Local segmental dynamics of polyisoprene in dilute solution: solvent and molecular weight effects

Waldow, Dean A.; Johnson, Bruce M.; Hyde, Patrick D.; Ediger, M. D.; Kitano, Toshiaki; Ito, Koichi

doi:10.1021/ma00193a056

Cited by 27 publications

(25 citation statements)

References 7 publications

(13 reference statements)

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“…Our suggestion in this study does not intend to deny the concept of the segment density proposed by Waldow et a/. 21 In our previous study, it was shown that PI is dynamically more flexible than PS. 1 7 Therefore, the excluded-volume effect for PI may be more effective than that for PS and the local motion is mainly determined by the segment density in the high molecular weight regwn.…”

Section: Relaxation Timementioning

confidence: 68%

“…Waldow et al showed that the relaxation time for the local motion of the chain center of PI does not change with molecular weight in a good solvent, whereas the relaxation time increases with molecular weight in a e solvent. 21 They explained these observations by the local segment concentration about the labeled segment. That is, the molecular weight independence of the relaxation time in a good solvent is due to the excluded-volume effect, which tends to keep segments which are far apart along the chain contour far separated in space.…”

Section: Relaxation Timementioning

confidence: 97%

“…have examined the molecular weight effect on polyisoprene (PI) chain dynamics and concluded that the chain dynamics is governed by the segment density in the vicinity of the fluorescent probe labeled in the middle of the main chain. 21 Previously, we reported the molecular weight effect for poly( methyl methacrylate) samples and explained the behavior of the local chain dynamics by the segment density as well. 19 We also have reported the local chain dynamics of poly(oxyethylene) (POE) in good solvents and discussed the molecular weight effect.…”

mentioning

confidence: 92%

“…1 -21 For the local motion, which is fairly a fundamental process in chain dynamics, many experimental methods have been utilized, e.g., NMR, 5 -7 ESR, 8 dielectric relaxation, 9 -11 dynamic light scattering, 12 • 13 neutron scattering, 14 and fluorescence depolarization. [15][16][17][18][19][20][21] The fluorescence depolarization method provides direct information about the local motion of polymer chains through a fluorescent probe that is covalently bonded to the polymer main chain. By using this method, we have examined the influence of molecular structure/ 6 · 19 stereoregularity, 17 and quality of solvent16·18 on the chain dynamics of a variety of polymers.…”

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confidence: 99%

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Molecular Weight Effect on Local Motion of Polystyrene Studied by the Fluorescence Depolarization Method

Horinaka

Aoki

Ito

et al. 1999

Polym J

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ABSTRACT:The molecular weight effect on the local motion of polystyrene (PS) was examined in dilute solutions by the fluorescence depolarization method. Four PS samples with the fluorescent probe, anthryl group, in the middle of the main chain were synthesized by the living anionic polymerization. The molecular weight of samples varied from ca. 6.4 x 10 3 to 9.2 x 10 4 Solvents were benzene, a good solvent and ethyl acetate, a poor solvent. In both solvents, the relaxation time increased with the molecular weight up to MW = 10 4 at which it reached an asymptotic value. The activation energies were also estimated from the temperature dependence of the relaxation time, and its molecular weight dependence appeared to be similar to that of the relaxation time. It was suggested that the relaxation time of the local motion is determined by the potential for the conformational transition of main chain bonds, rather than by the segment density. Finally, the molecular weight effect on the relaxation time for PS was compared with that for poly(oxyethylene) (POE The flexible polymer chain in dilute solution has various motional scales with regard to time and space resulting from its high degree of intramolecular freedom. Because this chain dynamics governs a variety of properties of polymers, extensive experimental and theoretical efforts have been made to understand the polymer chain dynamics. 1 -21 For the local motion, which is fairly a fundamental process in chain dynamics, many experimental methods have been utilized, e.g., NMR, 5 -7 ESR, 8 dielectric relaxation, 9 -11 dynamic light scattering, 12 • 13 neutron scattering, 14 and fluorescence depolarization.15-21 The fluorescence depolarization method provides direct information about the local motion of polymer chains through a fluorescent probe that is covalently bonded to the polymer main chain. By using this method, we have examined the influence of molecular structure/ 6 · 19 stereoregularity, 17 and quality of solvent16·18 on the chain dynamics of a variety of polymers.The local chain dynamics in dilute solution is influenced by the molecular weight of the polymer in addition to those factors mentioned above. Concerning the fluorescence depolarization study, Waldow et a!. have examined the molecular weight effect on polyisoprene (PI) chain dynamics and concluded that the chain dynamics is governed by the segment density in the vicinity of the fluorescent probe labeled in the middle of the main chain. 21 Previously, we reported the molecular weight effect for poly( methyl methacrylate) samples and explained the behavior of the local chain dynamics by the segment density as well. 19 We also have reported the local chain dynamics of poly(oxyethylene) (POE) in good solvents and discussed the molecular weight effect. 20The static and dynamic properties of polystyrene (PS), a common polymer, have been widely studied. 2 · 6 -9 • 16 · 17 We have reported the effects of the solvent quality on the local dynamics of PS 17 and discussed the difference t To whom correspondenc...

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Section: Relaxation Timementioning

confidence: 68%

Section: Relaxation Timementioning

confidence: 97%

mentioning

confidence: 92%

mentioning

confidence: 99%

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Molecular Weight Effect on Local Motion of Polystyrene Studied by the Fluorescence Depolarization Method

Horinaka

Aoki

Ito

et al. 1999

Polym J

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“…7 In addition, the temperature dependence of the chain expansion is stronger in a poor solvent than in a good solvent, and this may contribute to the stronger temperature dependence of T m in poor solvent than in good solvent. 14 Comparison of the results shown in Tables V and VI revealed no significant differences in Ea in the case of butyl acetate and cyclohexane. Therefore, the usual treatment based on eq 6 is generally adequate for the local motions in these two solvents, i.e., the local relaxation time T m can be described by eq 6 (high friction limit).…”

Section: Resultsmentioning

confidence: 85%

Activation Energy of Local Polymer Motions Estimated from the Fluorescence Depolarization Measurements

Yokotsuka

Okada

Tojo

et al. 1991

Polym J

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ABSTRACT:Activation energies of local conformational transItIOns in polymers were investigated by the fluorescence depolarization method. The mean relaxation time related to the local conformational transitions was measured for dilute solutions of the anthracene-labeled polystyrene (PS), and anthracene-labeled polY(IX-methylstyrene) (PIXMS) in various solvents. The obtained data were successfully analyzed by use of the generalized formula of Helfand based on the reaction rate theory of Kramers. The results showed that the activation energy is larger in poor solvents than in good solvents which reflects the chain expansion effect. It is clear that the apparent activation energy is influenced by two types of polymer-solvent interactions, i.e., the frictional interaction (short-range interaction) and the chain expansion effect (long range interaction), and that the former can also be evaluated roughly by the present analysis.

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Local Chain Mobility of Gellan in Aqueous Systems Studied by Fluorescence Depolarization

Horinaka

Kani

Honda

et al. 2004

Macromolecular Bioscience

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The local chain mobility of a gellan, an electrolyte polysaccharide, in aqueous systems was examined with respect to the effect of the temperature, the concentration of gellan (c(G)), and the concentration of added salt (c(S)). The relaxation time of local motion was estimated for fluorescein isothiocyanate (FITC)-labeled-gellan by the fluorescence depolarization technique, and the chain mobility was discussed. The relaxation time increased with decreasing temperature, in particular when accompanying the coil-helix transition due to the great difference in chain mobility between the coil and the helical conformations. The effect of c(G) was observed for gellan solutions even below the critical concentration of chain entanglement (2 wt.-%) for well-expanded nonelectrolyte polymers with size similar to that of the gellan. This suggests that the actual excluded volume of gellan is larger than that of nonelectrolyte polymers due to the electrostatic repulsion between segments. The relaxation time for 0.2 wt.-% systems of gellan in coil conformation is independent of c(S), whereas a c(S) dependence of the relaxation time is clearly observed for 0.5 wt.-% systems. The degree of expansion of the gellan chain is independent of the shielding effect of cations on the electrostatic repulsion between gellan segments due to the stiffness of gellan chain. On the other hand, the c(G) as well as the c(S) dependence of the chain mobility is clearly observed for gellan in the helical conformation, examined over the concentration range, probably due to the partial aggregation of helices induced by the attractive interaction between gellan segments.

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Local segmental dynamics of polyisoprene in dilute solution: solvent and molecular weight effects

Cited by 27 publications

References 7 publications

Molecular Weight Effect on Local Motion of Polystyrene Studied by the Fluorescence Depolarization Method

Molecular Weight Effect on Local Motion of Polystyrene Studied by the Fluorescence Depolarization Method

Activation Energy of Local Polymer Motions Estimated from the Fluorescence Depolarization Measurements

Local Chain Mobility of Gellan in Aqueous Systems Studied by Fluorescence Depolarization

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