Über die Konzentrations- und Temperaturabhängigkeit des Diffusionskoeffizienten in hochmolekularen Lösungen

Rehage, G.; Ernst, O.

doi:10.1007/bf01500188

Cited by 23 publications

(1 citation statement)

References 4 publications

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“…A similar change in k d was observed in solutions of polystyrene in cyclohexane, 25,26 decahydronaphthalene, 24 and poly(R-methylstyrene) in cyclohexane 27 and ascribed to the change in k f . A uniform of the chains in the solution would not make k f so large, however.…”

Section: Single-mode Concentration Range At Low Concentrations We Can...supporting

confidence: 72%

Dynamic Light Scattering from Semidilute Solutions of a Styrene−Acrylonitrile Random Copolymer

Zheng¹,

Teraoka²

2001

Macromolecules

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Dynamics of a random copolymer, poly(styrene-co-acrylonitrile), in dilute and semidilute solutions was studied by using dynamic light scattering. The solvent used was a mixture of dioxane and acetonitrile (ACN). The mixing ratio and the temperature were changed to provide the copolymer with various solvent conditions that range from a good to a Θ solvent. At low ACN contents, the autocorrelation function of the light scattering intensity had a single relaxation mode. Its diffusion changed from the mutual diffusion to the cooperative diffusion of entangled chains in the good solvent as the concentration c increased. At high ACN contents (near Θ), the diffusion coefficient decreased to 1 /3 of the dilute solution value and the scattering intensity increased almost linearly with c, before the diffusion coefficient turned to increase as ∼c and the scattering intensity to decrease as ∼c -1 , indicating the cooperative diffusion of entangled Θ chains. In this high concentration range, the autocorrelation function exhibited a slow diffusion mode as well. A high friction coefficient and an extended near-linear range in the scattering intensity, especially at low temperatures, suggest dynamic clustering of chains upon increasing the concentration.

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