STRUCTURE OF WATER-IN-OIL MICROEMULSIONS OF AOT BY INFRARED SPECTROSCOPY

The structure of water in water/AOT/n-heptane reverse micelles has been studied as a function of the [H2O]/[AOT] ratio (W) by using the absorption IR due to O−H stretching modes in the 3800–3000 cm−1 range. The results show that the IR spectra can be expressed as a sum of contributions from bound- and bulk-like water. The fraction of water in the two «regions» within the water pool was evaluated as a function of W. The «bound» water region seems to hold 3.5 water molecules (corresponding to 7 O−H oscillators) per AOT molecule and its formation is nearly complete at W>6.