Viscosity dependence of the local segmental dynamics of anthracene-labeled polyisoprene in dilute solution

Adolf, David B.; Ediger, M. D.; Kitano, Toshiaki; Ito, Koichi

doi:10.1021/ma00028a055

Cited by 55 publications

(93 citation statements)

References 3 publications

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“…12, 1994 evaluated by the theory of Kramers' diffusion limit in the solvents below 2 cP. Adolf et al 25 reported the same finding for the solvents of viscosity below 2cP (at 46°C). In our previous paper, 29 for the dynamics of PS in a highly viscous solvent, the slope of ln(Tm) against ln(17) was less than unity.…”

Section: Resultsmentioning

confidence: 73%

“…Adolf et al 25 reported for PT solutions that in high viscosity solvents, the theory of Kramers' diffusion limit cannot be used to evaluate the activation energy, i.e., the friction between polymer segments and solvent molecules is not proportional to solvent viscosity. They plotted ln( Tm) against ln( 1J ), and obtained a slope of 0.41.…”

Section: Resultsmentioning

confidence: 99%

“…Now, we discuss the effect ofstereoregularity on the local motion of polymer chains. Adolf et al 25 examined the local motion of PI with a cis-1,4 content of 54 % by the fluorescence depolarization method. They observed the activation energies in solvents in a wide viscosity range, 0.4--35 cP at 45°C.…”

Section: The Activation Energy For Cis-pimentioning

confidence: 99%

“…Previously, Adolf et al 25 examined the local motion of cis-PI by the same method of fluorescence depolarization, but the cis content of their PI sample was small, 54%. Here, we synthesized anthracene-labeled cis-PI with a higher cis content, 76%.…”

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confidence: 99%

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Local Chain Dynamics of Poly(cis-1,4-isoprene) in Dilute Solutions Studied by the Fluorescence Depolarization Method

Ono

Ueda

Yamamoto

1994

Polym J

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ABSTRACT:Local segmental motions of poly(cis-1,4-isoprene) (cis-PI) labeled with anthracene were examined by the method of fluorescence depolarization using 1,4-dioxane, n-dodecane, cyclohexane, benzene, ethylbenzene, and a-xylene as the solvents with a viscosity of less than 2 cP. The anisotropy ratio was measured in these dilute solutions, and the mean relaxation time, Tm, for the chain local motion was obtained. The activation energy, E*, was obtained by using the theory of Kramers' diffus10n limit. The reduced relaxation time, Tm/I/, for cis-PI was much shorter than that for polystyrene and was independent of the local segment density differing from that of polystyrene. The dependence of activation energy, E*, on the solvent was very weak, compared to that of polystyrene. These findings could be interpreted in terms of the dynamic flexibility of the polymer chain.

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Section: Resultsmentioning

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Section: The Activation Energy For Cis-pimentioning

confidence: 99%

mentioning

confidence: 99%

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Local Chain Dynamics of Poly(cis-1,4-isoprene) in Dilute Solutions Studied by the Fluorescence Depolarization Method

Ono

Ueda

Yamamoto

1994

Polym J

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“…A similar anomaly of polymer chain dynamics in high viscosity solvents has also been reported by other workers. 33 -36 For example, Ediger et al 33 reported that the theory of Kramers' diffusion limit gives a negative value for an activation energy of polyisoprene in dioctylphthalate.…”

Section: )mentioning

confidence: 99%

Chain Dynamics of Polystyrene in High Viscosity Solvents Studied by the Fluorescence Depolarization Method

Ono

Okada

Yokotsuka

et al. 1994

Polym J

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ABSTRACT:Polystyrene (PS) labeled with anthracene in the middle of the main chain was prepared, and the relaxation time of their local motion in the solvents with various viscosities was examined by the fluorescence depolarization technique. We measured the relaxation time of emission anisotropy, Tm, in four kinds of mixed solvents of diethylphthalate (DEP) and cyclohexanone (CHO). These are good solvents for PS and have different viscosities. With the addition of DEP to cyclohexanone, i.e., with the increase in solvent viscosity, the activation energy of Tm, E*, obtained by using the reaction rate theory of Kramers in the high friction (diffusion limit) changed from a positive value to a negative value. The value of E* was also negative in the case of tripropionin, which is a poor solvent for PS and has a high viscosity. Therefore, we conclude that the negative E* does not depend on the quality of the solvent, i.e., whether the solvents are good or poor, but on the viscosity of the solvent. Then, we evaluated E* on the basis of Grote-Hynes' equation and of the Robinson's equation. The analysis by the Robinson's equation gave positive values of E*. The anomaly of the activation energies of the local motions may be explained by the movement of the polymer chains in an ordered solvent of strong intermolecular interaction.

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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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Viscosity dependence of the local segmental dynamics of anthracene-labeled polyisoprene in dilute solution

Cited by 55 publications

References 3 publications

Local Chain Dynamics of Poly(cis-1,4-isoprene) in Dilute Solutions Studied by the Fluorescence Depolarization Method

Local Chain Dynamics of Poly(cis-1,4-isoprene) in Dilute Solutions Studied by the Fluorescence Depolarization Method

Chain Dynamics of Polystyrene in High Viscosity Solvents Studied by the Fluorescence Depolarization Method

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

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