Local dynamics of polyisoprene in toluene

Gisser, Daniel J.; Głowinkowski, S.; Ediger, M. D.

doi:10.1021/ma00015a007

Cited by 79 publications

(66 citation statements)

References 13 publications

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“…Here the constant K is taken to be 2.29ϫ10 9 s Ϫ2 , 21 and n is the number of bonded protons. Outside the extreme narrowing regime, T 1 DD and NOE DD depend upon the spectral density function as follows:…”

Section: ͑7͒mentioning

confidence: 99%

Segmental dynamics in a blend of alkanes: Nuclear magnetic resonance experiments and molecular dynamics simulation

Budzien

Raphael

Ediger

et al. 2002

The Journal of Chemical Physics

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The segmental dynamics of a model miscible blend, C 24 H 50 and C 6 D 14 , were investigated as a function of temperature and composition. The segmental dynamics of the C 24 H 50 component were measured with 13 C nuclear magnetic resonance T 1 and nuclear Overhauser effect measurements, while 2 H T 1 measurements were utilized for the C 6 D 14 component. Use of low molecular weight alkanes provides a monodisperse system in both components and allows differentiation of dynamics near the chain ends. From these measurements, correlation times can be calculated for the C-H and C-D bond reorientation as a function of component, position along the chain backbone, temperature, and composition. At 337 K, the segmental dynamics of both molecules change by a factor of 2 to 4 across the composition range, with the central C-H vectors of tetracosane showing a stronger composition dependence than other C-H or C-D vectors. Molecular simulations in the canonical and isobaric-isothermal ensembles were conducted with a united-atom force field that is known to reproduce the thermodynamic properties of pure alkanes and their mixtures with good accuracy. With a minor change to the torsion parameters, the correlation times for pure tetracosane are in good agreement with experiment. For pure hexane and its mixtures with tetracosane, the simulated dynamics are faster than experiment.

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Section: ͑7͒mentioning

confidence: 99%

Segmental dynamics in a blend of alkanes: Nuclear magnetic resonance experiments and molecular dynamics simulation

Budzien

Raphael

Ediger

et al. 2002

The Journal of Chemical Physics

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“…In our calculations, we take K to be 2.29ϫ10 9 s Ϫ2 . 13 Of experimental interest is also the nuclear Overhauser effect ͑NOE͒.…”

Section: Intramolecular Dynamicsmentioning

confidence: 99%

Molecular dynamics of linear and branched alkanes: Simulations and nuclear magnetic resonance results

Mondello

Grest

Garcia

et al. 1996

The Journal of Chemical Physics

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Articles you may be interested inThe effects of pressure and temperature on molecular dynamics during linearchain polymerization by dielectric measurements A constrained maximum entropy method for the interpretation of experimental data: Application to the derivation of single particle orientationconformation distributions from the partially averaged nuclear spin dipolar couplings of nalkanes dissolved in a liquid crystalline solvent NonGaussian behavior and the dynamical complexity of particle motion in a dense twodimensional liquidWe have extended two previously introduced models of n-alkanes to numerically investigate the liquid-state dynamics of branched alkanes. We compare our results with new experimental measurements of diffusion and 13 C-NMR T 1 relaxation. Significant systematic and quantitative agreement is found between simulated and experimental values. We demonstrate the role of branching in controlling the temperature dependence of diffusion and point out the effect of global single-chain relaxation processes on the local intramolecular dynamics probed by the 13 C-NMR experiment.

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“…Each 1 ns of the simulation trajectory required about 1 h of CPU time on an IBM 3090 with a vector processor. A typical simulation length was [10][11][12][13][14][15][16][17][18][19][20] ns.…”

Section: Simulation Descriptionmentioning

confidence: 99%

Brownian dynamics simulations of local motions in polyisoprene

Adolf¹,

Ediger²

1991

Macromolecules

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Brownian dynamics computer simulations have been performed on polyisoprene chains containing 67 repeat units. The simulated trajectories were used to generate three orientational autocorrelation functions analogous to those sensed by l3C NMR 2' 1 experiments. Agreement between the simulation and dilute-solution NMR experiments is encouraging. Differences in the dynamics of various C-H vectors in the polymer backbone are quantitatively reproduced by the simulation. The simulations indicate the presence of substantial librational motions on a time scale of a few picoseconds. Correlated pairsof transitions occur infrequently. The role of cooperativity in conformational transitions is examined, and a new method of examining cooperativity is presented. For polyisoprene, distortions in atomic positions accompanying a conformational transition are localized to about one repeat unit.

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Local dynamics of polyisoprene in toluene

Cited by 79 publications

References 13 publications

Segmental dynamics in a blend of alkanes: Nuclear magnetic resonance experiments and molecular dynamics simulation

Segmental dynamics in a blend of alkanes: Nuclear magnetic resonance experiments and molecular dynamics simulation

Molecular dynamics of linear and branched alkanes: Simulations and nuclear magnetic resonance results

Brownian dynamics simulations of local motions in polyisoprene

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