STATE OF SOLUTION OF AEROSOL OT IN NONAQUEOUS SOLVENTS

The state of solution of Aerosol OT (di-2-ethylhexyl sodium sulfosuccinate) was investigated in various nonaqueous solvents with the use of ultracentrifugation, light scattering, and viscometric techniques. Solvents included n-hydrocarbons, benzene, toluene, carbon tetrachloride, ethylene dibromide, t-amyl alcohol, and methanol. A brief study was also made of Aerosol TR (di tridecyl sodium sulfosuccinate) in n-dodecane. Micelles were found in all solvents except methanol, varying in size with solvent character. The Aerosol OT had a minimum micellar weight of 2500 in t-amyl alcohol. Maximum micellar weight (12,900) was found in n-hexadecane, corresponding to a micelle containing 29 molecules. Aerosol TR micelles in n-dodecane also appeared to contain 29 molecules (molecular weight = 17,000). The Aerosol OT micelles appeared essentially monodisperse and were generally slightly asymmetric in shape. The micellar weight in n-nonane did not change greatly between 25°C. (12,000) and 75° C (10,000). Differences in shape and size of micelles resulted from the presence of very minor amounts of an impurity in the original Aerosol OT. The micellar weight appeared to relate more directly to the molal volume of the solvent than to the solubility parameter. © 1969.