Local Chain Motion of Isotactic and Syndiotactic Poly(methyl methacrylate)s Studied by the Fluorescence Depolarization Method

Ono, Kentaro; Sasaki, Tsuyoshi; Yamamoto, Masahide; Yamasaki, Yumi; Ute, Koichi; Hatäda, Koichi

doi:10.1021/ma00118a033

Cited by 16 publications

(32 citation statements)

References 14 publications

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“…In the absence of EET explicit solutions to the fluorescence depolarization response of a single chromophore subjected to correlated, local conformational changes have been given by Szabo 12 for both free and restricted Langevin motion. Similar targets have been realized by Viovy et al, 13 Sasaki et al 14 or Ono et al 15 on the basis of orientational autocorrelation functions of chromophores, calculated from different models of conformational motion. In the high-density regime of sites, Fredrickson and Frank 16 and Tao and Frank 17 analyzed migrational and rotational sampling in an aromatic homopolymer and discussed solutions in the limit of slow rotational transitions.…”

Section: Introductionsupporting

confidence: 57%

Excitation energy transport and conformational-librational motion in chains

Pálszegi

Mollay

Kauffmann

1998

The Journal of Chemical Physics

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Experimental studies of peptide bonds: Identification of the C 7 eq conformation of the alanine dipeptide analog N-acetyl-alanine N ′ -methylamide from torsion-rotation interactions Incoherent electronic excitation transport ͑EET͒ along chromophore-sites has been studied in the presence of conformational and librational motion by using a rotor chain model as the mobile vehicle. The time-evolution of the electronic site excitation probability vector P exc (t) averaged by conformational-librational dynamic disorder has been calculated by a second-order cumulant expansion ͑CE͒ approach. A master equation for conformer distributions in torsional space has been used ͓G. J. Moro, J. Chem. Phys. 94, 8577 ͑1991͒ and J. Chem. Phys. 97, 5749 ͑1992͔͒ to describe the coupled, motional stochastic dynamics of a rotor chain. Based upon this model, the correlation functions of excitation transfer rates, important for the calculation of the second cumulants of the stochastic excitation transfer rate matrices, have been constructed. A simplified procedure for evaluating the correlation functions for the L steep minima of torsional angle-dependent symmetrical potentials of nearest-neighbor rotor-pairs and for a Gaussian distribution of torsional angles displacement has been carried out. By using analytical fits to the second cumulants, the evolution of excitation energy transfer has been calculated in terms of the averaged site probabilities ͗P exc (t)͘ for chromophores, substituted to the L-fold symmetric rotors. The calculated profiles show a pronounced dependence on the curvature ratio in the saddle point of the rotor pair potential, on the number of the pair potential minima as well as on the average of the mean-square deviation of torsional angles from the stable conformations.

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Section: Introductionsupporting

confidence: 57%

Excitation energy transport and conformational-librational motion in chains

Pálszegi

Mollay

Kauffmann

1998

The Journal of Chemical Physics

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“…We have examined the local chain dynamics of various polymers in dilute solution by the fluorescence depolarization method. [9][10][11][12][13][14] So far we have concentrated our attention on the center of the main chain. We have compared the local chain mobility between polymers, which differ in molecular structure 9,10,12 or stereoregularity.…”

Section: Introductionmentioning

confidence: 99%

“…We have compared the local chain mobility between polymers, which differ in molecular structure 9,10,12 or stereoregularity. 14 Since the dynamic properties of polymer chains depend on the position of polymer chains, the information on the polymer chain end is indispensable. It is interesting to compare the chain mobility between the chain center and the chain end on the same linear polymer.…”

Section: Introductionmentioning

confidence: 99%

Local Motion of Oligo- and Polystyrene Chain End Studied by the Fluorescence Depolarization Method

et al. 1999

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Local motion of the oligo-and polystyrene chain end in dilute solution was examined by the fluorescence depolarization method. The molecular weight of the sample varied from 5.1 × 10 2 to 2.5 × 10 4 . The relaxation time of local motion, Tm, in benzene solution increased with molecular weight and reached an asymptotic value at MW ) 2 × 10 3 with Tm = 0.3 ns. In ethyl acetate, which is a poorer solvent than benzene, Tm became constant at a higher molecular weight than in benzene, and the asymptotic relaxation time was longer than that in benzene. We proposed that the difference in the relaxation time and in its molecular weight dependence between the two solutions may result from the local potential for the conformational transition of the main chain bond, rather than the segment density. In comparison with the relaxation time for the polystyrene chain center, both the critical molecular weight and the asymptotic relaxation time for the chain end were about 1 order smaller than those for the chain center. This indicates that the mobility of a linear polymer chain end is sufficiently different from that of its chain center.

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“…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%

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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Local Chain Motion of Isotactic and Syndiotactic Poly(methyl methacrylate)s Studied by the Fluorescence Depolarization Method

Cited by 16 publications

References 14 publications

Excitation energy transport and conformational-librational motion in chains

Excitation energy transport and conformational-librational motion in chains

Local Motion of Oligo- and Polystyrene Chain End Studied by the Fluorescence Depolarization Method

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

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