Hochaufgelöste Kernresonanzspektren von eutaktischen Polymethylmethacrylaten

Johnsen, U.; Tessmar, K.

doi:10.1007/bf01507429

Cited by 53 publications

(11 citation statements)

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“…[1][2][3] Methacrylates can be polymerized by a variety of polymerization systems including radical, anionic, and coordination mechanisms. [1][2][3] Methacrylates can be polymerized by a variety of polymerization systems including radical, anionic, and coordination mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Syndiotactic- and heterotactic-specific radical polymerization of N-n-propylmethacrylamide complexed with alkali metal ions

et al. 2015

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We investigated the radical polymerization of N-n-propylmethacrylamide (NNPMAAm) in the presence of alkali metal bis(trifluoromethanesulfonyl)imides (MNTf 2 ), in particular LiNTf 2 . The addition of MNTf 2 led to a significant improvement in the yield and molecular weight of the resulting poly(NNPMAAm)s. Furthermore, the solvent employed influenced stereospecificity in the presence of LiNTf 2 . The stoichiometry of the NNPMAAm-Li + complex appeared to be critical for determining the stereospecificity in the NNPMAAm polymerization. The 1 : 1-complexed monomer in protic polar solvents provided syndiotacticrich polymers, whereas the 2 : 1-complexed monomer in aprotic solvents gave heterotactic-rich polymers. Stereochemical analyses revealed that m-addition by an r-ended radical was the key step in the induction of heterotactic specificity in the aprotic solvents. Spectroscopic analyses suggested that the Li + cation played a dual role in the polymerization process, with Li + stabilizing the propagating radical species and also activating the incoming monomer. Kinetic studies with the aid of electron spin resonance spectroscopy revealed that the addition of LiNTf 2 caused a significant increase in the k p value and a decrease in the k t value. The stereoregularity of poly(NNPMAAm)s was found to influence the phase transition behavior of their aqueous solutions. In a series of syndiotactic-rich polymers, the phase-transition temperature decreased gradually with increase in the rr triad content. Furthermore, heterotactic-rich poly-(NNPMAAm) exhibited high hysteresis, which increased in magnitude with increasing mr triad content. † Electronic supplementary information (ESI) available: 13 C NMR spectra of the CvO group of NNPMAAm in the presence of MNTf 2 , changes in the chemical shifts of 1 H NMR spectra of the vinylidene group of NNPMAAm in the presence of LiNTf 2 , relationship between the radical concentration and time, additional ESR spectra and relationship between the ΔT c and n r values. See

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Section: Introductionmentioning

confidence: 99%

Syndiotactic- and heterotactic-specific radical polymerization of N-n-propylmethacrylamide complexed with alkali metal ions

et al. 2015

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“…• See the literature [15,16,193,202,210,391,392,400,477,479,510,511,707] and also the section on polymerization in Chapter v.…”

Section: Polymethyl Methacrylatementioning

confidence: 99%

“…This assumption is justified, for example, in radical polymerization of methyl methacrylate. For this case there are two rate constants k i and ks for the two chain-growth reactions, and ·See literature [16,192,193,202,210,244,256,293,327,391,392,403,436,477,479,510,511,701,707,711].…”

Section: Study Of Polymerizationmentioning

confidence: 99%

The NMR of Polymers

Slonim¹,

Lyubimov²

1995

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“…[1][2][3] In particular, stereostructures have been extensively studied using NMR spectroscopies, 4 since the first reports on the triad tacticities of poly(methyl methacrylate)s, determined by 1 H NMR in 1960. [5][6][7] Recently, we reported stereospecific radical polymerizations of N-isopropylacrylamide (NIPAAm), at low temperatures, in polar solvents or in non-polar solvents, in the presence of alcohols. [8][9][10][11] The diad tacticities were easily determined from the 1 H NMR signals of the methylene groups in the main chain; the signals showed typical splitting as a result of diad stereostructures, as measured in deuterated dimethyl sulfoxide (DMSO-d 6 ) at 150 1C.…”

Section: Introductionmentioning

confidence: 99%

Application of multivariate analysis of NMR spectra of poly(N-isopropylacrylamide) to assignment of stereostructures and prediction of tacticity distribution

Hirano

Anmoto

Umezawa

et al. 2012

Polym J

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In this paper, we report multivariate analyses, such as principal component analysis and partial least-squares regression, of NMR spectra of poly(N-isopropylacrylamide)s [poly(NIPAAm)s]. Principal component analysis successfully interpreted the assignments of NMR spectra of poly(NIPAAm)s in terms of stereostructures for the methine carbons at triad levels and for the methylene protons at tetrad levels. Furthermore, triad tacticity was successfully predicted by partial least-squares regression of 1 H NMR spectra of the methine and methylene groups, although the low resolution of the signals of the methine protons confines determination of tacticities by conventional methods to the diad levels. Consequently, it is assumed that chemometric approaches are useful for assigning NMR spectra in terms of stereostructures and for predicting tacticity distributions.

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Hochaufgelöste Kernresonanzspektren von eutaktischen Polymethylmethacrylaten

Cited by 53 publications

References 0 publications

Syndiotactic- and heterotactic-specific radical polymerization of N-n-propylmethacrylamide complexed with alkali metal ions

Syndiotactic- and heterotactic-specific radical polymerization of N-n-propylmethacrylamide complexed with alkali metal ions

The NMR of Polymers

Application of multivariate analysis of NMR spectra of poly(N-isopropylacrylamide) to assignment of stereostructures and prediction of tacticity distribution

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