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09:26
Synthesis and Characterization of Supramolecular Colloids
Published on: April 22, 2016
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Non-additivity of pair interactions in charged colloids
Samuel D Finlayson1, Paul Bartlett1
1School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.
The Journal of Chemical Physics
|July 25, 2016
Summary
The Derjaguin-Landau-Verwey-Overbeek theory predicts Yukawa interactions for charged colloids. Experiments show cross-interactions deviate from predictions, depending on screening length and particle size ratio.
Area of Science:
- Colloid science
- Soft matter physics
- Physical chemistry
Background:
- Classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory accurately describes interactions between charged colloids using Yukawa potentials.
- DLVO theory assumes interactions are additive, meaning cross-interactions can be predicted from like-interactions.
Purpose of the Study:
- To experimentally investigate the effective forces between like-charged colloidal particles in a binary mixture.
- To determine if the cross-interaction potential between different species of charged colloids aligns with DLVO predictions.
Main Methods:
- Utilizing blinking optical tweezers to precisely measure inter-particle forces.
- Analyzing the forces in a binary mixture of charged colloidal particles with varying size ratios.
Main Results:
- Measured forces are consistent with a Yukawa pair potential.
- The (12) cross-interaction between different particle species is not the geometric mean of (11) and (22) like-interactions, deviating from DLVO predictions.
- This deviation is dependent on the electrostatic screening length and particle size ratio, with observed cross-interactions being weaker than predicted.
Conclusions:
- The non-additivity of cross-interactions in charged colloidal mixtures is experimentally confirmed.
- A negative non-additivity parameter was observed, increasing with greater size asymmetry between particle species.
- Classical DLVO theory requires refinement to accurately model non-additive interactions in complex colloidal systems.
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