Association of nonionic polymer with hydrocarbon/fluorocarbon surfactant in aqueous solution

Abstract

The interaction between a nonionic polymer and a hydrocarbon or fluorocarbon surfactant has been investigated by means of surface tension, viscosity, electroconductivity, fluorescence probing, solubilization of a waterinsoluble dye, and electron spin resonance (ESR}. The systems studied consisted of polyvinylpyrrolidone (PVP) with lithium dodecyl sulfate (I,|DS) or lithium perfluoroo~ tane sulfonate (LiFOS). Surface tension measurements indicated that formation of PVP~surfactant complex is more favorable in the PVP-LiFOS system than in the PVP-LiDS system, and that the adsorbed amount of LiFOS is less than that of LIDS, although the CMCs of the surfactants are almost the same. In the PVP-LiFOS system, the relative viscosity and the solubilized amount of a water-insohible dye showed a maximum at a certain concentration of LiFOS in the region between two transitions observed in the surface tension, where also a change in the slope of the electroconductivity is observed. These results indicate that shielding of effective charge of the PVpoLiFOS complex causes a conformational change of PVP wrapped around the aggregate of LiFOS with an increase of free surfactant in the bulk phase. The conformational change can be correlated with microenviroumental properties of PVP-surfactant complexes. The microviscosity estimated with ESR indicated that the headgroups of LiFOS adsorbed on PVP are less tightly packed than those of LiFOS micelles, while an opposite result was obtained in the PVP-LiDS system. In particular, the marked high viscosity at a low concentration of LiFOS in the PVP-LiFOS system can probably be attributed to rigidity of the fluorocarbon chain of LiFOS.KEY WORDS: Lithium dodecyl sulfate, lithium perfluorooctane sulfonate, micvoenvironmental property, PVP-perfluorinated surfactant, solubilization of dye.

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

“…The concentration at which the maximum fluorescence wavelength starts to shift to the region of lower wavelength is lower for the co-polymer-LiFOS system than for the co-polymer-LiDS system. A similar behavior has been observed in PVP-LiDS and PVP-LiFOS systems (15). Accordingly, for the co-polymer-surfactant system, the co-polymer-surfactant aggregate is also a more favorable energy state for LiFOS than for LIDS.…”

Unusual location of the pyrene probe solubilized in the micellar solutions of tetraalkylammonium perfluorooctanoates

“…The change of I 1 /I 3 of pyrene has been applied to detect the micellization of traditional uorocarbon surfactants. [2][3][4][5] It is known that despite the immiscibility between hydrocarbon and uorocarbon groups, pyrene still shows a large solubility in the micelles of uorinated surfactants. 2,6 Based on the solubility of pyrene in water 7,8 and those data of partition coefficients of pyrene in hydrocarbon surfactants [9][10][11][12] and uorocarbon surfactants, 2,6,[11][12][13][14] it can be concluded that pyrene prefers to be solubilized in the uorocarbon micelles rather than stay in the aqueous phase, although its solubility in uorocarbon micelles is lower than in hydrocarbon micelles.…”

“…Their I 1 /I 3 ratio of pyrene is usually averaged to 1.5-1.7. 4,5,16,17 The following explanations can be summarized from many research papers: 3,[16][17][18] (i) the bulkiness and rigidity of uorocarbon chains, which induced smaller aggregation numbers 19 and thus relatively higher water penetration in micelles; (ii) the immiscibility between the hydrocarbon and uorocarbon species, which resulted in the less preferential partition of pyrene into uorocarbon micelles from an aqueous medium. As we all know, the uorescence spectra represent an average of the emission characteristics of the microenvironment among the distribution of the probes; 20 (iii) the location of solubilized pyrene was considered to be in the palisade layer of the micelles and closer to the micellar surface, where pyrene could more sufficiently contact with water.…”

An ESR Spin Probe Study of the Interaction between Poly(ethylene oxide) and Dodecyl Sulfate Surfactants with Different Monovalent Metal Counterions

“…Recently, some important studies about the microenvironment of nitroxide spin probes in micelles with polymer have been reported. [34][35][36][37][38][39][40] The ESR spin probe technique has several advantages. The sensitivity and selectivity of the spin probe to changes in its microenvironment provide the possibility to detect local differences of the polymer-surfactant systems.…”