FT-IR Investigation of the Urea State in AOT Reversed Micelles

✍ Scribed by G. Calvaruso; A. Minore; V.Turco Liveri

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 76 KB
• Volume: 243
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.2001.7878

✦ Synopsis

FT-IR spectra of the urea/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/CCl 4 system as a function of the urea-to-AOT molar ratio (R urea ) at a fixed AOT concentration ([AOT] = 0.1 mol • kg -1 ) have been recorded at 25 • C. The experimental data are consistent with the hypothesis that at low R urea values urea is dispersed as monomers among the hydrophilic core of AOT reversed micelles, whereas at R urea > 0.13 it is encapsulated as small molecular clusters. These clusters display some departures from the H-bonded structure of the pure solid urea attributable to their small size and to urea-AOT head group interactions. The stretching modes of AOT sulfonate groups are affected by the presence of urea, indicating specific urea-AOT head group interactions. On the other hand, analysis of the AOT CO stretching band provides evidence that these groups are not significantly involved in urea-AOT interactions.