Aqueous Solution Properties of Disulfide-Linked Fluorinated Gemini and Cleaved Monomeric Thiol Surfactants

Abstract

We prepared a fluorinated gemini surfactant containing a disulfide bond in its spacer chain, [C₈F₁₇ (CH₂)₃N(CH₃)₂CH₂CH₂SSCH₂CH₂N(CH₃)₂(CH₂)₃C₈F₁₇]2Cl, and its analogue with a hexamethylene spacer. Monomeric thiol surfactant, [C₈F₁₇(CH₂)₃N(CH₃)₂CH₂CH₂SH]Cl, was readily produced by the cleavage of the gemini surfactant using dithiothreitol in water. The critical micelle concentration was determined using surface tension, conductivity, and fluorescence probe methods. The critical micelle concentration of the monomeric surfactant was significantly larger than that of the gemini surfactant. The surface tension of aqueous solution for the cleaved monomeric thiol surfactant returned gradually to the original value through the formation of the disulfide bond via air oxidation.