Selection of Surfactants as Emulsifying Agents

Correlations between the chemical structure of surface-active agents and their emulsifying power are complicated by the fact that both phases, oil and water, are of variable composition. This is in contrast to such phenomena as foaming or wetting, where one phase (the air) is more or less constant and some specific correlations can be made between structure and activity. Moreover, the concentration at which the emulsifying agent is used determines not only its emulsifying power, but even the type of emulsion (O/W or W/O) formed. As a result of this 

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Surfactants are widely used for a variety of reasons, including surface wetting agents, detergents, emulsifiers, lubricants, gasoline additives, and enhanced oil-recovery agents. The type of surfactants selected for a particular application often depends on the chemical and physical properties required and on economics or other considerations such as environmental concerns. To meet these requirements, a typical surfactant formulation may contain blends of a variety of commercial products, which could include ionic and nonionic ethoxylated surfactants, alkylsulfonates, and alkylaryl-sulfonates, and petroleum sulfonates. 

Perfluorochemical oxygen earners are not soluble in water. Therefore, perfluori-nated chemicals cannot be administered in the pure form but have to be converted to an aqueous emulsion. A surfactant, selected for its effectiveness and biochemical compatibility, serves as an emulsifier. Osmolarity and oncotic pressures are adjusted by adding electrolytes and oncotic agents, such as hydroxyethyl starch. Nutrients, thrombolytic agents, therapeutic agents, and other additives may be included in the emulsion, depending on the particular clinical application of the emulsion. 

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