Hypothesis: Water-in-water emulsions can be stabilized by colloidal particles that spontaneously adsorb at the interface. Different types of particles have been shown to exhibited different impact on the microstructure and stability. The combination of two different types of particles is expected to show a synergistic effect on the emulsion stability.
Experiments: Synthetic bis-hydrophilic microgels (BIS) and protein microgels (PRO) were studied in emulsions formed by mixing polyethylene oxide (PEO) and Dextran (DEX) as well as in the individual phases. The arrangement of particles at the interface was monitored using confocal laser scanning microscopy and the effect on the microstructure and stability of the emulsions was evaluated during aging.
Findings: The adsorption and arrangement of particles at the interface depended mainly on their affinity for each phase. Formation of a mixed layer significantly increased the stability of the emulsions compared to emulsions with the individual microgels. BIS and PRO co-aggregated in the PEO phase, which affects their arrangement at the interface and the emulsion stability. In some cases, added BIS spontaneously fully replaced PRO that was adsorbed at the interface.
Keywords: All-aqueous two-phase system; Bis-hydrophilic microgels; Emulsion stability; Pickering effect; Protein microgels; Water-in-Water emulsion.
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