FT-IR investigation of the N-methylurea state in AOT reversed micelles

The state of N-methylurea (NMU) confined within the hydrophilic core of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reversed micelles (radius 1.5-1.8 nm) has been investigated by Fourier transform infrared spectroscopy. The analysis of the spectral features leads to the hypothesis that NMU is encapsulated in the micellar core as small-sized molecular clusters. As a consequence of their small size and of NMU-AOT head group interactions, these clusters display marked departures from the H-bonded structure of the pure solid NMU even at the higher NMU to AOT molar ratio. The stretching modes of NMU CO, AOT CO and sulfonate groups indicate unambiguously specific NMU-AOT head group interactions.