polycondensation to afford polythiophene, polyphenylene, and polyfluorene; (b) living ring-opening metathesis polymerization to give poly (phenylenevinylene); (c) polyaddition reactions based on stereoselective hydrosilylation and dimerization of alkynes; (d) stereocontrolled synthesis of poly (arylenevinylene)s (PAVs). The unique photochemical properties of PAVs are described.View full abstractDownload PDF (4258K) -
Kiyoo KATO, Yoshifumi ARAKI2008 Volume 81 Issue 10 Pages 438-444
Published: October 15, 2008
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSSeveral properties and performances of diene rubber and thermoplastic elastomer are improved by catalytic hydrogenation. Generally, heat resistance and weatherability are extremely improved, and polarity, crystallinity and molecular mobility, etc. can be varied after hydrogenation.
Homogeneous catalyst is often used for the hydrogenation of the polydiene because of the higher activity than heterogeneous one, into which the polymer diffusion is rate-determining. Homogeneous catalysts for the hydrogenation of polydiene are roughly classified into three types, (1) Ziegler type (organic-Ni, Co), (2) Metallocen type (Ti), (3) Organo-noble metal type (Rh, Pd, Ru). Although the total number of published reports for the hydrogenation catalyst has been a little decreasing in recent these years, the supported-noble metal type (heterogeneous catalyst) is getting popular recently due to the catalyst recyclability.
Titanocene shows high selectivity for the hydrogenation of 1, 2-bond in polybutadiene. Taking advantage of this phenomenon, the selective hydrogenation for rubber and elastomer grade has been developed for the applications of a PP-modification, a pressure sensitive adhesive and a low rolling resistance tire material.View full abstractDownload PDF (4994K) -
[in Japanese]2008 Volume 81 Issue 10 Pages 445-446
Published: October 15, 2008
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSDownload PDF (2281K)
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