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Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
Shape-induced dispersion of colloids in anisotropic fluids
F Mondiot1, S Prathap Chandran, O Mondain-Monval
1Université de Bordeaux, Centre de Recherche Paul Pascal-CNRS, 115 Avenue Albert Schweitzer, Pessac, 33600, France.
Physical Review Letters
|April 7, 2010
Summary
Micrometer-sized ellipsoidal particles in liquid crystals aggregate, but transition to a non-aggregating state above a specific aspect ratio. This unexpected behavior in particle self-assembly was experimentally observed and theoretically analyzed.
Area of Science:
- Soft Matter Physics
- Colloidal Science
- Materials Science
Background:
- Micrometer-sized prolate ellipsoidal particles are dispersed in a nematic liquid crystal solvent composed of rodlike micelles.
- Previous studies observed aggregation of ellipsoids with small aspect ratios into anisotropic structures, similar to spheres.
Purpose of the Study:
- To experimentally investigate the aggregation behavior of ellipsoidal particles in a nematic liquid crystal.
- To identify the critical aspect ratio at which particle aggregation transitions to a non-aggregated state.
- To provide a theoretical explanation for the observed aggregation transition.
Main Methods:
- Experimental dispersion of prolate ellipsoidal particles in a nematic liquid crystal solvent.
- Observation of particle behavior and structure formation over extended periods.
- Theoretical calculations to rationalize the observed aggregation and non-aggregation phenomena.
Main Results:
- Ellipsoids with small aspect ratios aggregate into anisotropic structures aligned with the director.
- A critical aspect ratio was identified, above which ellipsoids remain well-dispersed and do not aggregate.
- This transition from aggregated to non-aggregated states was observed for a given particle concentration and is not predicted by existing theories.
Conclusions:
- The aspect ratio of ellipsoidal particles plays a crucial role in their aggregation behavior within nematic liquid crystals.
- A transition from aggregation to dispersion occurs at a specific particle aspect ratio, a novel finding in particle self-assembly.
- Simple theoretical models were developed to explain this experimentally observed phenomenon, offering new insights into particle interactions in liquid crystals.
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