Isotactic‐specific radical polymerization of methacrylamides in the presence of Lewis acids

Suito, Yoshikatsu; Isobe, Yutaka; Habaue, Shigeki; Okamoto, Yoshio

doi:10.1002/pola.10337

Cited by 68 publications

(77 citation statements)

References 24 publications

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“…The increase in the isotacticity of the polymer is ascribed to the effective complexation of Y(OTf) 3 with the last two pendant amide groups of the propagating radical and the incoming monomer unit which in turn favors the meso-type addition of the Lewis acid-complexed NIPAM monomer. Similar observations have been reported for the polymerization of acrylamides, 15,16,18,19,22 methacrylamides, [16][17][18][19][20][21] and methacrylates 24 in the presence of bulky lanthanide triflate Lewis acids. The increase in the EBIB concentration from 10 mM to 30 mM (entries 3, 5 and 6) while keeping other conditions the same increases the polymer yield, decreases the molecular weight of the polymer, and increases the polydispersities.…”

Section: Effect Of Solventsupporting

confidence: 68%

See 1 more Smart Citation

Novel Initiating System for the Stereocontrolled Radical Polymerization of Acrylamides: Alkyl Bromide/Rare Earth Metal Triflate System

Ray

Isobe

Habaue

et al. 2004

Polym J

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ABSTRACT:A novel radical initiating system -rare-earth metal triflate [Y(OTf) 3 , Yb(OTf) 3 , Lu(OTf) 3 , Sc(OTf) 3 ] and alkyl halide containing -esters (ethyl 2-bromoisobutyrate and ethyl 2-bromopropionate) or -amide (N,N-dimethyl-2-bromo-2-methylpropanamide) was used for the stereocontrolled radical polymerization of N-isopropylacrylamide (NIPAM). The Lewis acids serve a dual role as the promoter of the radical initiation and the controller of the stereospecific polymerization. The effects of the Lewis acid type and concentration, the initiator type and concentration, solvents, and temperature on the polymerization of NIPAM have been reported. The chain-end structure of the resulting polymer was determined by 1 H NMR. We also extended this initiating system for the polymerization of 1 Recent progresses in controlled radical polymerization 2-5 have widened the scope of the radical initiators, one of which should be an initiating system consisting of an alkyl halide and a late transition metal complex of ruthenium, iron, copper, etc.3 In this system, the initiating radical is born from the alkyl halide due to the metal-mediated cleavage of the carbon-halogen bond. The organic halide is thus regarded as an initiator, which generates an initiating radical species, while the metal complex as a catalyst, which mediates the radical formation via the reversible one-electron redox reaction of the metal center. This transitionmetal catalyzed radical polymerization system originates from a similar metal-catalyzed radical addition reaction as already reported. 6 An alternative way for the generation of the radical species from an alkyl halide is to use a free radical initiator like AIBN and Et 3 B/O 2 together for the halogen abstraction.6 This combination is often employed for the organic synthesis of small and sometimes cyclic compounds in atom-transfer free radical addition. 6 Recent progress in this area concerns the addition of a Lewis acid such as metal triflates [M(OTf) n , M ¼ Sc, Yb, etc.] into the addition reaction between an -halo ester, nitrile, or amide and an olefin in the presence of Et 3 B/O 2 , where the added Lewis acid improves the reactivity of the slow atomtransfer reaction. [7][8][9][10][11][12] The improvement stems from the weakening of the C-Br bond due to the coordination of the Lewis acid to the carbonyl or the nitrile group of the -halo ester, nitrile, or amide compounds. 12-14This results in an increase in both the rate of the addition of the -carbonyl radical to the olefin and also the halogen abstraction by the resulting nucleophilic carbon radical.Quite recently, we have found that the metal triflates also dramatically accelerated the radical polymerization of acrylamides and other meth(acrylic) monomers with AIBN. [15][16][17][18][19][20][21][22] The Lewis acids further affected the stereochemistry of the polymers. Especially, for the acrylamides, highly isotactic polymers were obtained with rare-earth metal triflates. The increase in the rate and the stereoregularity is considered to...

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Section: Effect Of Solventsupporting

confidence: 68%

“…[15][16][17][18][19][20][21][22] The Lewis acids further affected the stereochemistry of the polymers. Especially, for the acrylamides, highly isotactic polymers were obtained with rare-earth metal triflates.…”

Section: -14mentioning

confidence: 99%

Novel Initiating System for the Stereocontrolled Radical Polymerization of Acrylamides: Alkyl Bromide/Rare Earth Metal Triflate System

Ray

Isobe

Habaue

et al. 2004

Polym J

Self Cite

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“…22 One is based on the use of polar solvents, such as bulky fluoroalcohols 23,24 and aprotic solvents, 25 which can interact with the polar substituents of the monomer units such as methacrylates, vinyl esters, and acrylamides to induce syndiospecific radical polymerizations via the steric repulsion. Another method uses Lewis acids, such as magnesium halides 26 and metal triflates, 27,28 which lead to the isospecific radical polymerization of methacrylates and (meth)acrylamides via multiple site coordination to the polymer terminal working catalytically. Thus, either the molecular weight or the tacticity can now be controlled during the radical polymerizations while the simultaneous regulation of both has still been difficult because of the lack of appropriate strategies or methods.…”

Section: Introductionmentioning

confidence: 99%

Stereospecific living radical polymerization for simultaneous control of molecular weight and tacticity

Kamigaito

Satoh

2006

J. Polym. Sci. A Polym. Chem.

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ABSTRACT:The simultaneous control of the molecular weights and the tacticity was attained even during radical polymerization by the judicious combinations of the living/ controlled radical polymerizations based on the fast interconversion between the dormant and active species, and the stereospecific radical polymerizations mediated by the added Lewis acids or polar solvents via the coordination to the monomer/polymer terminal substituents. This can be useful for various monomers including not only conjugated monomers, such as acrylamides and methacrylates, but also nonconjugated ones such as vinyl acetate and Nvinylpyrrolidone. Stereoblock polymers were easily obtained by the addition of the Lewis acids or by change of the solvents during the living radical polymerizations.

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“…N,N-dietylacrylamide was kindly provided by Kojin and purified by distillation under reduced pressure. The polymerizations were carried out in the absence or presence of Yttrium(III) trifluoromethanesulfonate (Y(OTf) 3 Lewis acid) [12,16]. Chemical structures of PNEAm and PNdEAm were shown in figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…The weight-average molecular weight (M w ) and polydispersity (M w /M n ) were determined by a size exclusion chromatography. The m content was determined by 1 H NMR [12,16,17]. The cloud point (T c ) of a 1 wt % aqueous solution was estimated by the transmittance curve [12].…”

Section: Introductionmentioning

confidence: 99%

Water sorption on a thin film of stereocontrolled poly(N-ethylacrylamide) and poly(N,N-diethylacrylamide)

Tsuchiizu

Hasegawa

Katsumoto

2013

MATEC Web of Conferences

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Abstract. The tacticity effects on the water-vapor sorption of the thin films of poly(N-ethylacrylamide) (PNEAm) and poly(N,N-diethylacrylamide) (PNdEAm) are investigated by the quartz crystal microbalance method and infrared spectroscopy. The quantity of sorbed water on the spin-coated films of isotactic-rich PNEAm is larger than that of atactic one. For PNdEAm, the syndiotactic-rich polymer film absorbs more water. The amide I or C=O stretching band of the polymers are monitored during water sorption on the spin-coated films. The result indicates that the water-sorption site is also influenced by the tacticity of the polymers. The annealing of these films wipes out the tacticity dependence of water sorption, indicating that the water-sorption sites in the spin-coated films are voids around C=O groups that are made by evaporation of solvent during spin-coating (so-called, the "solvent-imprint" effect). The isotactic-rich PNEAm is more influenced by the solvent-imprint effect than the syndiotactic-rich one, while an opposite tendency is found for PNdEAm.

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Isotactic‐specific radical polymerization of methacrylamides in the presence of Lewis acids

Cited by 68 publications

References 24 publications

Novel Initiating System for the Stereocontrolled Radical Polymerization of Acrylamides: Alkyl Bromide/Rare Earth Metal Triflate System

Novel Initiating System for the Stereocontrolled Radical Polymerization of Acrylamides: Alkyl Bromide/Rare Earth Metal Triflate System

Stereospecific living radical polymerization for simultaneous control of molecular weight and tacticity

Water sorption on a thin film of stereocontrolled poly(N-ethylacrylamide) and poly(N,N-diethylacrylamide)

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