Conformational exchange near the glass transition: two-dimensional carbon-13 NMR study of atactic polypropylene

Zemke, K.; Chmelka, Bradley F.; Schmidt‐Rohr, Klaus; Spiess, Hans Wolfgang

doi:10.1021/ma00026a017

Cited by 54 publications

(48 citation statements)

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“…The cross-peaks prove the existence of translational diffusion between the crystalline and amorphous regions well below the melting temperature. Similar experiments were applied to study conformational transitions [109]. Fig.…”

Section: D-and 3d-exchange Nmr Experimentsmentioning

confidence: 97%

“…From these measurements the mean correlation times (decay times) as a function of the temperature can be obtained and the activation energy of the ionic motion determined. Other STE studies on ionic conductors have been carried out using 109 Ag NMR (spin 1 ⁄ 2 system). In this case two-time and three-time correlation functions were obtained, and it was concluded that the non-exponentiality observed in the correlation function is due to a correlation time distribution, i.e.…”

Section: D Exchange Nmr Experimentsmentioning

confidence: 99%

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Molecular dynamics in solid polymers

deAzevedo¹,

Bonagamba²,

Reichert

2005

Progress in Nuclear Magnetic Resonance Spectroscopy

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Section: D-and 3d-exchange Nmr Experimentsmentioning

confidence: 97%

Section: D Exchange Nmr Experimentsmentioning

confidence: 99%

Molecular dynamics in solid polymers

deAzevedo¹,

Bonagamba²,

Reichert

2005

Progress in Nuclear Magnetic Resonance Spectroscopy

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“…12 However, afterwards it has been shown for, e.g., polypropylene that a significant portion of rotational processes around T g can be identified as conformational transitions of the main chain, which involve large angle jumps. 13,14 The relevance of large angle jumps for the rotational dynamics around T g was also corroborated from molecular dynamics simulations. 15 Motivated by these additional findings it has been shown that a fit of equal quality for the 2D spectra of PS can be obtained under the assumption that apart from small angle fluctuations also large angle jumps are important for the reorientation process.…”

Section: Introductionmentioning

confidence: 64%

“…The bimodal distribution of librational rates could result from possible different dynamics perpendicular and parallel to the polymer chain. However, due to the observation of conformational transitions 13,14 and the results of the full 3D experiment 16 we rather favor the scenario of small angle fluctuations and conformational transitions.…”

Section: Dico Spectra Of Polystyrenementioning

confidence: 72%

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Geometry and time scale of the complex rotational dynamics of amorphous polymers at the glass transition by multidimensional nuclear magnetic resonance

Heuer

Leisen

Kuebler

et al. 1996

The Journal of Chemical Physics

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We present a new multidimensional NMR exchange experiment, three dimensional difference correlated exchange spectroscopy ͑DICO͒, which allows one to extract detailed information about the time scale as well as the geometry of rotational processes simultaneously. In contrast to experiments presently available the geometric information specified by a dynamic order parameter is independent of a specific model. Among others full isotropisation can be directly seen from the spectrum via a symmetry criterion. We apply this method to study the chain motion of polystyrene slightly above the glass transition. The DICO spectra prove that a typical chain segment performs small angle fluctuations as well as large angle jumps which can neither be described as random jumps nor tetrahedral jumps. A typical jump angle can be estimated to be of the order of 30°Ϫ40°.

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Dynamics in the crystalline polymorphic forms I and II and form III of isotactic poly-1-butene

Maring

Wilhelm

Spieß

et al. 2000

J. Polym. Sci. B Polym. Phys.

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Following an earlier study of the 1H relaxation and NMR line shapes, we have carried out selective one‐dimensional and two‐dimensional 13C solid‐state NMR studies that yield to detailed interpretation of the dynamics in form I, II, and III polymorphs of isotactic poly‐1‐butene. A specific defect diffusion along the side group is proposed to account for the temperature dependence of the 13C spectra in form I. The backbone of the helix in forms II and III is shown to undergo large angle motions above the glass‐transition temperature. High‐resolution solid‐state 13C two‐dimensional exchange NMR under magic‐angle spinning with cross‐polarization techniques demonstrates the existence of slow rotational jumps of the helices in form III with typical jump rates of about 10 s−1. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2611–2624, 2000

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Conformational exchange near the glass transition: two-dimensional carbon-13 NMR study of atactic polypropylene

Cited by 54 publications

References 1 publication

Molecular dynamics in solid polymers

Molecular dynamics in solid polymers

Geometry and time scale of the complex rotational dynamics of amorphous polymers at the glass transition by multidimensional nuclear magnetic resonance

Dynamics in the crystalline polymorphic forms I and II and form III of isotactic poly-1-butene

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