The interaction between co-polymer of vinylpyrrolidone and vinylacetate and anionic surfactants in aqueous solutions

The interaction of co-polymers of vinylpyrrolidone-vinylacetate with anionic surfactants, such as lithium dodecyl sulfate (LiDS), lithium perfluorooctane sulfonate (LiFOS) in aqueous solution, has been studied. When the content of vinylacetate in the co-polymers increases, reduction in the surface tension of co-polymers alone becomes significant. In mixtures of co-polymers and surfactants, co-polymer-LiFOS complexes are formed at lower surfactant concentration than that of co-polymer-LiDS. The micropolarity of the co-polymers-surfactant complexes depends on the composition of co-polymers and is higher for co-polymer-LiFOS than that for co-polymer-LiDS. Further, the solubilization behavior of α-(o-tolylazo-)-β-naphthylamine (Yellow OB) (Tokyo Kasei Co., Ltd., Tokyo, Japan) in the co-polymer-surfactant complexes is almost independent of the co-polymer composition, but different from the surfactants, where a very low solubilized amount of Yellow OB is observed for co-polymer-LiFOS.