Micellar Properties of Two-Headed Anionic Surfactants

헤드그룹이 두 개인 음이온성 계면활성제의 미셀특성

Density, viscosity, conductance, dye solubility and carbon-13 nmr studies were performed in aqueous solution of three disodium 4-n-alkyl-3-sulfonatosuccinate anionic surfactant at $20^{\circ}C$. The cmc values were 0.14 mol/l for the disodium-4-n-octyl-3-sulfonatosuccinate($R_{8)S$), 0.041mol/l for the disodium-4-n-decyl-3-sulfonatosuccinate($R_{10}S$), and 0.018mol/l for the disodium-n-dodecyl-3-sulfonatosuccinate <$R_{12}S$). The aggregation numbers determined viscometrically and conductimetrically were 28 for $R_{8}S$, 48 for $R_{10}S$, and 67 for $R_{12}S$. The volume changes upon micellization were $8.9cm^{3}/mol$ for $R_{8}S$, $9.5cm^{3}/mol$ for $R_{10}S$, and $10.1cm^{3}/mol$ for $R_{12}S$. Binding constants for the dye pada to the micelles and the fractions of unbound counter-ion were also obtained. The two polar heads with their carbon linkage were likely in an aqueous environment in the $R_{8}S$ micelles with the micelles themselves being spherical.