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Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
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Microstructure, local dynamics, and flow behavior of colloidal suspensions with weak attractive interactions.
Clara Weis1, Claude Oelschlaeger1, Dick Dijkstra2
1Karlsruhe Institute for Technology (KIT), Institute for Mechanical Process Engineering and Mechanics, Applied Mechanics, Karlsruhe, 76131, Germany.
Scientific Reports
|September 23, 2016
Summary
Weak attraction in colloidal suspensions significantly alters their flow properties. Increasing attraction can lead to fluid, crystalline, gel, or arrested states, impacting viscosity and structure.
Area of Science:
- Colloid and Interface Science
- Soft Matter Physics
- Rheology
Background:
- Dense colloidal suspensions are crucial in various industries.
- Understanding their rheological behavior under weak attraction is key.
- Short-range repulsive interactions are common in stabilizing such systems.
Purpose of the Study:
- To investigate the impact of weak depletion attraction on dense colloidal suspensions.
- To reveal structural changes and rheological properties using micro- and macrorheology.
- To explore the transition from fluid to gel and crystalline states.
Main Methods:
- Utilized aqueous polymer dispersions as a model system.
- Employed multiple particle tracking (MPT) for micro- and macrorheological analysis.
- Studied systems with weak depletion attraction (Ψdep ≈ 1-10 kBT).
Main Results:
- Viscosity increases with attraction below the freezing point, leading to fluid, crystalline, and gel states.
- Above freezing, attraction initially reduces viscosity (large crystals) then increases it (dense crystal networks).
- Micro-crystal modulus decreases with attraction; arrested states show heterogeneities and cage trapping.
Conclusions:
- Weak depletion attraction profoundly influences colloidal suspension rheology and structure.
- MPT is effective in characterizing structural changes in these complex systems.
- Particle interactions dictate the transition between fluid, crystalline, gel, and arrested states.
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