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Synthesis and Characterization of Supramolecular Colloids
Published on: April 22, 2016
Correlation between colloidal stability and surfactant adsorption/association phenomena studied by light scattering.
Alessio Zaccone1, Hua Wu, Marco Lattuada
1Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland.
The Journal of Physical Chemistry. B
|January 31, 2008
Summary
Colloidal system stability dramatically increases with potassium stearate (KS) surfactant concentration up to surface saturation. Beyond saturation, stability decreases due to depletion forces from micelle formation, impacting particle aggregation kinetics.
Area of Science:
- Colloid and Surface Science
- Polymer Chemistry
- Materials Science
Background:
- Colloidal systems are crucial in various industrial applications.
- Understanding particle interactions and stability is key for controlling material properties.
- Nonsmooth colloidal particles present unique challenges in stability investigations.
Purpose of the Study:
- To determine the colloidal stability of styrene-acrylate copolymer particles with potassium stearate (KS).
- To investigate the effect of KS concentration on particle aggregation kinetics.
- To model the adsorption behavior of KS on particle surfaces.
Main Methods:
- Small-angle light scattering (SALS) to measure initial aggregation kinetics.
- Surface tension measurements to determine adsorption isotherms.
- Lorenz-Mie theory for fitting static light scattering spectra.
- Turbulent capillary experiments to assess stability under shear.
Main Results:
- Colloidal stability (Fuchs stability ratio, W) increases with KS concentration until surface saturation.
- Beyond saturation, W decreases due to attractive depletion forces from micelle formation.
- Adsorption isotherm follows a two-step Langmuir model, consistent with stability data.
- KS adsorption significantly increases particle diameter.
- Depletion forces are noncooperative with turbulent shear without screening electrolytes.
Conclusions:
- KS surfactant concentration critically influences styrene-acrylate copolymer particle stability.
- Surface saturation marks a transition point, beyond which depletion forces dominate.
- The study provides a model for understanding the stability of nonsmooth colloidal particles.
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