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Viscoelasticity and Stokes-Einstein relation in repulsive and attractive colloidal glasses
Antonio M Puertas1, Cristiano De Michele, Francesco Sciortino
1Group of Complex Fluid Physics, Departamento de Física Aplicada, Universidad de Almería, 04120 Almeria, Andalucía, Spain.
The Journal of Chemical Physics
|October 16, 2007
Summary
This study numerically investigates colloidal suspension viscosity, revealing power-law divergences near repulsive and attractive glass transitions. The Stokes-Einstein relation breaks down, especially for attractive glasses.
Area of Science:
- Colloidal Science
- Soft Matter Physics
- Computational Materials Science
Background:
- Colloidal suspensions exhibit complex viscoelastic behaviors influenced by inter-particle forces and density.
- Understanding glass transitions in these systems is crucial for predicting material properties.
Purpose of the Study:
- To numerically investigate the viscoelastic behavior of colloidal suspensions with both repulsive and attractive interactions.
- To explore viscosity changes near repulsive and attractive glass transitions and in reentrant regions.
- To analyze the validity of the Stokes-Einstein relation in these transition regimes.
Main Methods:
- Numerical simulations comparing Newtonian and Brownian dynamics.
- Analysis of viscosity and its frequency dependence.
- Mode-coupling calculations to understand length-scale contributions.
Main Results:
- Viscosity exhibits power-law divergence approaching glass lines, consistent with density fluctuation data.
- Results are independent of microscopic dynamics (Newtonian vs. Brownian).
- A significant breakdown of the Stokes-Einstein relation is observed, particularly for attractive glasses.
Conclusions:
- The study provides insights into the scaling behavior of viscosity near colloidal glass transitions.
- Microscopic dynamics do not affect the observed macroscopic viscoelastic properties.
- The breakdown of the Stokes-Einstein relation highlights differences between repulsive and attractive glass formation.
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