The interaction of poly(N-vinylformamide) (PNVF) with anionic surfactant, sodium dodecyl sulfate (SDS), has been studied by pyrene fluorescence and two-dimensional nuclear Overhauser effect spectroscopy (2D NOESY). With use of pyrene as the probe, from low to high concentration of SDS, the pyrene I 1 /I 3 plot exhibits three stages of association of PNVF with SDS. The I 1 /I 3 plot vs [SDS] shows a well-defined plateau (I 1 /I 3 ) 1.47) at SDS concentrations ranging between 3 and 10 mM, indicating that in this range of SDS concentrations the sizes of polymer-bound SDS aggregates are approximately identical. The ambiguity in determining the critical aggregation concentration (cac) of SDS from the I 1 /I 3 plot vs [SDS], which resembles the typical profile of surface tension vs surfactant concentration, has been clarified by the 2D NOESY experiment. Also, just beyond the cac ([SDS] ) 3 mM), definite proof of formation of the PNVF-SDS complex bound on the polymer chain is provided by the 2D NOESY experiments. On the basis of the inter-and intramolecular cross-relaxation between the protons of PNVF and SDS, the microstructure of PNVF-induced SDS aggregates is proposed. Moreover, the association behavior of PNVF with SDS is compared to that of the poly(vinylpyrrolidone) (PVP)/SDS and poly(ethylene oxide) (PEO)/SDS systems.

A new polymer-surfactant system, the poly(N-vinylformamide) (PNVF)-lithium perfluorononanoate (LiPFN) system, has been studied by a combination of the surface tension method and twodimensional 1 H-19 F heteronuclear Overhauser effect NMR spectroscopy (2D 1 H-19 F HOESY). Using the surface tension method, we found that the critical aggregation concentration (cac) of LiPFN in the presence of PNVF is ca. 2 mM. In addition, the association behavior between LiPFN and PNVF is similar to that between poly(vinylpyrrolidone) (PVP) and LiPFN. The supramolecular structure of the PNVF-LiPFN complex in the aqueous phase is revealed by means of the 2D 1 H-19 F HOESY experiment. On the basis of the intermolecular cross-relaxation between the PNVF protons and the LiPFN fluorines, we could conclude that the PNVF chain do penetrate into the LiPFN aggregate. The semi-quantitative analysis of the internuclear distance indicates that the PNVF chain is not located at the center core of the LiPFN aggregate, but the PNVF chain thread itself through the surface shell of the LiPFN aggregate instead. PNVF protons are nearest to the fluorines next to the carboxyl group, suggesting that the interaction between PNVF and LiPFN is mainly due to the dipole-ionic attraction. Moreover, we have reinvestigated the supramolecular structure of PVP-LiPFN complex and have found that the PVP chain also penetrates into the LiPFN aggregate. In contrast with the PNVF-LiPFN complex, the PVP chain in the PVP-LiPFN complex is rather close to the middle part of the LiPFN molecules which constitute the polymer-bound aggregate. This indicates that the formation of PVP-LiPFN complex involves more or less fluorophilic interactions.