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

Yokotsuka, Shunsuke; Okada, Yasuo; Tojo, Yasuhisa; Sasaki, Takashi; Yamamoto, Masahide

doi:10.1295/polymj.23.95

Cited by 17 publications

(22 citation statements)

References 15 publications

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“…Here, we employed Eri = 6.5 kcal mol-1, which was obtained previously. 6 The results are shown by solid curves in Figure 8, which indicate that eq 9 can provide good fittings. From the obtained best-fit parameters, we estimated cr and O"e, assuming that b = 4.63 A.…”

Section: G=gmentioning

confidence: 80%

Primary Nucleation Rate and Radial Growth Rate of Poly(ethylene oxide) Spherulite in Viscous Solutions

Sasaki

Yamamoto

Takahashi

2000

Polym J

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The primary nucleation rate I and radial growth rate G of the isothermal spherulitic growth ofpoly-(ethylene oxide) in tripropionin solutions of 5, 10, and 30 wt% polymer concentrations were studied by direct in situ observation using a CCD camera. I was found to decrease with pre-annealing at 200°C up to ca. 200 h, while G was almost constant. These results suggest that there exist micro-residuals of a crystalline-like structure that act as dominant seeds for primary nucleation and that they become dissolved with structural relaxation during pre-annealing, resulting in the solution approaching a homogeneous state. The supercooling dependencies of I and G were independently investigated, and it was found that the fold surface free energy and activation energy of the polymer diffusion increase with decreases in the polymer content of the solution. The frictional interaction between the polymer and solvent is also discussed on the basis of the reaction rate theory ofKramers.

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Section: G=gmentioning

confidence: 80%

Primary Nucleation Rate and Radial Growth Rate of Poly(ethylene oxide) Spherulite in Viscous Solutions

Sasaki

Yamamoto

Takahashi

2000

Polym J

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“…All were prepared by anionic polymerization initiated by rc-butyllithium, and the living ends were deactivated by 9,10-bis(bromomethyl)anthracene (Figure l). 19 Here, we describe only the synthesis of the anthracene-labeled PpMS in detail. First, the initiation of anionic polymerization was started by nbutyllithium in THF at -78 °C.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, we studied the dynamic behavior of poly(alkyl methacrylate)s18 and polystyrenes. 19 For poly(alkyl methacrylate) s, the relaxation time of the local motion was studied in dilute solutions from the standpoint of molecular structure. The relaxation time became longer in the order of poly (ethyl methacrylate) ( ), poly(methyl methacrylate) (PMMA), and poly (iso-propyl methacrylate) (PiPMA).…”

Section: Introductionmentioning

confidence: 99%

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Chain Dynamics of Styrene Polymers Studied by the Fluorescence Depolarization Method

Ono¹,

Okada²,

Yokotsuka³

et al. 1994

Macromolecules

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The local motion of polystyrenes in dilute solutions was examined by the fluorescence depolarization technique. The samples, polystyrene (PS), poly(a-methylstyrene) (PaMS), and poly(pmethylstyrene) (PpMS), were labeled with the fluorescent probe anthracene in the middle of the main chain. The relaxation time of their local motion in dilute solutions was examined by fluorescence anisotropy measurement. The activation energy of the relaxation time of the polymer chain, E*, was also evaluated by the theory of Kramers' diffusion limit. There was a close correlation between the reduced relaxation time, TJ , or its activation energy and the chain expansion factor; i.e., both the reduced relaxation time and the activation energy decrease as the solvent quality becomes better. The reduced relaxation time and the activation energy depended on the local segment density of the polymer chain in the solution. The local motion for each polymer was compared in a solvent. The relaxation time and the activation energy of PaMS were larger than those of PS. This indicated that the barrier height of the local motion for a disubstituted polymer chain is higher than that for a monosubstituted one. Furthermore, the relaxation time and the activation energy of the PpMS chain were larger than those of PS.

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“…The detailed preparative technique of this sample is described elsewhere. 15 The prepared polymer was fractionated with GPC into two parts: the PS labeled at the middle of main chain, and that terminated by anthracene at _the chain end. We employed the former for fluorescence depolarization measurements.…”

Section: Preparation Of Polystyrene Samplementioning

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

Cited by 17 publications

References 15 publications

Primary Nucleation Rate and Radial Growth Rate of Poly(ethylene oxide) Spherulite in Viscous Solutions

Primary Nucleation Rate and Radial Growth Rate of Poly(ethylene oxide) Spherulite in Viscous Solutions

Chain Dynamics of Styrene Polymers Studied by the Fluorescence Depolarization Method

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

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