Aggregation Behavior of Disulfide Linked Gemini Surfactants Compared to that of Double Tailed Surfactants

Disulfide linked gemini surfactant having a long spacer chain, [C10H21N(CH3)(2)(CH2)(11)SS(CH2)(11)N (CH3)(2)C10H21](2)Br (2C(10)11SS), was prepared by the hydrolysis and oxidation process of thioester group for [C10H21N(CH3)(2)(CH2)(11)SCOCH3]Br. The critical vesicle concentrations of double tailed surfactants such as dialkyldimethylammonium bromide were observed by the conductivity and light scattering methods. The disulfide bonds of gemini surfactant, [C12H25N(CH3)(2)CH2CH2SSCH2CH2N(CH3)(2)C12H25]2Br (2C(12)SS), were rapidly cleaved by the addition of water-soluble dithiothreitol. However, it took long time to cleave the disulfide bonds of so-called double tailed surfactants 2C(10)11SS due to vesicle formation. The dynamic light scattering method showed that the diameters of 2C(12)SS micelles were increased with the cleavage of disulfide bonds, whereas those of 2C(10)11SS aggregates remained almost constant at 17.6 +/- 1.3 nm in similar size with dialkyldimethylammonium bromide vesicles. The time course of disulfide cleavage was examined by the conductivity and HPLC analysis. The produced thiol surfactants were returned to their original gemini surfactants by the addition of H2O2.