Intermolecular association and supramolecular structures of PNVF–LiPFN and PVP–LiPFN complexes in the aqueous phase

Abstract

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.

Controlling the aggregation of sodium dodecylsulphate in aqueous poly(ethylene glycol) solutions

“…Such structure (bead-necklace model) formation in case of polymer surfactant systems has also been reported by others. 38,43,44 The values of the tted parameters are listed in Table 3. It is noteworthy that the formation of fractal structures is observed neither in case of SDS in D 2 O, nor in SDS in PEG-6000.…”

Direct experimental observation of mesoscopic fluorous domains in fluorinated room temperature ionic liquids

“…The peak volume of each cross-peak has been corrected by considering the contribution of the number of spins. The cross-peak intensity arising from N I equivalent spins I ( 1 H) and N S equivalent spin S ( 19 F) is proportional to the ratio of N I N S /(N I + N S ); 73 therefore, for semi-quantitative comparison, the original peak volume has been corrected by dividing the original integral by the value N I N S /(N I + N S ). For all the experiments, the temperature was set and controlled at 300 K. The spectra were processed with Topspin software (Bruker, version 3.5) The HOESY build-up curve were drawn plotting the normalized integral of the heteronuclear cross peak versus the mixing time (τ).…”

Solubilization of organics I: 1H NMR chemical shift perturbations, diffusometry, and NOESY indicate biphenyls internalize in micelles formed by cetyltrimethylammonium bromide

“…Intermolecular NOEs were analyzed semiquantitatively using reference distance method . The reference proton pair and the reference distance used in the computation of internuclear distances are H b ‐H c and 2.45 Å, respectively.…”