C-13 NMR and ESR studies on the association between sodium 3-dodecyl ether-2-hydroxypropyl-1-sulfonate and polyvinylpyrrolidone

The surfactant, sodium 3-dodecyl ether-2-hydroxypropyl-1-sulfonate(SDEHS) w as synthesized. The association and standard free energy of formation of th e complex between sodium 3-dodecyl ether-2-hydroxypropyl-1-sulfonate(SDEHS) and polyvinylpyrrolidone(PVP) in an aqueous solution have been investigate d using C-13 NMR, ESR spectra, and surface tension measurements at the air/ water interface. C-13 NMR and ESR spectra all indicate that the basic struc ture of the complex is a micelle-like aggregate, the SDEHS molecules assemb ling on the methylidyne(alpha), the methylene(beta) carbon in the backbone, and the methylene carbon attached to the nitrogen of PVP molecules, and sh ield hydrocarbon groups on the surface of the micelle from contacting with water. The measurement results of surface tensions show that the amount of surfactant bound to the polymer are linear function of the polymer concentr ations(phi, wt%) ie., (c(2)-c(1))=2 phi, and the micellization in the prese nce of PVP occurs at a Iowa concentration than the critical micelle concent ration of SDEHS. The effectiveness of PVP in lowering the free energy of fo rmation of the surfactant aggregates in aqueous solutions increases with th e concentrations of PVP.