1991 Fiscal Year Final Research Report Summary
Studies of the Excluded-Volume Effects and Chain Conformations of Oligomers and Polymers in Dilute Solutions.
| Project/Area Number |
02453100
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
高分子物性・高分子材料（含機械材料）
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
EINAGA Yoshiyuki Kyoto University, Polymer Chemistry, associate Professor, 工学部, 助教授 (70028257)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Excluded-Volume Effect / Gyration-Radius Expansion Factor / Viscosity-Radius Expansion Factor / Helical Wormlike Chain / Chain Stiffness / Quasi-Two-Parameter Theory / Second Virial Coefficient / Interpenetration Function |
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| Research Abstract |
In this work, we have studied the excluded-volume effects on dilute solution properties of atactic polystirene with fixed stereochemical composition (the fraction of racemic diads f_r=0.59), atactic poly(methyl methacrylate) with f_r=0.79, and pol13EA\ : yisobutylene with fixed structure of chain ends over a wide range of molecular weight M from oligomers and polymers. The obtained findings are summarized as follows :
1)A quasi-two-parameter scheme is valid for the gyration-radius expansion factor alpha_s. That is, alpha_s may be expressed as a function only of the scaled excluded-volume parameter * defined in the Yamakawa-Stockmayr-Shimada theory that takes a13EA\ : ccount of the effects of excluded-volume and chain stiffness on the basis of the helical wormlike (HW) chain. The conventional two-parameter theory does not hold for alpha_s because of chain stiffness. The effect of chain stiffness remains large ev13EA\ : en for M > 10^6.
2)The quasi-two-parameter scheme is also valid for th
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e viscosity-radius expansion factor alpha_<eta> as in the case of alpha_s. The effect of chain stiffness on alpha_<eta> also remains large even for M > 10^6. The draining effect does not appear in13EA\ : alpha_<eta>, if it is not observed in the intrinsic viscosity [eta]_<(〕SY.horizontally divided circle.〔)> at THETA.
3)The interpenetration function psi appearing in the second virial coefficient A_2 is not a function only of alpha_s, indicating that neither the conventional- nor the quasi-two-parameter scheme is valid for psi. psi depends separately on M and on13EA\ : the excluded-volume strength because of chain stiffness. The experimental results for psi are semi-quantitatively explained by the Yamakawa theory that takes account of the effect of chain stiffness on A_2.
4)For small M, the effect of chain ends on A_2 is significant in both THETA and good solvents. The effect cannot be neglected even for relatively large M up to ca. 10^5. The observed M dependence of A_2 is quantitatively expressed by the Yamakawa13EA\ : theory that takes account of that effect on A_2. Less
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