Adsorption of surface active agents in a non-aqueous solvent

Couper, A.; Gladden, G. P.; Ingram, B. T.

doi:10.1039/dc9755900063

Cited by 41 publications

(22 citation statements)

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“…It has, however, been observed with non-ionic surfactants in formamide by Couper et al [18]. Moreover, results for experiments in progress have shown that the parameters of hexagonal and lamellar phases in the CTAB/formamide system are lower than those for water, and are relatively small, given the chain length of CTAB.…”

Section: Micellization In the Binary Ctab/formamide Systemsmentioning

confidence: 86%

“…mole -1 in water, and only-0.25 kJ. mole -1 in formamide [18]. Formamide thus behaves as a liquid that is highly structured round the hydrocarbon chains, and the low value of AH indicates that the exothermic chain interaction only just overcomes the endothermic destructuration of formamide.…”

Section: Micellization In the Binary Ctab/formamide Systemsmentioning

confidence: 94%

“…The free enthalpies per CH2 in formamide and water are also quite different (1.5 kJ. mo1-1 for formamide [18] and -2.9 kJ. mo1-1 for water).…”

Section: Micellization In the Binary Ctab/formamide Systemsmentioning

confidence: 95%

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Formamide, a water substitute XIV (1) waterless microemulsions 8. Structural analysis by X-ray scattering of CTAB aggregates in formamide and in the microemulsion system (formamide, CTAB, isooctane, 1-butanol)

Auvray

Petipas

Anthore

et al. 1987

Colloid & Polymer Sci

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X-ray scattering was used to analyse the structures of aggregates of CTAB in various formamide-containing media.Firstly, CTAB micelles were detected in formamide solutions. A spherical micelle model was proposed; at values close to the CMC, smaller micelles were observed in formamide than in water.Secondly, the structure of microemulsions in the isooctane-rich zone of the system (formamide/CTAB = 2, isooctane, 1-butanol) was studied by X-ray scattering. The structure was found to be quite different in this zone from that normally observed in aqueous microemulsions. Structures compatible with small filaments of formamide were detected. The results were related to previous measurements of electrical conductivity.

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Section: Micellization In the Binary Ctab/formamide Systemsmentioning

confidence: 86%

Section: Micellization In the Binary Ctab/formamide Systemsmentioning

confidence: 94%

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Formamide, a water substitute XIV (1) waterless microemulsions 8. Structural analysis by X-ray scattering of CTAB aggregates in formamide and in the microemulsion system (formamide, CTAB, isooctane, 1-butanol)

Auvray

Petipas

Anthore

et al. 1987

Colloid & Polymer Sci

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“…[f] From references [15,16], the data corresponding to the C 16 E 8 surfactant was obtained at 40 8C.…”

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confidence: 99%

Micelles in Ionic Liquids: Aggregation Behavior of Alkyl Poly(ethyleneglycol)‐ethers in 1‐Butyl‐3‐methyl‐imidazolium Type Ionic Liquids

Patrascu¹,

Gauffre²,

Nallet³

et al. 2006

ChemPhysChem

181

186

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Ionic liquids (ILs) are a new class of organic solvents that are stable over a large range of temperatures and have negligible vapor pressures.[1] Owing to their molecular structure, associating a cation and an anion, their physicochemical properties can be easily modulated by changing one of the ions. Ionic liquids are now widely used in organic synthesis and chemical separations due to their high solvation ability and their tuneable nature. [2,3] Almost unexplored, surfactant organization in ILs could open new research directions towards micellar catalysis into IL media, solvation enhancement for apolar entities and lyotropic properties. Indeed, surfactant organization occurs in some nonaqueous solvents [4,5] and is largely used in aqueous systems for drug vectorization, catalysis, gelification and other applications.[5] Recently, microemulsions have been obtained in IL-oil mixtures [6] and only premicellar aggregation has been detected in pure ILs. [7,8] However, no clear demonstration of the existence of a micellar phase in ILs has been reported yet.Here, we describe the behavior of a series of pure alkyl poly-(oxyethyleneglycol) ethers in 1-butyl-3-methyl-imidazolium (bmim) ILs with various counter ions [BF 4 À , PF 6 À and Tf 2 N À , that is, bis(trifluoromethylsulfonyl)amide; Figure 1]. The choice of nonionic surfactants, denoted C n E m (n = 12-16; m = 4-8), was justified to avoid the exchange of counter ions with the solvent. For high concentrations of surfactant (ca. 1 mol L À1 ), the mixtures C n E m /bmimBF 4 were generally solid at room temperature with a cloud point at high temperature (see Supporting Information). Herein, all experiments were performed at 25 8C with concentrations lower than 1 mol L À1, at which the mixtures were all limpid and homogeneous.Surface tension measurements were performed to probe the aggregation behavior of the surfactants in bmimBF 4 . For all the selected surfactants, the surface tension of the C n E m /bmimBF 4 solutions decreased when the surfactant concentration increased (Figure 2). This indicated their adsorption at the air/solution interface. The Szyszowski-Langmuir adsorption equation [9] fitted well this decrease, leading to an estimation of the area per molecule of the surfactant at the air/bmimBF 4 interface, that occurred to be comparable or lower than the ones found at the air/water interface (Table 1). Those differences between bmimBF 4 and water may be related to a change in the organization and/or solvation state of the adsorbed surfactants. In bmimBF 4 like in water, the molecular area of the surfactant decreased with increasing alkyl chain length or decreasing number of oxyethylene groups.This initial decrease of the surface tension is followed by an abrupt change in the slope of the surface tension versus C (Figure 3; semi-log plot). After this breaking point, the surface tension of the solutions remains more or less constant. Such a behavior suggested the formation of micelles within the ILs, where the break point corresponds to a critical micelle...

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“…[f] From (Couper et al, 1975;Jonstromer et al, 1990), the data corresponding to the C 16 E 8 surfactant was obtained at 40 °C.…”

Section: Surface Tension Measurementsmentioning

confidence: 99%

Aggregates in Ionic Liquids and Applications Thereof

Marty¹,

Viguerie²

2011

Ionic Liquids: Theory, Properties, New Approaches

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Adsorption of surface active agents in a non-aqueous solvent

Cited by 41 publications

References 0 publications

Formamide, a water substitute XIV (1) waterless microemulsions 8. Structural analysis by X-ray scattering of CTAB aggregates in formamide and in the microemulsion system (formamide, CTAB, isooctane, 1-butanol)

Formamide, a water substitute XIV (1) waterless microemulsions 8. Structural analysis by X-ray scattering of CTAB aggregates in formamide and in the microemulsion system (formamide, CTAB, isooctane, 1-butanol)

Micelles in Ionic Liquids: Aggregation Behavior of Alkyl Poly(ethyleneglycol)‐ethers in 1‐Butyl‐3‐methyl‐imidazolium Type Ionic Liquids

Aggregates in Ionic Liquids and Applications Thereof

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