Absorbent-Adsorbates: Large Amphiphilic Janus Microgels as Droplet Stabilizers
Bobby Haney1, Jörg G Werner2, David A Weitz
1Department of Chemical and Biomedical Engineering, FAMU-FSU Engineering, Tallahassee, Florida 32310, United States.
ACS Applied Materials & Interfaces
|June 30, 2020
Summary
Researchers fabricated Janus microgels (JM) with distinct hydrophilic and hydrophobic sides using microfluidics. These amphiphilic particles stabilize emulsions and offer stimuli-responsive behavior for potential applications in catalysis and fuel production.
Area of Science:
- Materials Science
- Colloid and Surface Chemistry
- Polymer Science
Background:
- Microgel particles are cross-linked polymer networks that swell in liquids, with expansion dependent on polymer-liquid interactions and cross-link density.
- Colloidal gels can stabilize emulsions by adsorbing at the interface of immiscible fluids.
- Enhancing adsorption of hydrophilic gel particles requires introducing hydrophobicity, leading to the need for amphiphilic Janus microgels.
Purpose of the Study:
- To fabricate amphiphilic Janus microgels (JM) with spatially distinct lipophilic and hydrophilic sides.
- To utilize these JMs as emulsion stabilizers with tunable properties.
- To demonstrate stimuli-responsive behavior in emulsions stabilized by JMs.
Main Methods:
- Fabrication of Janus microgels using microfluidic drop making with two immiscible monomer solutions (poly(ethylene glycol) diacrylate/poly(propylene glycol) diacrylate).
- Formation of Janus droplets in a flow-focusing junction intersected by a third immiscible fluid.
- Cross-linking of individual droplets via UV irradiation to form monodispersed microgel particles.
Main Results:
- Successfully synthesized poly(ethylene glycol) diacrylate/poly(propylene glycol) diacrylate Janus microgels with opposing hydrophilic and hydrophobic polymer matrices.
- Demonstrated amphiphilic emulsion stabilization, with JMs adsorbing to the oil-water interface and absorbing respective solvents.
- Achieved stimuli-responsive droplet behavior, with a sudden increase in droplet diameter around 60 °C due to thermal-responsive hydrogel formulation.
Conclusions:
- Janus microgels provide an effective amphiphilic emulsion stabilizer by combining distinct polymer gel networks.
- The developed microgels exhibit tunable, stimuli-responsive properties, particularly thermal responsiveness.
- These absorbent particles hold promise for applications in biocatalysis, fuel production, and oil transportation.
