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The Preparation of Electrohydrodynamic Bridges from Polar Dielectric Liquids
Published on: September 30, 2014
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Making and breaking bridges in a Pickering emulsion.
David J French1, Phil Taylor2, Jeff Fowler3
1School of Physics & Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK.
Journal of Colloid and Interface Science
|December 10, 2014
Summary
Particle bridges in Pickering emulsions form under specific conditions and can be broken by adjusting shear or particle wettability. This study explores factors influencing particle bridging and its reversal.
Area of Science:
- Colloid and Surface Science
- Materials Science
Background:
- Pickering emulsions are stabilized by particles at the oil-water interface.
- Particle bridging occurs when interfacial area exceeds stabilization capacity, influenced by particle properties and shear.
- Understanding bridging is crucial for controlling emulsion stability and properties.
Purpose of the Study:
- To investigate the formation and breaking mechanisms of particle bridges in Pickering emulsions.
- To identify key parameters affecting particle bridging, including shear rate, particle volume fraction, and wettability.
- To provide direct evidence of droplet-particle interactions leading to bridging.
Main Methods:
- Development of a model oil-in-water Pickering emulsion system using fluorescent Stöber silica.
- Utilizing light scattering and microscopy to quantify the degree of emulsion bridging.
- Employing freeze fracture scanning electron microscopy for direct visualization of particle bridging.
- Systematic variation of particle volume fraction, wettability, and shear rate.
Main Results:
- Successfully created strongly aggregating Pickering emulsions by tuning parameters.
- Particle bridging requires particles with a slight preference for the continuous phase.
- Bridging increases with shear rate but decreases with particle volume fraction.
- Particle bridges were reversible through low shear or wettability modification.
Conclusions:
- Particle bridging in Pickering emulsions is controllable by manipulating shear and particle wettability.
- The findings offer insights into the fundamental mechanisms governing emulsion stability.
- This work provides a basis for designing and controlling Pickering emulsions for various applications.
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