THE INTERACTION BETWEEN DODECYL BETAINE A ND POLYVINYLPYRROLIDONE

The association and standard free energy of formation of the complex b etween dodecyl betaine(C12BE) and polyvinylpyrrolidone (PVP) in aqueou s solution have been investigated by using C-13 NMR, ESR and surface t ension measurement on the air/water interface. It is found that the ba sic structure of the complex is a micelle-like aggregate, the C12BE mo lecules were assembled on the methine(alpha), methylene(beta) carbon i n the backbone, and the methylene carbon attached to the nitrogen of P VP molecules, and shielding hydrocarbon groups on the surface of the m icelle from contact with water. Our results also confirm that the mice llization process in the presence of PVP occurs at a-lower concentrati on than that at the critical micelle concentration. The effectiveness of PVP in lowering the free energy of formation of the surfactant aggr egates in aqueous solutions increases with the increasing concentratio ns of PVP. The interfacial viscosity of the aggregates of PVP-C12BE is higher than that of C12BE ones.