Nanoparticle Halos: A New Colloid Stabilization Mechanism

A new mechanism for regulating the stability of colloidal particles has been discovered. Negligibly charged colloidal microspheres, which flocculate when suspended alone in aqueous solution, undergo a remarkable stabilizing transition upon the addition of a critical volume fraction of highly charged...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2001-07, Vol.98 (16), p.8950-8954
Main Authors: Tohver, Valeria, Smay, James E., Braem, Alan, Braun, Paul V., Lewis, Jennifer A.
Format: Article
Language:English
Subjects:
Adsorption
Atoms & subatomic particles
Charged particles
Chemical engineering
Chemical suspensions
Colloids
Crystals
Flocculation
Fluids
Gels
Material concentration
Nanoparticles
Particle interactions
Physical Sciences
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Summary:A new mechanism for regulating the stability of colloidal particles has been discovered. Negligibly charged colloidal microspheres, which flocculate when suspended alone in aqueous solution, undergo a remarkable stabilizing transition upon the addition of a critical volume fraction of highly charged nanoparticle species. Zeta potential analysis revealed that these microspheres exhibited an effective charge buildup in the presence of such species. Scanning angle reflectometry measurements indicated, however, that these nanoparticle species did not adsorb on the microspheres under the experimental conditions of interest. It is therefore proposed that highly charged nanoparticles segregate to regions near negligibly charged microspheres because of their repulsive Coulombic interactions in solution. This type of nanoparticle haloing provides a previously unreported method for tailoring the behavior of complex fluids.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.151063098