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Volume 61, Issue 4
Displaying 1-10 of 10 articles from this issue
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Akikazu MATSUMOTO, Toshihiro TANAKA, Sadamu NAGAHAMA2004 Volume 61 Issue 4 Pages 203-215
Published: April 25, 2004
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSWe have reported some examples of topochemical polymerization and the application to polymer crystal engineering using 1, 3-diene monomers such as muconic and sorbic acid derivatives as the esters, amides, or ammonium salts. The monomer stacking structure is controlled by supramolecular synthons. The formation of two-dimensional hydrogen bond networks and CH/π interaction take especially important roles for a translational and alternate stacking, leading to the formation of diisotactic and disyndiotactic polymers, respectively. We recently reported the first synthesis of disyndiotactic 1, 3-diene polymers using the topochemical polymerization of di (4-alkoxybenzyl) (Z, Z) -and (E, E) -muconates. Furthermore, we also found the polymerization of (E, Z) -muconate derivatives with the feature of translational and alternate molecular stacking according to the structure of the ester and N-substituents. Consequently, four kinds of stereoregular polymers have been produced by the polymerization of the (Z, Z) -, (E, E) -, and (E, Z) -muconates as the ester and ammonium derivatives. The weak and flexible intermolecular interactions give a variety of crystal structures and different types of the molecular stacking leading to the different tacticities of polymers. In this review article, we discuss the synthesis of diisotactic and disyndiotactic polymers, as well as the structure, properties, and reactions of the stereoregular diene polymers.View full abstractDownload PDF (2947K) -
Tsutomu OISHI, Yong-kyung LEE, Kenjiro ONIMURA2004 Volume 61 Issue 4 Pages 216-226
Published: April 25, 2004
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSChiral methacrylates (RMOC, RMOU) having an urethane or urea bond were synthesized from the reaction of 2-methacryloyloxyethyl isocyanate (MOI) and optically active alcohols or amines, such as cholesterol, L-menthol, amino acid derivatives, cinchonine, (S) methylbenzylamine, (R) -1- (1-naphthyl) ethylamine, and so on. Radical polymerizations of RMOC and RMOU were carried out using azobisisobutyronitrile (AIBN) to obtain corresponding optically active polymers having hydrogen bonds caused by urethane or urea segments. Chiroptical properties of poly (RMOC) and poly (RMOU) were affected by temperature. This may be attributed to change of conformation caused by hydrogen bonds and/or interaction between substituents in the side chain. From the results of radical copolymerizations of RMOC or RMOU with styrene (ST), methyl methacrylate (MMA), or butyl methacrylate (BMA), monomer reactivity ratios (r1, r2) and Alfrey-Price Q-e were determined. Chiroptical properties of the copolymers were strongly influenced by comonomer units. To examine chiral recognition abilities of poly (RMOC) and poly (RMOU), chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC) were prepared from silica gel, poly (RMOC), and poly (RMOU). The CSPs resolved racemates 1 to 16, and the chiral recognition abilities of poly (RMOC) and poly (RMOU) may be ascribed to the secondary and/or higher-ordered structure of the polymers.View full abstractDownload PDF (1970K) -
Shigeru YAMAGO, Kazunori IIDA, Mitsuru NAKAJIMA, Jun-ichi YOSHIDA2004 Volume 61 Issue 4 Pages 227-236
Published: April 25, 2004
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSOrganotellurium-mediated living radical polymerization (TERP) has been developed. Polymer-end mimetic organotellurium compounds serve as highly efficient initiators for living radical polymerization that allows accurate molecular weight control with defined endgroups. Addition of AIBN dramatically accelerates the rate of the polymerization with keeping a high level of molecular weight controllability. The polymerization with AIBN completed within 2-11h at 60°C, while that without AIBN required 12-24h at 80-105°C for completion. Not only purified organotellurium compounds but also in situ generated ones from shelf-stable AIBN and ditellurides can be used for living radical polymerization. A variety of monomers including styrene, acrylate, acrylamide, acrylonitrile, and methacrylate derivatives were polymerized to give defined polymers using the same initiators. AB-Diblock, ABA and ABC-triblock copolymers composed of different families of monomers were also synthesized in a highly controlled manner. Transformations of the end-groups via radical and ionic reac-tions provide a variety of end-group modified polymers with defined structures with various functional groups.View full abstractDownload PDF (1993K) -
Atsushi KAJIWARA2004 Volume 61 Issue 4 Pages 237-249
Published: April 25, 2004
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSRadical precursors of poly (meth) acrylates with given chain lengths were prepared by atom transfer radical polymerization (ATRP) technique. Model radicals with given chain lengths were generated by reaction of the precursors with organotin compound. The radicals were observed by electron spin resonance (ESR) spectroscopy. ESR spectra of methacrylate model radicals with degrees of polymerizations (Pn) of 30, 50, and 100 were measured. On comparison of these spectra, clear chain length dependence was observed and a detection of polymeric propagating radicals was clearly shown in the conventional radical polymerization. ESR spectra of model radicals of acrylates did not display chain-length dependence. The spectra suggested a formation of significant amounts of mid-chain radicals from acrylate propagating radicals via 1, 5-hydrogen shift. ESR spectra of dimeric model radical of acrylate clearly provided experimental evidence of the 1, 5-hydrogen shift. Dimers of various (meth) acrylate units: methyl acrylate (MA), tert-butyl acrylate (tBA), and methyl methacrylate (MMA), were prepared by ATRA. These dimers provided radicals mimicking the active species in a radical copolymerization of MA, MMA and tBA. Well-resolved ESR spectra of the dimeric radicals confirm electronic and steric effects of the penultimate unit on the propagating radical.View full abstractDownload PDF (2530K) -
Hiroharu AJIRO, Osamu IKESHIMA, Shigeki HABAUE, Yoshio OKAMOTO2004 Volume 61 Issue 4 Pages 250-255
Published: April 25, 2004
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSThe commercially available macroporous silica gels (Daisogel SP-1000, particle diameter 7μm, pore size 1000Å) were utilized as a starting material for the atom transfer radical polymerization, and the silica gels grafted by polystyrene, poly (methyl methacrylate), and poly (2-hydroxyethyl methacrylate) were effectively synthesized using copper chloride/N, N, N′, N″, N″-pentamethyldiethylenetriamine or N- (n-propyl) -2-pyridylmethanimine complex. The amount of the immobilized polymers and the surface area of the obtained gels were facilely controllable by changing the polymerization time. These results were confirmed by BET experiments, SEM, and TG measurements. Various gels bearing the surface areas from 25.0 to 0.99m2/g were synthesized by immobilization of 1.3-2.5g of polymers to one g of silica gel.View full abstractDownload PDF (1757K) -
Shinya HAMASAKI, Tsuyoshi ANDO, Masami KAMIGAITO, Mitsuo SAWAMOTO2004 Volume 61 Issue 4 Pages 256-262
Published: April 25, 2004
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSA series of metal alkoxides [M (Oi-Pr) n (M=Al, Sn, Ti, Zr, Sc) and Ti (OR) 4 (R=Me, Et, i-Pr, t-Bu, Ph) ] were examined as additives for rate enhancement and finer reaction control in the living radical polymerization of methyl methacrylate (MMA) with RuCl2 (PPh3) 3. All the additives induced a faster polymerization than in their absence and gave polymers with controlled molecular weights and narrow molecular weight distributions (MWDs) (Mw/Mn=1.1-1.3). Ti (Oi-Pr) 4 was the most effective in terms of the rate and the controllability and was effective in the synthesis of a high molecular weight polymer with a narrow MWD (Mn=100900, Mw/Mn=1.11). 1H NMR analysis showed that the added titanium alkoxide interacted with RuCl2 (PPh3) 3 to generate a more active catalyst.View full abstractDownload PDF (1489K) -
Shuji KAWAGUCHI, Yukihiro MITSUDA, Takahiro UNO, Masataka KUBO, Takahi ...2004 Volume 61 Issue 4 Pages 263-268
Published: April 25, 2004
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSSpontaneous polymerization of 7, 7-dicyanobenzoquinone methide (CQM) with 1, 3-cyclohexadiene (CHD) was investigated. The spontaneous reactions gave alternating copolymers of CQM with CHD, where CHD units were incorporated in 1, 2 and 1, 4-addition structures, as hexane-insoluble products and a Diels-Alder adduct of CQM with CHD as hexane-soluble product. Addition of acetic acid to the spontaneous polymerization system did not affect the composition and distribution of products. On the other hand, the spontaneous polymerization in the presence of 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO) gave a low molecular weight alternating copolymer with TEMPO at the terminal end as hexane-insoluble product and a 1: 1: 1 adduct as hexane-soluble product. It was concluded from these results that the spontaneous polymerization of CQM with CHD proceeds via a diradical intermediate.View full abstractDownload PDF (1182K) -
Masashi TSUJI, Ryosuke SAKAI, Towako AOKI, Toshifumi SATOH, Harumi KAG ...2004 Volume 61 Issue 4 Pages 269-274
Published: April 25, 2004
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSThe enantiomer-selective radical polymerization of rac-2, 4-pentanediyl dimethacrylate (rac-1) was carried out using methyly 2-bromoisobutylate (3) / Ru catalyst (Ru-X) / chiral additive (A-X) as the chiral atom transfer radical polymerization (ATRP) initiating systern in anisole at 60°C. The chiral metal complex affected the enantiomer selectivity, e. g., when (S) -1, 1′-bi-2-naphthol (A-4) was used as the chiral additive, (2R, 4R) -2, 4-pentanediyl dimethacrylate (RR-1) was predominantly consumed and the enantiomeric excess of the recovered monomer was 16.9% at 22.6% of a monomer conversion. The enantiomeric excess of the recovered monomer increased with the increasing monomer conversion, and the specific rotation of the resulting polymers decreased. In conclusion, we achieved the enantiomerselective polymerization by cyclopolymerizing rac-1 by the ATRP method using the chiral initiating system.View full abstractDownload PDF (1212K) -
Bunichiro YAMADA, Kentarou INOUE2004 Volume 61 Issue 4 Pages 275-281
Published: April 25, 2004
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSThe α-methylstyrene unsaturated dimer (2, 4-diphenyl-4-methyl-1-pentene, MSD) was used for photosensitized styrene (St) polymerization at 30-130°C. The adduct radical formed from MSD was detected by ESR spectroscopy to monitor the after effect. The rate constants (kt) for mutual reaction of the adduct radical were calculated from the decay curves. The kt values at 100°C or above deviated from the linear relationship obtained by the Arrhenius plot at lower temperatures. The adduct radical was considered to react mutually and to undergo β-fragmentation. The chain transfer constant of MSD at 100 and 130°C were 0.26 and 0.46, respectively. A kinetic equation consisting of the terms of bimolecular reaction and β-fragmentation was derived and the rate constants for these reactions were estimated at different temperatures. Chain transfer constants of MSD were calculated from the Mayo equation: 0.26 and 0.46 at 100 and 130°C, respectively. It was predicted that MSD acts as an effective chain transfer agent in styrene polymerization to reduce molecular weight and to introduce the 2-phenyl-2-propenyl end group competing with addition of the adduct radical to styrene over the temperature range examined. More significant acceleration of the β-fragmentation with increasing temperature than the mutual reaction results in higher chain transfer reactivity of MSD at higher temperatures. MSD also act as an effective AFCT agent in methyl methacrylate polymerizationView full abstractDownload PDF (1376K) -
Tamaki NAKANO, Tohru YADE2004 Volume 61 Issue 4 Pages 282-288
Published: April 25, 2004
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSAsymmetric radical polymerization of N-cyclohexylmaleimide was attempted using α, α′-azobisisobutyronitrile (AIBN) as an initiator and (R, R) -N, N′-bis (3, 5-di-tert-butylsalicylidene) -1, 2-cyclohexanediaminatocobalt (II) (1) as an optically active additive in a tetrahydrofuran-pyridine mixture and in pure tetrahydrofuran: the reaction was only inhibited by the cobalt complex. However, it was found that introduction of a small amount of O2 or air to the inhibited reaction system in tetrahydrofuran-pyridine effectively promoted polymerization, and AIBN was not necessary to achieve the polymerization. O2 or air did not promote polymerization in pure tetrahydrofuran. A reaction mechanism involving an anionic propagating species was proposed; interaction of 1-O2 complex with the monomer caused electron transfer from the former to the latter, generating an anionic species in which coordination of pyridine to Co seems to be indispensable. The polymers obtained in the 1-O2-monomer systems were optically active, based on a chiral main-chain configuration.View full abstractDownload PDF (1331K)
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