Carbon-13 NMR investigation of local dynamics in bulk polymers at temperatures well above the glass transition temperature. 2. Poly(propylene oxide) and linear and cross-linked poly(ethylene oxides)

Batie, R. Dejean de la; Lauprêtre, F.; Monnerie, L.

doi:10.1021/ma00185a029

Cited by 55 publications

(44 citation statements)

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“…This last observation implies that the local motions of the carbons near the cross-links are fast enough to allow the observation of these carbons under the conventional solution-type NMR conditions used here. An opposite result was reported by Dejean et al 3 for urethane crosslinked PEO networks in the same temperature range, for Table 11. At 25 "C, the line width is practically independent of the length of the PEO Segments.…”

Section: Resultscontrasting

confidence: 59%

Influence of the chemical nature of cross-links on the local dynamics of bulk poly(ethylene oxide) networks as studied by carbon-13 NMR at temperatures well above the glass-transition temperature

Lestel¹,

Guégan²,

Boileau³

et al. 1992

Macromolecules

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Carbon-13 spin-lattice relaxation time measurements have been performed on cyclosiloxane cross-linked poly(ethy1ene oxide)s (PEO) in bulk at temperatures well above the glass-transition temperature. The introduction of cyclosiloxane cross-links does not induce a strong modification of the local dynamics of PEO segments, in contrast to results observed in urethane cross-linked PEOs. Moreover, in these networks, the local chain dynamics are satisfactorily described by considering a damped bond orientation diffusion process and a fast libration of limited extent of the internuclear CH vectors about their rest position. The amplitude of the libration, which is expected to reflect the steric hindrance at the considered site, does not depend on the carbon considered and the chemical nature and density of cross-links. IntroductionResearch on ionically conducting polyether-based networks containing alkali-metal salts has been developed during the last decade, because improved mechanical properties and higher conductivity values due to a lower crystallinity of the materials were expected, compared to the behavior of linear polyethers. Well-defined poly-(ethylene oxide) (PEO) networks with urethane or cyclosiloxane cross-links have been prepared, and the conductivity of these products filled with lithium salts has been studied.lI2 Flexible cyclosiloxane cross-links lead to membranes which have conductivity values higher than those of the more rigid and polar aromatic urethane crosslinks. Moreover, the ionization process was shown to depend on the chemical nature of the cross-links.2 As charge transport is related to the segmental chain motions, a study of the influence of the cross-links on the mobility of PEO segments was undertaken.Among the techniques that permit investigation of local chain dynamics, analysis of 13C spin-lattice relaxation times 2' 1 leads to a detailed description of local motions. Moreover, in bulk polymers at temperatures well above the glass-transition temperature, Tg, the carbon-proton dipolar interaction and the chemical shift anisotropy are averaged to a large extent by fast local motions and contribute only to a weak residual line broadening. Therefore, high-resolution l3C NMR spectra can be obtained on these materials by using the conventional spectrometers for solution investigations.This technique has been used t o determine carbon-13 spin-lattice relaxation times TI in cyclosiloxane crosslinked PEO networks at temperatures well above the glasstransition temperature. The results, which are compared

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Section: Resultscontrasting

confidence: 59%

Influence of the chemical nature of cross-links on the local dynamics of bulk poly(ethylene oxide) networks as studied by carbon-13 NMR at temperatures well above the glass-transition temperature

Lestel¹,

Guégan²,

Boileau³

et al. 1992

Macromolecules

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“…The fit was achieved by treating simultaneously the 25 and 50 MHz T 1 data assuming for the motional model a time scale separation between the fast librations and the segmental motions, as was systematically observed in previously studied polymer chains. 9,[15][16][17] The parameters 2 / 1 and a are kept constant over the whole temperature range while 1 is assumed to vary according to Arrhenius' law 1 ϭA exp(E a /k B T). For a given microstructure, common values of the activation energies E a and prefactors A are adopted for both methylene and methine carbons.…”

Section: Resultsmentioning

confidence: 99%

“…The detailed analysis of relaxation data determined in a number of polymer systems, 9,[15][16][17][18][19][20][21][22] either in solution or in bulk at temperatures well above the glass transition temperature, has shown that the local motions observed by 13 C spinlattice relaxation can be satisfyingly described in terms of damped diffusion of bond orientation along the chain sequence, which represents the segmental motions, and independent fast bond librations. 9 The corresponding orientation autocorrelation function is written as…”

Section: -mentioning

confidence: 99%

Local dynamics of isotactic and syndiotactic polypropylene in solution

Destrée

Lauprêtre

Lyulin

et al. 2000

The Journal of Chemical Physics

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The local dynamics of polypropylene ͑PP͒ in solution is studied by 13 C NMR relaxation and by molecular dynamics ͑MD͒ simulation via the orientational autocorrelation function ͑OACF͒ of C-H bonds. The interpretation protocol of this function proposed by Dejean de la Bâtie, Lauprêtre and Monnerie ͑DLM͒ ͓R. Dejean de la Bâtie, F. Lauprêtre, and L. Monnerie, Macromolecules 21, 2045͑1988͔͒ is applied and tested on new NMR measurements of the various microstructures of polypropylene. This interpretation scheme of the OACF is supported by a detailed study employing simulated PP trajectories in an atomistic heat bath. MD simulations indicate that, quite generally, the correlation time for segmental motions, 1 , extracted from the DLM motional model is closely linked with the mean time between conformational jumps. Both experiments and simulations suggest a slightly higher mobility of meso sequences by comparison with racemic sequences. Our analysis of the microscopic aspects of the segmental dynamics and its manifestation in motional models allows us to trace the microscopic origin of the larger mobility of meso sequences.

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“…However, PPO, because of its noncrystallizability and availability in a wide molecular weight range, is acceptable as a model object for close examination of relaxation properties of flexible chain polymers. Its relaxation characteristics, basically those of the corresponding low molecular weight OH-ended analogue, so-called poly(propylene glycol) (PPG), have been intensively studied using dielectric, [1][2][3][4][5][6] optical, 7-10 nuclear magnetic resonance (NMR), [11][12][13] quasi-elastic neutron scattering, 14,15 and ultrasonic, [16][17][18][19][20][21] techniques, as well as various methods for probing viscoelastic properties. [22][23][24] In contrast to PPO, PEO and PTMO are possible to crystallize and they can be closely investigated only in a temperature range above the melting point.…”

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Acoustic Relaxation of Liquid Poly(tetramethylene oxide) with Hydroxyl and Acyl Terminal Groups

Шилов

Sperkach

et al. 2002

Polym J

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ABSTRACT:Isotherms of sound absorption and velocity vs. frequency were measured for poly(tetramethylene oxide)-2000 ended by CH 3 and OH groups. The measurements were performed at 5-2500 MHz and at different temperatures at 313-353 K. The results are presented and analysed using different formats to examine the frequency dependence of the attenuation α(is sound attenuation at frequency f , α exc is excess sound attenuation at frequency f , and λ is the sound wavelength) as well as frequency dependence of real (M ) and imaginary (M ) parts of the mechanic modulus. Two dispersion regions are present on all sound absorption isotherms. Arrhenius curves of the relaxation time are fitted and analysed using Vogel-Tamann-Fulcher and Kohlrausch-WilliamsWatts functions. Relaxation time in the first dispersion region, as well as relaxation strength, are less affected by the terminal groups of PTMO than in the second dispersion region. Alternation of the different end-capping groups has greater influence on the relaxation strength values of the second dispersion region characteristic of the local segmental motions of the polymers.KEY WORDS Poly(tetramethylene oxide) / Ultrasonic Spectra / Relaxation Time /The simplest aliphatic polyethers such as poly(methylene oxide) (PMO), poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), and poly(tetramethylene oxide) (PTMO) are well known polymers and widely used for industry and fundamental scientific interest. However, PPO, because of its noncrystallizability and availability in a wide molecular weight range, is acceptable as a model object for close examination of relaxation properties of flexible chain polymers. Its relaxation characteristics, basically those of the corresponding low molecular weight OH-ended analogue, so-called poly(propylene glycol) (PPG), have been intensively studied using dielectric, 1-6 optical, 7-10 nuclear magnetic resonance (NMR), 11-13 quasi-elastic neutron scattering, 14, 15 and ultrasonic, 16-21 techniques, as well as various methods for probing viscoelastic properties. [22][23][24] In contrast to PPO, PEO and PTMO are possible to crystallize and they can be closely investigated only in a temperature range above the melting point. Consequently, dynamics of such polyethers in their liquid/amorphous state is studied to a far lesser degree than that of PPG. There are a vast number of papers devoted to investigation of the relaxation features of OH-group end-capped low molecular weight PEO, poly(ethylene glycol) (PEG). The corresponding results are obtained using dielectric, [25][26][27]28 Brillouin scattering, 29 and ultrasonic, 30-32 techniques.PPGs and PEGs are characterised for the most part by a presence of two room temperature dispersion regions, corresponding to the relaxation times of 10 −8 and 10 −10 s. Those of PEG and PPG are rather close to each other at the same temperatures.It follows from the one paper 33 on relaxation behaviour of PTMO in a liquid state that room temperature quasielastic neutron spectra correspond to a relaxation time ...

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Carbon-13 NMR investigation of local dynamics in bulk polymers at temperatures well above the glass transition temperature. 2. Poly(propylene oxide) and linear and cross-linked poly(ethylene oxides)

Cited by 55 publications

References 1 publication

Influence of the chemical nature of cross-links on the local dynamics of bulk poly(ethylene oxide) networks as studied by carbon-13 NMR at temperatures well above the glass-transition temperature

Influence of the chemical nature of cross-links on the local dynamics of bulk poly(ethylene oxide) networks as studied by carbon-13 NMR at temperatures well above the glass-transition temperature

Local dynamics of isotactic and syndiotactic polypropylene in solution

Acoustic Relaxation of Liquid Poly(tetramethylene oxide) with Hydroxyl and Acyl Terminal Groups

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