Stabilization of water-in-water pickering emulsions by charged particles

Abstract

The stability of Pickering emulsions depends on interfacial coverage of the emulsion droplets. Since, the interfacial thickness of water-water interface is very high, particles of comparable thickness can stabilize water-in-water (w/w) emulsions. To achieve this, mixture of oppositely charged particles are used, which are known to form large neutral aggregates and can be effective stabilizers for such emulsions. The w/w emulsions were formed by mixing PEO and dextran at different composition and the effect of surface charge of the particles on the kinetic stability of dextran-in-poly(ethylene oxide) (PEO) (D/P) emulsions was investigated. The phase preference of charged particles was also determined. The emulsions were visualized by confocal laser scanning microscope and characterized by drop size distribution and time evolution of drop size. It was found that negatively charged particles and mixture of oppositely charged particles (OCP) preferred the PEO phase and stabilize D/P emulsions. However, only the OCP were more effective stabilizers as they achieved complete interfacial coverage.

Graphical Abstract

Keywords:

• Aqueous two-phase systems (ATPS)
• PEO–dextran emulsion
• particle surface charge
• kinetic stability
• interfacial coverage
• coalescence

Conflict of interest

The authors declare no competing financial interest.

Additional information

Funding

This work was supported by the Science and Engineering Research Board under the Department of Science and Technology (DST), India under Grant CRG/2020/000847.