Dynamic shear behavior of poly(γ‐benzyl <scp>L</scp>‐glutamate), poly(<scp>D</scp>,<scp>L</scp>‐propylene oxide), and poly(ethyl vinyl ether)

Saba, Rabbira Garba; Sauer, J. A.; Woodward, A. E.

doi:10.1002/pol.1963.100010502

Cited by 18 publications

(17 citation statements)

References 19 publications

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“…A similar conclusion has recently been drawn for a gel system consisting of cross-linked triols of varying complexity [16,17]. The result is also in accord with some previous suggestions for the origin of the relaxation in PPG [18,19]. Furthermore, the activation energy of the relaxations found in our system (0:29-0:34 eV) supports an interpretation in terms of cooperative movements.…”

supporting

confidence: 92%

Influence of Chain Length on theα−βBifurcation in Oligomeric Glass Formers

et al. 2005

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A series of oligo(propylene glycol) dimethyl ethers has been investigated using dielectric spectroscopy in order to relate features of the glass transition dynamics to the number of monomer units N in the chain. The results show that (i) when scaled with the glass transition temperature, the beta relaxations systematically become faster for larger N whereas the alpha relaxations display nearly identical temperature evolutions, i.e., the alpha-beta bifurcation shifts towards shorter times for larger N, (ii) the bifurcation scenario displays a crossover in behavior at N approximately 10 monomer units, signaling the transition from oligomeric to polymeric behavior, and (iii) the beta relaxation has a cooperative nature.

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supporting

confidence: 92%

Influence of Chain Length on theα−βBifurcation in Oligomeric Glass Formers

et al. 2005

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“…Let bo be the intrinsic optical anisotropy of the perfectly rigid molecules, which one could measure by extrapolation 23,1991 polarized experiments at low concentration in this system. Agreement with the Benoit-Stockmayer theory is fully consistent with polarized scattering results that confirm the Onsager or DSO predictions; the essential ingredient in all these theories is careful treatment of excluded volume.…”

Section: Static Light Scattering Results and Discussionmentioning

confidence: 99%

“…24, No. 23,1991 account for the shift from the macroscopic properties that SLS and DLS observe at low qL to the more microscopic viewpoint at high qL.…”

Section: (1-u / U * )mentioning

confidence: 95%

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Thermodynamic and dynamic behavior of semiflexible polymers in the isotropic phase

DeLong¹,

Russo²

1991

Macromolecules

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Static and dynamic light scattering measurements have been made for concentrated isotropic solutions of the semiflexible polymer poly(y-benzyl a,L-glutamate) (PBLG) dispersed in Nfl-dimethylformamide (DMF). Characterization of the fractionated polymers shows them to be reasonably monodisperse and quite stiff. The osmotic modulus, (au/ac),, increases with concentration at very nearly the rate predicted long ago by Onsager, but sharp decreases are observed as the nematic transition is approached. The static correlation length decreases with concentration in the fashion proposed by Shimada, Doi, and Okano (J. Chem. Phys. 1988, 88, 2815 at low to moderate concentrations. At larger concentrations, the apparent correlation length decreases less rapidly than predicted and then actually increases. A a result, the scaling relation first proposed by de Gennes, Pincus, Velasco, and Brochard (J. Phys. (Paris) 1976,37, 1461) is not obeyed precisely. The depolarized light scattering intensity, although quite weak in dilute solutions, increases markedly with concentration. The apparent molecular optical anisotropy increases in a fashion that is at least qualitatively consistent with the theory first proposed by Benoit and Stockmayer (J. Phys. Radium 1956,17,21). The average decay rates of intensity-intensity autocorrelation functions display the unusual angular dependence predicted by the random phase theory of Doi, Shimada, and Okano (J. Chem. Phys. 1988, 88,4070). But the increase in apparent mutual diffusion coefficient is only about 113 of that expected if the translational self-diffusion parallel to the rod axis is constant. Mutual friction coefficients increase monotonically with concentration. The initial rate of increase is consistent with the theory of Peterson (J. Chem. Phys. 1964, 40, 2640. It was possible to scale the friction coefficients with concentration using no adjustable parameters. While single-exponential autocorrelation functions were observed at low angles and concentrations, the decay spectrum at high concentrations contains at least three decay modes. Two of these exhibit qualitatively the behavior predicted by Shimada, Doi, and Okano (J. Chem. Phys. 1988, 88, 7181), with some exceptions.

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“…A small relaxation peak can be observed in the temperature vicinity of -l00°C for any one sample. On the basis of previous studies/- 6 this can be ascribed to the local motion of the side chain and is not considered further in this paper. All two relaxation peaks.…”

mentioning

confidence: 96%

Dielectric Study on Cooperative Motion of Side Chain of Copoly(γ-methyl L-glutamate, γ-p-chlorobenzyl L-glutamate) in the Solid State

Yagihara

Hikichi

1981

Polym J

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ABSTRACT:Dielectric measurements on copoly(y-methyl L-glutamate, y-p-chlorobenzyl Lglutamate) [copoly(MLG, pCIBLG)] were performed in the frequency range of 0.03 to 300kHz and over the temperature range from -150 to + 130°C in order to study the side-chain motion. Two side-chain relaxations related respectively to MLG and pClBLG residues were observed. The results imply that there exists a cooperative motion of the side chains of poly( a-amino acid), though not as much as the main-chain motion of conventional amorphous polymers. The relaxation related to MLG residues is caused by clusters of MLG residues that are not affected by interactions between pCIBLG residues. KEY WORDSA number of poly(a-amino acid)s take on an ahelical form in the solid state.' It Is well known that side chains have great influence upon the conformation and physical properties of these polymers. 2 Many studies 2 -11 have been made on the side-chain motion of poly(a-amino acid), and it has been pointed out that a large scale displacement of the whole side chain occurs cooperatively.Dielectric 3 -5 and mechanical 2 • 6 · 7 measurements of poly(a-amino acid)s reveal a 'side-chain relaxation' caused by micro-Brownian motion throughout the side chain. It has also been reported that copoly(y-methyl L-glutamate, y-benzyl L-glutamate)s[copoly(MLG, BLG)s] take on the a-helical form in the solid state and show a single sidechain relaxation process brought about by a mechanism the same as that for the respective homopolymers.3 These facts support the proposition that the side-chain motion of poly( a-amino acid) occurs cooperatively, and thus seems similar to the mainchain motion of conventional amorphous polymers. This was also confirmed by a dielectric study on L-lysine, }'-benzyl Lglutamatc).4 No other dielectric studies on the sidechain motion of copoly(a-amino acid) have been reported.It seems, however, that the side-chain motion of a-helical poly( a-amino acid) is less cooperative than that of the main-chain motion of a conventional amorphous polymer, since the scale of the molecular rearrangement for the side-chain motion of the poly(a-amino acid) is probably smaller than the main-chain motion of the conventional amorphous polymer. No evidence for this has as yet been provided experimentally. In the present work, we carried out dielectric measurements on copoly-(y-methyl L-glutamate, y-p-chlorobenzyl L-giutamate)[copoly(MLG, pCIBLG)] in order to clarify the cooperativity of the side-chain motion of poly(a-amino acid). The dielectric behavior of PMLG 3 and PpCIBLG 5 is comparatively different, since the pCIBLG residue and its dipole moment are larger than those of the MLG residue. We examined the composition dependence of the dielectric behavior for these copolymers in detail.579

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Dynamic shear behavior of poly(γ‐benzyl L‐glutamate), poly(D,L‐propylene oxide), and poly(ethyl vinyl ether)

Cited by 18 publications

References 19 publications

Influence of Chain Length on theα−βBifurcation in Oligomeric Glass Formers

Influence of Chain Length on theα−βBifurcation in Oligomeric Glass Formers

Thermodynamic and dynamic behavior of semiflexible polymers in the isotropic phase

Dielectric Study on Cooperative Motion of Side Chain of Copoly(γ-methyl L-glutamate, γ-p-chlorobenzyl L-glutamate) in the Solid State

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