Particles Trapped at the
Droplet Interface in Water-in-Water
Emulsions
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Abstract
Water-in-water emulsions were formed by mixing incompatible
aqueous
solutions of dextran and poly(ethylene oxide) (PEO) in the presence
of latex or protein particles. It was found that particles with a
radius as small as 0.1 μm become trapped at the interface between
the PEO- and dextran-rich phases with interfacial tensions down to
10<sup>–6</sup> N/m. The particles were visualized at the interface
of the emulsion droplets using confocal laser scanning microscopy
(CLSM) allowing determination of the contact angle. Various degrees
of coverage with particles could be observed. On densely covered droplets,
the particles had a hexagonal crystalline order. At intermediate coverage,
transient clustering of the particles was observed. The diffusion
coefficient of the particles at the interface was determined using
multiparticle tracking. Fusion of droplets was observed in all cases
leading eventually to macroscopic phase separation
