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Arrested fluid-fluid phase separation in depletion systems: Implications of the characteristic length on gel formation and rheology

Research output: Contribution to journalArticle

  • J. C. Conrad
  • H. M. Wyss
  • V. Trappe
  • S. Manley
  • K. Miyazaki
  • L. J. Kaufman
  • Andrew B Schofield
  • D. R. Reichman
  • D. A. Weitz

Related Edinburgh Organisations

Original languageEnglish
Pages (from-to)421-438
Number of pages18
JournalJournal of rheology
Volume54
Issue number2
DOIs
Publication statusPublished - 2010

Abstract

We investigate the structural, dynamical, and rheological properties of colloid-polymer mixtures in a volume fraction range of phi=0.15-0.35. Our systems are density-matched, residual charges are screened, and the polymer-colloid size ratio is similar to 0.37. For these systems, the transition to kinetically arrested states, including disconnected clusters and gels, coincides with the fluid-fluid phase separation boundary. Structural investigations reveal that the characteristic length, L, of the networks is a strong function of the quench depth: for shallow quenches, L is significantly larger than that obtained for deep quenches. By contrast, L is for a given quench depth almost independent of phi; this indicates that the strand thickness increases with phi. The strand thickness determines the linear rheology: the final relaxation time exhibits a strong dependence on phi, whereas the high frequency modulus does not. We present a simple model based on estimates of the strand breaking time and shear modulus that semiquantitatively describes the observed behavior.

    Research areas

  • colloids, phase separation, polymer blends, polymer gels, quenching (thermal), rheology, shear modulus, COLLOID-POLYMER MIXTURES, EQUILIBRIUM CLUSTER FORMATION, STOKES-RAMAN SCATTERING, SPINODAL DECOMPOSITION, NONUNIFORM SYSTEM, MODEL SYSTEM, FREE ENERGY, SUSPENSIONS, BEHAVIOR, GELATION

ID: 1274791