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Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
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Phase separation and the 'coffee-ring' effect in polymer-nanocrystal mixtures
Joseph B Miller1, Austin C P Usselman, Rebecca J Anthony
1Department of Physics, North Dakota State University, Fargo, North Dakota, USA. erik.hobbie@ndsu.edu.
Soft Matter
|March 22, 2014
Summary
The polymer
Area of Science:
- Colloid and Interface Science
- Materials Chemistry
- Fluid Dynamics
Background:
- The coffee-ring effect causes non-uniform deposition during solvent evaporation.
- Liquid-liquid phase separation influences drying dynamics in complex fluid mixtures.
- Controlling deposition patterns is crucial for material fabrication.
Purpose of the Study:
- To investigate the interplay between the coffee-ring effect and liquid-liquid phase separation.
- To understand how polymer size affects drying instabilities in nanocrystal suspensions.
- To inform deposition processes for more uniform material coatings.
Main Methods:
- Studied ternary mixtures of toluene, polystyrene (PS), and silicon nanocrystals (SiNCs).
- Employed real-space imaging and spectroscopic techniques.
- Compared experimental results with simulations and binodal curves.
Main Results:
- Polymer molecular weight significantly impacts phase separation and drying dynamics.
- Observed a direct correlation between polymer size and the coffee-ring effect.
- Demonstrated how polymer size influences the flow field at the contact line.
Conclusions:
- Polymer size is a critical factor in controlling drying instabilities.
- Low-molecular-weight polymers can reduce deposition irregularities.
- Findings enable more accurate computational models for complex fluid drying.
