Investigation of influence of nonionic additives on structural changes of water droplets encapsulated in AOT reverse micelles by instrumental methods

The microstructure of sodium bis(2-ethylhexyl) sulfosuccinate reverse micelles was investigated using infrared, nuclear magnetic resonance and ultraviolet–visible spectroscopic methods, also by water-in-oil microemulsion chromatography. The influence of structure-making and structure-breaking nonionic additives on the microenvironment in reverse micelles was studied. The values of chemical shift in the presence of chaotropic urea are different than their values in case of kosmotropic glucose additives according to proton magnetic resonance spectroscopic data. Urea promotes an increasing of free water fraction in the water pockets of the reverse microemulsions, but glucose supports formation of the trapped water on the basis of deconvolution of the OH stretching vibrational absorption spectra in the region of 3000–3800 cm−1 into three subpeaks with a Monte Carlo method. The different influence of kosmotropic and chaotropic nonionic additives on both binding constant Kb of o-nitroaniline to the micelles of AOT and retention of the model compounds were also revealed by UV–visible spectroscopic and water-in-oil microemulsion liquid chromatography methods respectively.