Entropic Attraction and Repulsion in Binary Colloids Probed with a Line Optical Tweezer
- 24 May 1999
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 82 (21), 4352-4355
- https://doi.org/10.1103/physrevlett.82.4352
Abstract
The long-range entropic forces that arise between two micrometer-sized colloidal spheres in a fluid of much smaller colloidal spheres were directly measured using a line-scanned optical tweezer. This new technique allowed us to measure the functional form of the potential with sub- energy and spatial resolution. At the lowest small sphere concentrations, the potential was monotonically attractive, while at higher concentrations an oscillatory potential was observed, due to the liquid structure of the small spheres. Surprisingly, the large spheres came together only rarely at the higher concentrations, suggesting a new means for stabilizing suspensions using entropy alone.
Keywords
This publication has 31 references indexed in Scilit:
- Depletion forces in fluidsPhysical Review E, 1998
- Entropic forces in binary hard sphere mixtures: Theory and simulationThe Journal of Chemical Physics, 1997
- Effects of Particle Size and Polydispersity on the Depletion and Structural Forces in Colloidal DispersionsLangmuir, 1996
- Phase diagrams of nearly-hard-sphere binary colloidsPhysical Review E, 1995
- Multiple time scale derivation of the Fokker-Planck equation for two Brownian spheres suspended in a hard sphere fluidPhysica A: Statistical Mechanics and its Applications, 1995
- Phase Behaviour of Hard-Sphere MixturesEurophysics Letters, 1994
- Direct Observation of the Entropic Potential in a Binary SuspensionPhysical Review Letters, 1994
- Entropically Driven Surface Phase Separation in Binary Colloidal MixturesPhysical Review Letters, 1994
- Polymers at Interfaces and the Interactions in Colloidal DispersionsPure and Applied Chemistry, 1976
- Interaction between particles suspended in solutions of macromoleculesJournal of Polymer Science, 1958