| Abstract
| - Using small-angle X-ray scattering (SAXS) and interfacial tension measurements, we show thatconcentrated solutions of dimethyldioctylhexylethoxymalonamide diluted in dodecane are organized inreverse aggregates that have many features in common with reverse micelles. The critical micellarconcentration is determined from interfacial tension measurements using the pendant-drop technique,and the aggregation number is given by fitting SAXS data on the absolute scale. The effect of the additionof n-octanol, a modifier widely used in liquid/liquid extraction, is studied by SAXS. It is shown that, forsmall amounts of alcohol, the modifier acts as a cosurfactant; it swells the reverse micelles by adsorbingonto the aggregates and increases the surface per extractant polar head. When n-octanol is added in largerquantities, a new microstructure appears, and the amount of octanol required for this transition dependson the amount of diamide in solution (for example, octanol concentration ≥ 1 M for 0.7 M diamide).Therefore, a hydrogen-bond network is present in solution, and the presence of areas of high electronicdensity separated by a distance varying from 15 to 20 Å is found to explain the scattering patterns.
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