Carbon-13 NMR investigation of local dynamics in bulk polymers at temperatures well above the glass-transition temperature. 4. Polyisobutylene

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

doi:10.1021/ma00196a013

Cited by 60 publications

(77 citation statements)

References 1 publication

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“…͑4.2͒, which in the temperature range of study amounts to 0.60 eV. The experimental activation energy is in the range of that for the NMR correlation time associated with correlated conformational jumps in bulk PIB by Dejean de la Batie et al 24 ͑0.46 eV͒ and one could tentatively relate 0 to the mechanism underlying this process. However, although a similar temperature dependence is found for 0 and the NMR correlation time, the obtained absolute values for 0 are significantly slower.…”

Section: Internal Viscosity Approachmentioning

confidence: 62%

From Rouse dynamics to local relaxation: A neutron spin echo study on polyisobutylene melts

Richter

Monkenbusch

Allgeier

et al. 1999

The Journal of Chemical Physics

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We investigated the single chain motions of monodisperse polyisobutylene chains in the melt by neutron spin echo spectroscopy. Thereby a wide range in momentum space over a large dynamic range was covered. Motional processes from the center of mass diffusion, the Rouse dynamics to the more local relaxation processes which limit the validity of the standard Rouse model, were elucidated. The observed dynamic structure factors were analyzed in terms of relevant theoretical approaches addressing the limiting factors of the Rouse model. We found that other than claimed in the literature effects of local chain stiffness-they were treated in terms of the all rotational states model and a bending force model-cannot account for the experimental observations. It appears that additional damping effects related to an internal viscosity of the chain have to be involved, in order to explain the experimental results.

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Section: Internal Viscosity Approachmentioning

confidence: 62%

From Rouse dynamics to local relaxation: A neutron spin echo study on polyisobutylene melts

Richter

Monkenbusch

Allgeier

et al. 1999

The Journal of Chemical Physics

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“…These experiments measure the activation energy of the spin-lattice relaxation time T 1 which is related to the sum of the activation energy of the local process E loc and that of the viscosity E η : E T1 ) E loc + E η . From such an evaluation of T 1 experiments Dejean de la Batie et al 8 found E loc ) 5 kcal/mol for PIB in chloroform, while Jones et al 9 and Inoue et al 10 This data array fits the upper range of the rotational barriers of the hydrocarbons which are found typically between 3 e E e 3.5 kcal/mol. The value of 3.1 kcal/ mol for the activation energy of τ 0 resulting from the intrachain viscosity analysis of our PIB/toluene data is …”

Section: Analysis and Discussionmentioning

confidence: 75%

Origin of Internal Viscosity Effects in Flexible Polymers: A Comparative Neutron Spin-Echo and Light Scattering Study on Poly(dimethylsiloxane) and Polyisobutylene

et al. 2001

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We present a comparative neutron spin-echo and dynamic light scattering study of the chain dynamics of the dynamically very flexible poly(dimethylsiloxane) (PDMS) with the orientationally hindered polyisobutylene (PIB). Both polymers exhibit the same static rigidity. In the melt PDMS follows the Rouse dynamics up to momentum transfers of Q ) 0.4 Å -1 , while PIB displays a strong influence of local dynamics already above Q ) 0.15 Å -1 . In dilute solution the dynamic structure factors and the diffusion coefficients of both polymers were studied over a wide temperature and Q range. A comparative evaluation of the PIB intrachain dynamics on the basis of PDMS results, which are taken to reflect as in the melt "ideal" relaxations, shows that intrachain viscosity effects are the leading mechanism displayed by the Rouse and Zimm models. The characteristic relaxation time of the intrachain viscosity τ 0 agrees well with the rotational barriers in PIB, corroborating the underlying physical idea of a delayed redistribution of conformational states to be at the origin of internal viscosity effects.

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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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Carbon-13 NMR investigation of local dynamics in bulk polymers at temperatures well above the glass-transition temperature. 4. Polyisobutylene

Cited by 60 publications

References 1 publication

From Rouse dynamics to local relaxation: A neutron spin echo study on polyisobutylene melts

From Rouse dynamics to local relaxation: A neutron spin echo study on polyisobutylene melts

Origin of Internal Viscosity Effects in Flexible Polymers: A Comparative Neutron Spin-Echo and Light Scattering Study on Poly(dimethylsiloxane) and Polyisobutylene

Local dynamics of isotactic and syndiotactic polypropylene in solution

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