Double Emulsions Stabilized by Macromolecular Surfactants

The stability of double emulsions can be improved by forming a polymeric film or macromolecular complex across the oil-water interfaces. Multiple emulsions are emulsions within emulsions, as the droplets of the dispersed phase themselves contain even smaller dispersed droplets. Monomeric surfactants have traditionally been used both at the inner interface and the outer interface. Ionic and non-ionic surfactants have been used for different applications, inaccordance with health restrictions. Crosslinking of the surfactant molecules may be induced by simultaneous activation of two neighbouring molecules with the net increase of the molecular weight of the polymer until a three-dimensional network is formed. The surfactant consisting of the longer ethylene oxide units attached to the backbone will best retain the NaCl within the inner phase. The use of synthetic well-designed and characterized polymeric surfactants was very helpful in reducing the leakage of addenda, improving shear resistance and obtaining double emulsions of smaller droplet sizes with excellent shelf-life and stability.