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Double Emulsion Generation Using a Polydimethylsiloxane PDMS Co-axial Flow Focus Device
Published on: December 25, 2015
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Double emulsions and colloidosomes-in-colloidosomes using silica-based Pickering emulsifiers.
Mark Williams1, Steven P Armes, Pierre Verstraete
1Department of Chemistry, University of Sheffield , Brook Hill, Sheffield, South Yorkshire S3 7HF, U.K.
Langmuir : the ACS Journal of Surfaces and Colloids
|February 25, 2014
Summary
This study introduces hybrid Pickering emulsifiers made from poly(ethylene imine) and fumed silica. These hybrid particles enable the creation of stable oil-in-water, water-in-oil, and water-in-oil-in-water double emulsions with tunable droplet sizes.
Area of Science:
- Colloid and Surface Science
- Materials Science
- Emulsion Technology
Background:
- Pickering emulsions offer an alternative to traditional emulsifiers.
- Hybrid particles combining polymers and inorganic materials can enhance emulsion stability and functionality.
Purpose of the Study:
- To develop novel hybrid Pickering emulsifiers using poly(ethylene imine) and fumed silica.
- To investigate the formation of oil-in-water (o/w), water-in-oil (w/o), and water-in-oil-in-water (w/o/w) double emulsions.
- To control droplet size and explore potential applications in encapsulation.
Main Methods:
- Adsorption of poly(ethylene imine) (PEI) onto fumed silica particles at pH 10.
- Systematic variation of the PEI/silica mass ratio to modify particle surface properties.
- Homogenization of fragrance oil and aqueous dispersions to form Pickering emulsions.
- Characterization of emulsion types (o/w, w/o, w/o/w) and droplet sizes.
- Fluorescence microscopy for droplet encapsulation studies.
- Epoxy-amine cross-linking for enhanced stability.
Main Results:
- Stable o/w Pickering emulsions formed with increasing PEI/silica ratio.
- Phase inversion to stable w/o Pickering emulsions at higher PEI/silica ratios.
- Successful preparation of stable w/o/w double emulsions with tunable oil volume fractions (5-42%).
- Control over oil droplet diameter (20-160 μm) by adjusting homogenization parameters.
- Demonstrated encapsulation of single or multiple droplets within larger oil droplets.
- Potential for creating cross-linked colloidosomes-in-colloidosomes with improved payload retention.
Conclusions:
- Hybrid PEI/silica particles act as effective Pickering emulsifiers for creating complex emulsion systems.
- The PEI/silica mass ratio is a key parameter for controlling emulsion type and stability.
- This method allows for the facile production of w/o/w double emulsions with tunable droplet sizes and encapsulation capabilities.
- The developed system shows promise for advanced encapsulation applications, potentially through cross-linking to form novel colloidosomes.
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