Coexistence of Active Species in Anionic Polymerization of Ethyl Methacrylate by Butyllithium

Hatäda, Koichi; Kitayama, Tatsuki; Sugino, Hikaru; Umemura, Yoshihiro; Furomoto, Mitsuru; Yuki, Heimei

doi:10.1295/polymj.11.989

Cited by 11 publications

(7 citation statements)

References 9 publications

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“…Carbonyl attack by the initiator occurs more largely in the polymerization with n-C4H9Li of MMA than in that of t-BuMA (Hatada et al, 1979(Hatada et al, ,1982. Cross-linking by the association of the PMMA branches, like stereocomplex formation, could be another possible explanation.…”

Section: Resultsmentioning

confidence: 99%

Syntheses and applications of graft copolymers from poly(1,1-diphenylethylene-co-divinylbenzene)s

Hatäda¹,

Kitayama²,

Sasaki³

et al. 1986

Ind. Eng. Chem. Prod. Res. Dev.

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Anionic copolymerization of 1, ldiphenylethylene and rn-and p divinylbenzenes gave soluble copolymers having pendant vinyl groups when an excess amount of 1,ldiphenylethylene over divinylbenzenes was used. The copolymers hardly formed cross-linked polymers, as compared with the homopolymers of divinylbenzenes, and were easlly converted to polymer anions by adding sec-butyllithlum in THF at -78 "C. The anions were reacted with several methacrylates or other vinyl monomers to give the graft copolymers with the corresponding polymer branches. The number of branches could be controlled by partially quenching the completely anionized copolymer with a certain amount of methanol before the addition of the monomers or by changing the amount of sec-butyllithium. Practical applications of the graft copolymers to polymeric emulsifier and negative electron-beam resist were examined.

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Section: Resultsmentioning

confidence: 99%

Syntheses and applications of graft copolymers from poly(1,1-diphenylethylene-co-divinylbenzene)s

Hatäda¹,

Kitayama²,

Sasaki³

et al. 1986

Ind. Eng. Chem. Prod. Res. Dev.

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“…The polymerization of EMA with 1,1-diphenylhexyllithium gave no syndiotactic polymer, while the amount of lithium ethoxide formed in this system was zero. 3 These results suggest that the lithium ethoxide formed in the initial stage of the polymerization is closely related to the formation of the active species which produce syndiotactic polymers. The active species for syndiotactic fraction may exist in the form of ion pairs complexed with lithium ethoxide molecules, while the isotactic active species are free from them.…”

Section: Coexistence Of Multiple Active Speciesmentioning

confidence: 88%

“…In the previous paper, 3 we suggested the existence of at least three types of active species in the polymerization of EMA with BuLi: the active species for the syndiotactic and isotactic polymers and that for the oligomer. The formation of these active species is related to lithium ethoxide but it has not been clear as to how the oligomer chain forms at the early stage of polymerization and how the dormant species of the oligomeric anions sometimes awaken to form polymeric anions.…”

Section: Polymerization Mechanismmentioning

confidence: 94%

“…The polymerization of ethyl methacrylate (EMA) with BuLi in toluene gives methanol-soluble and -insoluble fractions. 3 The methanol-insoluble fraction was found to consist syndiotactic polymer, and the methanolsoluble fraction to contain the isotactic polymer and the oligomer. These two fractions are easily separated by pouring the polymerization mixture into methanol.…”

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confidence: 97%

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Studies on the Mechanism of Polymerization of Ethyl Methacrylate with BuLi in Toluene Using Perdeuterated Monomer and Multiplicity of Active Species

Hatäda

Kitayama

Okahata

et al. 1982

Polym J

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ABSTRACT:Perdeuterated ethyl methacrylate was polymerized with BuLi in toluene at -78°C. The resulting product consisted of syndiotactic and isotactic polymers and oligomers, indicating the existence of multiple active species. The structure of each component was confirmed by 1 H NMR spectroscopy. Most of the oligomers had butyl isopropenyl ketone units at the chain ends. The isotactic polymer contained one ketone unit near the beginning of the chain, while the syndiotactic polymer had about two ketone units located near the beginning and interior sequence of the chain. The mechanism of polymerization is discussed in detail, and also the structures of active species are proposed from the standpoint of the association oflithium alkoxide formed in the system, that is, the syndiotactic active species are associated with the alkoxide while the isotactic species are not.KEY In the anionic polymerizations of some a-substituted acrylates with butyllithium (BuLi), it was confirmed that isotactic and syndiotactic polymers are formed independently in the same reaction system. 1 -3 This suggests the existence of multiple active species in the polymerization. The polymerization of ethyl methacrylate (EMA) with BuLi in toluene gives methanol-soluble and -insoluble fractions.3 The methanol-insoluble fraction was found to consist syndiotactic polymer, and the methanolsoluble fraction to contain the isotactic polymer and the oligomer. These two fractions are easily separated by pouring the polymerization mixture into methanol. No syndiotactic polymer was obtained when the polymerization temperature was above -20°C or 1,1-diphenylhexyllithium was used as an initiator instead of BuLi. These results were explained in terms of the multiplicity of active species.3 However, the difference in structure other than tacticity among the syndiotactic and isotactic polymers and oligomers was not clear.Recently we have developed a new method for studying the polymerization reaction, in which the perdeuterated monomer is polymerized with an undeuterated initiator and the product is analyzed by 1 H NMR spectroscopy. 4 -8 The study on the anionic polymerization of methyl methacrylate (MMA) with BuLi in toluene 4 and in tetrahydrofuran (THF) 5 by the perdeuterated monomer technique revealed that butyl isopropenyl ketone, formed through the attack of BuLi on the carbonyl double bond of MMA, was incorporated into the polymer and oligomer chains. The manner of incorporation of the ketone unit in the syndiotactic polymer formed in THF differed from the case of the isotactic polymer formed in toluene. These findings lead us to investigate the structural differences in the isotactic and syndiotactic polymers of EMA formed in toluene by the perdeuterated monomer method.In this study, perdeuterated EMA was synthesized and polymerized with BuLi in toluene at 971

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“…The number of experimental variables is the basic reason for the notorious irreproducibility of yields and triad compositions encountered. It is not uncommon for two workers in the same laboratory to prepare different products using the same recipe, and this is not confined to the organomagnesium systems (Yuki and Hatada, 1979). Joint monitoring inevitably reveals the source of the discrepancy, e.g., temperature at which the initiator is filtered , but this is not possible when trying to reproduce old experiments reported in the literature.…”

Section: Homogeneous Solutionmentioning

confidence: 99%

Stereoregulation of methyl methacrylate polymerization

Allen¹,

Williams²

1985

Ind. Eng. Chem. Prod. Res. Dev.

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Stereospecific polymerization of methyl methacrylate (MMA) in solution is a rare example of a homogeneous, highly isotactic-specific, vinyl polymerlzatlon. The mechanism of stereoregulatkm and the optimization of efficient, highly isotactic polymerjzetion by Qlgnard reagents Is discussed in detaH. Insertkn of coordinated monomer, by a &enter transition state, into an Mg-C bond at a sterically protected, chirai, growth site is the basis of the proposed mechanism for isotactic polymerization. A ligand-migration mechanism could explain the few cases where organometallic reagents yield PMMA more syndiotactic than radical initiation at the same temperature. This does not happen with organomagnesium reagents. The nature of stereoblock polymers is discussed with particular reference to the difficutty in characterizing their steric triad distributions. IntroductionIsotactic poly(methy1 methacrylate) (it-PMMA) was f i t synthesised over a quarter of a century ago (Fox et al., 1958; Miller et al., 1958;Nishioka et al., 1960; Goode et al., 1960, and references cited therein). It was soon established that it presented no threat to the conventional atactic product (at-PMMA), no immediate applications emerged, and commercial interest in this novel crystallizable form of PMMA waned.There are nevertheless a number of deficiencies in the performance of at-PMMA. The physical properties of it-PMMA in the amorphous state are very different; most notably the glass-transition, Tgl is 60° lower (Wittman and Kovacs, 1969) and the dimensions of the coiled chain are more extended in solution (Jenkins and Porter, 1982) and, almost certainly, in the amorphous solid state. The crystallizability certainly presents a problem if it-PMMA is to be used as an amorphous material; it is normally lethargic toward spontaneous crystallization, but we find it extremely susceptible to induced crystallization in the presence of organic vapors-methanol in particular. The answer could well lie in blending the two materials. Our tests have shown that the susceptibility of at-PMMA to environmentally induced cracking and crazing is certainly reduced by blending with it-PMMA and the fracturetoughness is enhanced (Truong et al., 1985).Some attention should be given to the syndiotactic triad content (s) of the at-PMMA used in blends. The s-content increases with decreasing temperature of polymerization. Commercial at-PMMA prepared by free-radical initiation at elevated temperatures has an s-content of ca. 0.6. Free-radical initiation at 195 K yields s-contents as high as 0.78 (Bovey, 1960). Syndiotactic st-PMMA forms crystalline stereocomplexes with it-PMMA (Bosscher et d., 1982). We have found that complexing occm in blends In this paper the periodic group notation is in accord with recent actions by IUPAC and ACS nomenclature committees. A and B notation is eliminated because of wide confusion. Groups IA and IIA become groups 1 and 2. The d-transition elements comprise groups 3 through 12, and the p-block elements comprise groups 13 through 18. (Note that ...

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Coexistence of Active Species in Anionic Polymerization of Ethyl Methacrylate by Butyllithium

Cited by 11 publications

References 9 publications

Syntheses and applications of graft copolymers from poly(1,1-diphenylethylene-co-divinylbenzene)s

Syntheses and applications of graft copolymers from poly(1,1-diphenylethylene-co-divinylbenzene)s

Studies on the Mechanism of Polymerization of Ethyl Methacrylate with BuLi in Toluene Using Perdeuterated Monomer and Multiplicity of Active Species

Stereoregulation of methyl methacrylate polymerization

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