Abstract: This investigation is related to solubilisation process of aqueous micellar solu- tion containing nonpolar m-xylene or moderately polar benzyl alcohol and surfac- tant sodium dodecyl sulfate (SDS) by high resolution proton nuclear magnetic resonance spectroscopy (~1H-NMR).
The examined results indicate that the long chain methylene in SDS shows a singlet signal for m-xylene/SDS/H_2O system,while it is split into an up-field signal and a down-field signal for benzyl alcohol/SDS/H_2O system. From the de- pendence of chemical shifts of SDS on solubilisate concentration, it is ascertained that at low solubilisate contents m-xylene or benzyl alcohol is solubilised by adsorption at the micelle-water “interface”. With further addition of m-xylene, it is solubilised and uniformly distributed along the hybrocarbon chain of surfactant. When mole fraction of m-xylene in surfactant is about 0.34, m-xylene goes predominantly the hydrocarbon chain of hte surfactant molecules. Whereas, benzyl alcohol solubilisation is probably localized in the palisade layer. It is orientated in such a manner ring is directed towarde the micellar interior. When a benzyl alcohol content approximates to 0.77 mole fraction, benzyl alcohol may go predominantly to the centre of the micellar interior core.
The above-mentioned results are also discussed theoretically in this paper.