Emulsion double

The most common types of emulsions consist of only two Hquids, water and an oil. An o/w emulsion consists of oil droplets dispersed in a continuous aqueous phase, and a w/o emulsion consists of water droplets dispersed in oil (Fig. 1). Occasionally inversion takes place an o/w emulsion changes into w/o emulsion and vice versa. More complex emulsions such as double emulsions are formed because the water droplets in a continuous oil phase themselves contain dispersed oil droplets (Fig. 2). Such oil-in-water-in-oil emulsions are noted as o/w/o. In the same manner a w/o/w emulsion may be formed, which finds use as a system for slow deHvery, extraction, etc (6,7). 

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Stroeve, P., and Varanasi, P. P., An experimental study of double emulsion drop breakup in uniform shear flow. J. Coll. Int. ScL 99,360-373 (1984). 

Ulbrecht, J. J., Stroeve, P., and Pradobh, P., Behavior of double emulsions in shear flows. Rheol. Acta 21, 593-597 (1982). 

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Han SS, Kim MK. An improved method for double-isotope and double-emulsion radioautography using epoxy resin sections. Stain Technol 1972 47 291-296. 

The preparation of a ferrofluid emulsions is quite similar to that described for double emulsions. The starting material is a ferrofluid oil made of small iron oxide grains (Fe203) of typical size equal to 10 nm, dispersed in oil in the presence of an oil-soluble surfactant. The preparation of ferrofluid oils was initially described in a US patent [169]. Once fabricated, the ferrofluid oil is emulsifled in a water phase containing a hydrophilic surfactant. The viscosity ratio between the dispersed and continuous phases is adjusted to lie in the range in which monodisperse fragmentation occurs (0.01-2). The emulsification leads to direct emulsions with a typical diameter around 200 nm and a very narrow size distribution, as can be observed in Fig. 1.33. 

S. Okushima, T. Nisisako, T. Torii, and T. Higuchi Controlled Production of Monodisperse Double Emulsions by Two-Step Droplet Breakup in Microfluidic Devices. Langmuir 20, 9905 (2004). 

C. Goubault, K. Pays, D. Olea, J. Bibette, V. Schmitt, and E. Leal-Calderon Shear Rupturing of Complex Fluids Application to the Preparation of Quasi-Monodisperse W/OAV Double Emulsions. Langmuir 17, 5184 (2001). 

K. Pays, J. Giermanska-Kahn, P. Pouligny, J. Bibette, and F. Leal-Calderon Double Emulsions A Tool for Probing Thin Film MetastabUity. Phys. Rev. Lett. 87,178304 (2001). 

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