lize oil-in-formamide emulsions (2,3). The first approach We examined the stability of emulsions of oil in several nonaquehas the drawback of necessitating the specific design and ous polar liquids using commercially available nonionic surfaccharacterization of a new surfactant for each combination of tants. Stable nonaqueous emulsions were only obtained with forliquids. In this work we therefore chose the second approach.
mamide and dimethylsulfoxide. Hydrogen bonding, and not polar-
A liquid capable of replacing water in an emulsion should ity, appears to be the important factor determining the emulsifying have a high polarity to make it immiscible with oils and to power of a solvent. Ostwald ripening plays a much more important make it a good solvent for the hydrophilic part of surfactant role in the stability of these nonaqueous emulsions than in the molecules. Furthermore, hydrogen bonding is expected to corresponding aqueous systems. This destabilizing process can be play a role in solvating both ionic and nonionic surfactants prevented, however, by addition to the oil phase of a small amount (1%) of an oil that has a very low solubility in the continuous and in the formation of a hydrogen-bonded network in the phase. Furthermore, a larger size of the surfactant molecule proliquid itself. The influence of these factors is investigated in tects emulsions against droplet coalescence. Thus, emulsions in this work by examining emulsion stability for a variety of formamide and dimethylsulfoxide did not show any breakdown polar liquids in combination with surfactants over a range when stabilized with a triblock copolymer of polyoxyethyleneof HLB numbers.