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Stable in Bulk and Aggregating at the Interface: Comparing Core-Shell Nanoparticles in Suspension and at Fluid
Siddarth A Vasudevan1, Astrid Rauh2,3, Lorenzo Barbera1
1Laboratory for Interfaces, Soft Matter and Assembly, Department of Materials, ETH Zürich , Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland.
Langmuir : the ACS Journal of Surfaces and Colloids
|July 29, 2017
Summary
Sterically stabilized nanoparticles show excellent stability in bulk suspensions but aggregate at oil-water interfaces due to shell deformation and capillary forces, revealing distinct behaviors under confinement.
Area of Science:
- Colloid and Surface Science
- Materials Science
Background:
- Colloidal particles are crucial for assembling materials in bulk suspensions and at fluid interfaces.
- Optimizing particle interactions for bulk assembly does not guarantee similar behavior at interfaces.
Purpose of the Study:
- To compare the behavior of model composite nanoparticles (silica core with hydrogel shell) in bulk aqueous suspensions versus at oil-water interfaces.
- To investigate how interfacial confinement affects the properties of sterically stabilized nanoparticles.
Main Methods:
- Confocal differential dynamic microscopy for bulk suspension analysis.
- Interfacial studies using complementary experimental approaches.
Main Results:
- Particles exhibited excellent colloidal stability and no aggregation in bulk suspensions.
- Hydrogel shells deformed at the oil-water interface, inducing attractive capillary interactions.
- Aggregation occurred at low surface coverage, with a structural transition upon compression.
Conclusions:
- Sterically stabilized nanoparticles display significantly different behaviors in bulk versus at interfaces.
- Interfacial confinement can lead to unexpected aggregation due to capillary forces and shell deformation.
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