The concentration fluctuations in polymer-mixed solvent systems

Vavra, J.; Antalik, J.

doi:10.1016/s0032-3861(97)00198-5

Cited by 4 publications

(3 citation statements)

References 7 publications

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“…This compatibility enhancement of the mixed solvent due to the presence of polymer is quite spectacular since v c 9 increases by practically an order of magnitude upon addition of a small amount of polymer. Qualitatively, this behavior is consistent with the observation made on PS/ (benzene + cyclohexane) by Varra and Autalik 29) . These authors found that a strong interaction between PS and non solvents (cyclohexane) could lead to a reduced solvent-solvent interaction and hence a compatibility enhancement of the mixture.…”

Section: The Scattering Functionssupporting

confidence: 92%

“…(29). This sign is determined by the relative magnitude of v BP as compared to If v BP is as high as 1.5 expressing a large polymer-solvent B incompatibility, a small amount of polymer would result into a large increase of Dv c meaning that the solvents A and B prefer to remain mixed rather than adsorbing on the polymer even though the interaction v AB chosen in plotting this figure (v AB = 1) is relatively high.…”

Section: The Scattering Functionsmentioning

confidence: 99%

“…Considering the q = 0 limit, one can make similar remarks as those following Eq. (29), except that the concentration range of polymer is not limited to infinite dilute solutions and the polymer concentration range is extended to higher values in investigating the variation of the interaction parameter v9 c as a function of polymer concentration b P .…”

Section: The Scattering Functionsmentioning

confidence: 99%

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Mean-field-theory for polymers in mixed solvents. Thermodynamic and structural properties

Negadi¹,

Sans-Pennincks²,

Benmouna³

et al. 1999

Macromol. Theory Simul.

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SUMMARY: Theoretical aspects of polymers in mixed solvents are considered using the Edwards Hamiltonian formalism. Thermodynamic and structural properties are investigated and some predictions are made when the mixed solvent approaches criticality. Both the single and the many chain problems are examined. When the mixed solvent is near criticality without solute, addition of a small amount of polymers shifts the criticality towards either enhanced compatibility or induced phase separation depending upon the value of the parameter describing the interaction asymmetry of the solvents with respect to the polymer. The polymersolvent effective interaction parameter increases strongly when the solvent mixture approaches criticality. Accordingly, the apparent excluded volume parameter decreases and may vanish or even become negative. Consequently, the polymer undergoes phase transition from a swollen state to an unperturbed state or even takes a collapsed configuration. The effective potential acting on a test chain in strong solutions is calculated and the concept of Edwards screening discussed. Structural properties of ternary mixtures of polymers in mixed solvents are investigated within the Edwards Hamiltonian model. It is shown that the effective potential on a test chain in strong solutions could be written as an infinite series expansion of terms describing interactions via one chain, two chains etc. This summation can be performed following a similar scheme as in the Ornstein-Zernike series expansion.

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Section: The Scattering Functionssupporting

confidence: 92%

Section: The Scattering Functionsmentioning

confidence: 99%

Section: The Scattering Functionsmentioning

confidence: 99%

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