Journal article

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

  • Conrad, J. C. Department of Physics and SEAS, Harvard University, Cambridge, USA - Department of Chemical and Biomolecular Engineering, University of Houston, USA
  • Wyss, H. M. Department of Physics and SEAS, Harvard University, Cambridge, USA - Eindhoven University of Technology, ICMS & WTB, Eindhoven, the Netherlands
  • Trappe, Véronique Department of Physics, University of Fribourg, Switzerland
  • Manley, S. Department of Physics and SEAS, Harvard University, Cambridge, USA - Institute of Physics of Biological Systems, EPFL, Lausanne, Switzerland
  • Miyazaki, K. Department of Chemistry, Columbia University, New York, USA - Institute of Physics, University of Tsukuba, Japan
  • Kaufman, L. J. Department of Chemistry, Columbia University, New York, USA
  • Schofield, A. B. Department of Physics, University of Edinburgh, Edinburgh United Kingdom
  • Reichman, D. R. Department of Chemistry, Columbia University, New York, USA
  • Weitz, D. A. Department of Physics and SEAS, Harvard University, Cambridge, USA
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    12.04.2010
Published in:
  • Journal of Rheology. - 2010, vol. 54, no. 2, p. 421-438
English We investigate the structural, dynamical, and rheological properties of colloid-polymer mixtures in a volume fraction range of Φ=0.15–0.35. Our systems are density-matched, residual charges are screened, and the polymer-colloid size ratio is ~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 Φ; this indicates that the strand thickness increases with Φ. The strand thickness determines the linear rheology: the final relaxation time exhibits a strong dependence on Φ, 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.
Faculty
Faculté des sciences
Department
Physique
Language
  • English
Classification
Physics
License
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Persistent URL
https://folia.unifr.ch/unifr/documents/301521
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