Spinodal decomposition of asymmetric binary fluids in a micro-Couette geometry simulated with molecular dynamics

A.K. Thakre, Wouter K. den Otter, J.T. Padding, Willem J. Briels

Research output: Contribution to journalArticleAcademicpeer-review

3 Citations (Scopus)

Abstract

The spinodal decomposition of quenched polymer/solvent and liquid-crystal/solvent mixtures in a miniature Taylor–Couette cell has been simulated by molecular dynamics. Three stacking motifs, each reflecting the geometry and symmetry of the cell, are most abundant among the fully phase separated stationary states. At zero or low angular velocity of the inner cylindrical drum, the two segregated domains have a clear preference for the stacking with the lowest free energy and hence the smallest total interfacial tension. For high shear rates, the steady state appears to be determined by a minimum dissipation mechanism, i.e., the mixtures are likely to evolve into the stacking demanding the least mechanical power by the rotating wall. The partial slip at the polymer-solvent interfaces then gives rise to a new pattern: A stack of three concentric cylindrical shells with the viscous polymer layer sandwiched between two solvent layers. Neither of these mechanisms can explain all simulation results, as the separating mixture easily becomes kinetically trapped in a long-lived suboptimal configuration. The phase separation process is observed to proceed faster under shear than in a quiescent mixture.
Original languageEnglish
Article number074505
Number of pages13
JournalJournal of chemical physics
Volume129
Issue number074505
DOIs
Publication statusPublished - 2008

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Spinodal decomposition
binary fluids
Molecular dynamics
molecular dynamics
decomposition
Polymers
Fluids
Geometry
geometry
polymers
shear
Liquid Crystals
drums
cylindrical shells
Angular velocity
angular velocity
cells
Phase separation
Shear deformation
Free energy

Keywords

  • METIS-249990
  • IR-59914

Cite this

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title = "Spinodal decomposition of asymmetric binary fluids in a micro-Couette geometry simulated with molecular dynamics",
abstract = "The spinodal decomposition of quenched polymer/solvent and liquid-crystal/solvent mixtures in a miniature Taylor–Couette cell has been simulated by molecular dynamics. Three stacking motifs, each reflecting the geometry and symmetry of the cell, are most abundant among the fully phase separated stationary states. At zero or low angular velocity of the inner cylindrical drum, the two segregated domains have a clear preference for the stacking with the lowest free energy and hence the smallest total interfacial tension. For high shear rates, the steady state appears to be determined by a minimum dissipation mechanism, i.e., the mixtures are likely to evolve into the stacking demanding the least mechanical power by the rotating wall. The partial slip at the polymer-solvent interfaces then gives rise to a new pattern: A stack of three concentric cylindrical shells with the viscous polymer layer sandwiched between two solvent layers. Neither of these mechanisms can explain all simulation results, as the separating mixture easily becomes kinetically trapped in a long-lived suboptimal configuration. The phase separation process is observed to proceed faster under shear than in a quiescent mixture.",
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journal = "Journal of chemical physics",
issn = "0021-9606",
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Spinodal decomposition of asymmetric binary fluids in a micro-Couette geometry simulated with molecular dynamics. / Thakre, A.K.; den Otter, Wouter K.; Padding, J.T.; Briels, Willem J.

In: Journal of chemical physics, Vol. 129, No. 074505, 074505, 2008.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Spinodal decomposition of asymmetric binary fluids in a micro-Couette geometry simulated with molecular dynamics

AU - Thakre, A.K.

AU - den Otter, Wouter K.

AU - Padding, J.T.

AU - Briels, Willem J.

PY - 2008

Y1 - 2008

N2 - The spinodal decomposition of quenched polymer/solvent and liquid-crystal/solvent mixtures in a miniature Taylor–Couette cell has been simulated by molecular dynamics. Three stacking motifs, each reflecting the geometry and symmetry of the cell, are most abundant among the fully phase separated stationary states. At zero or low angular velocity of the inner cylindrical drum, the two segregated domains have a clear preference for the stacking with the lowest free energy and hence the smallest total interfacial tension. For high shear rates, the steady state appears to be determined by a minimum dissipation mechanism, i.e., the mixtures are likely to evolve into the stacking demanding the least mechanical power by the rotating wall. The partial slip at the polymer-solvent interfaces then gives rise to a new pattern: A stack of three concentric cylindrical shells with the viscous polymer layer sandwiched between two solvent layers. Neither of these mechanisms can explain all simulation results, as the separating mixture easily becomes kinetically trapped in a long-lived suboptimal configuration. The phase separation process is observed to proceed faster under shear than in a quiescent mixture.

AB - The spinodal decomposition of quenched polymer/solvent and liquid-crystal/solvent mixtures in a miniature Taylor–Couette cell has been simulated by molecular dynamics. Three stacking motifs, each reflecting the geometry and symmetry of the cell, are most abundant among the fully phase separated stationary states. At zero or low angular velocity of the inner cylindrical drum, the two segregated domains have a clear preference for the stacking with the lowest free energy and hence the smallest total interfacial tension. For high shear rates, the steady state appears to be determined by a minimum dissipation mechanism, i.e., the mixtures are likely to evolve into the stacking demanding the least mechanical power by the rotating wall. The partial slip at the polymer-solvent interfaces then gives rise to a new pattern: A stack of three concentric cylindrical shells with the viscous polymer layer sandwiched between two solvent layers. Neither of these mechanisms can explain all simulation results, as the separating mixture easily becomes kinetically trapped in a long-lived suboptimal configuration. The phase separation process is observed to proceed faster under shear than in a quiescent mixture.

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JO - Journal of chemical physics

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