FT-IR and nuclear overhauser enhancement study of the state of urea confined in AOT-reversed micelles

Abstract The system urea/sodium-bis(2-ethylhexyl)sulfosuccinate (AOT) dispersed in CCl 4 and benzene-d6 was investigated by viscosimetry, FT-IR and high-resolution 1 H NMR spectroscopy, as a function of urea/AOT molar ratio ( R urea ) at fixed AOT molal concentration (0.3467 mol kg −1 ) and as a function of AOT concentration at fixed R urea (0.5) at 25 °C. The experimental data are consistent with the hypothesis that urea is encapsulated as small-size hydrogen-bonded cluster in the hydrophilic micellar core of the AOT-reversed micelles and that this structure is maintained well above the volume fraction of the dispersed phase, where a percolative transition occurs. Intermolecular nuclear ov…