Oligomere in verdünnten Lösungen

Sotobayashi, Hideto; Springer, Jürgen

doi:10.1007/bfb0051142

Cited by 23 publications

(3 citation statements)

References 174 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is interesting to see that in some cases 2, exhibits a maximum in the oligomer region. In this connection, we must note that such behavior of A2 was already observed a long time ago for a-PS17 and atactic poly(methyl methacrylate) (a-PMMA),18 though in good solvents, and it was given an explanation by Sotobayashi and Springer,19 who considered the effect of chain ends on the enthalpy term of A2. Thus it is clear that both effects of chain stiffness and chain ends on A2 in general become significant in the oligomer region, in which an analysis of experimental data for A2 should be based on eq 23.…”

Section: Effects Of Chain Endsmentioning

confidence: 63%

See 1 more Smart Citation

On the theory of the second virial coefficient for polymer chains

Yamakawa¹

1992

Macromolecules

100

View full text Add to dashboard Cite

The theory of the second virial coefficient A2 for flexible polymers is reconsidered in order to explain two observations inconsistent with the two-parameter theory prediction. One is the decrease in the interpenetration function with increasing molecular weight M in good solvents even in the ordinary range of M in which the unperturbed mean-square radius of gyration is proportional to M. The other is the nonvanishing of A2 for small M at the temperature. It is shown that the first observation may be explained by considering effects of chain stiffness on and also on the expansion factor as, which remain rather large even in the range of M above, although vanishingly small for very large M, according to the Yamakawa-Stockmayer-Shimada theory for the wormlike and helical wormlike chains. Therefore the theory also predicts that the increase in with increasing solvent power depends in general on M. The second may be explained by considering possible effects of chain ends. Both effects are then analyzed by a comparison with experiment. Thus it is emphasized that the two-parameter theory should be considered a limiting law for extremely large M.

show abstract

Section: Effects Of Chain Endsmentioning

confidence: 63%

“…+ (8 -13.53L"1 + 0.2804L"V/2 + (-0.3333 1 + 5.724 2 -0.7974L"3)x"1/2 + (-0.3398L'2 + 0.7146L"3)z"3/2 (19) with…”

Section: Effects Of Chain Stiffnessmentioning

confidence: 99%

On the theory of the second virial coefficient for polymer chains

Yamakawa¹

1992

Macromolecules

100

View full text Add to dashboard Cite

show abstract

“…References and Notes (1) (3) Skolnick, J.; Yaris, R. Macromolecules 1983, 16, 266. (4) Pant, B. B.; Skolnick, J.; Yaris, R. Macromolecules 1985, 18, 253.…”

mentioning

confidence: 99%

Molecular weight dependence of the second virial coefficient for linear flexible polymers in good solvents

Fujita¹,

Norisuye²

1985

Macromolecules

View full text Add to dashboard Cite

Monte‐carlo‐rechnungen an makromolekülmodellen. 2. Mitt.: Quadratischer mittelwert des trägheitsradius und expansionskoeffizient

Bruns

1970

Makromol. Chem.

View full text Add to dashboard Cite

ZUSAMMENFASSUNG :Fur zwei gitterfreie Modelle wurden mit Hilfe der Monte-Carlo-Rechnung unter Beriicksichtigung des ,,ausgeschlossenen Volumens'& Zufallsketten erzeugt, die als vereinfachtes Bild h e a r e r Polymermolekiile dienen konnen. Die Ketten bestanden aus maximal etwa 100 Struktureinheiten. Die Abhangigkeit des mittleren Quadrats des Tragheitsradius von der Bindungszahl wurde bestimmt und dafur fur n > 15 3 = 0,229 n1~237 bzw. 9 = 0,185 n1,250 gefunden. Das Verhaltnis @/? nahert sich asymptotisch einem Wert von ca. 6,s.Sechs aus der Literatur bekannte Beziehungen zwischen dem Expansionskoeffizienten c( und dem Wechselwirkungsparameter z wurden getestet. Fur den untersuchten Bereich erwiesen sich die Naherung von FIXMAN, die allerdings modifiziert werden muate, und die von JAMES als die besten. Letztere besitzt jedoch den Nachteil, daD ihre Anwendung fur langere Ketten problematisch ist, wahrend die Gleichung nach FIXMAN, wie Untersuchungen an Gittermodellen gezeigt haben, auch dort giiltig ist. Die GroDe des ,,ausgeschlossenen Volumens" und des Verhaltnisses von der Segmentzahl zur Zahl der Struktureinheiten wurde anhand der Ergebnisse diskutiert. S, U' M M A R Y :Two nonlattice non-intersecting random walks have been used as a model for the linear polymer chain with excluded volume. The chains consisted of -100 structural units a t most. The dependence of the mean-square radius of gyration on the number of structural units has been investi dted and the relations 9 = 0,229 n1,237 and 9 = 0,185 111,250 have been found for n > 1 Z F h e ratio @/? approaches asymptotically a value of 6,s. Six known relations between the expansion coefficient 9c and the segment interaction parameter z have been teste_d.lFor the range investigated the approximation of FIXMAN, which had to be slightly modified, and that of JAMES were the best of them. The latter, however, has the disadvantage of being problematic in its applicability to long chains, while the equation of FIXMAN is also valid in this range as shown by investigations of lattice models. The size of the excluded volume and the ratio of the number of segments to the number of structural units has been discussed in view of the results.

show abstract

Oligomere in verdünnten Lösungen

Cited by 23 publications

References 174 publications

On the theory of the second virial coefficient for polymer chains

On the theory of the second virial coefficient for polymer chains

Molecular weight dependence of the second virial coefficient for linear flexible polymers in good solvents

Monte‐carlo‐rechnungen an makromolekülmodellen. 2. Mitt.: Quadratischer mittelwert des trägheitsradius und expansionskoeffizient

Contact Info

Product

Resources

About