Molecular Self‐Aggregation of Tetradecylbenzene Sodium Sulfonate Isomers

Abstract

AbstractThis paper deals with the effect of the surfactant isomeric structure on self‐aggregation in aqueous solution. The relationship between the molecular structure of a series of tetradecylbenzene sulfonate isomers (with the benzene ring located at different positions along the alkyl chain) and surface tension was made clear. It is found that the critical micelle concentration increases and the surface tension at critical micellar concentration decreases as the benzene group moves toward the center of the alkyl chain. The structure of micelles was studied by 1H‐NMR relaxation, which indicates that the density of methylene protons in the surface layer of the micellar core decreases as the branching of the hydrophobic group increases. The spontaneous vesicle formation in aqueous solution was investigated by transmission electron microscopy. The results reveal that, as the benzene group moves toward the center of alkyl chain, the assembly structure changes from micelle to vesicle, then to lamellar bilayers, while the critical packing parameter increases.