The effect of electrolytes on the cloud point of ionic-nonionic surfactant solutions

Marszall, Leszek

doi:10.1016/0166-6622(87)80308-6

Cited by 39 publications

(9 citation statements)

References 37 publications

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“…The highly convoluted surface of Triton X-100 micelles has been demonstrated by SAXS. 11 This view is reasonable because (a) EO chain dehydration results in increased structural disorder 32,33 and (b) at increased electrolyte concentrations water cluster formation is favored and, therefore, relatively large "icebergs" of water may be associated with the micelles, which may extend to considerable distances from the micellar hard-sphere surface.…”

Section: Resultsmentioning

confidence: 99%

Electrolyte-Induced Structural Evolution of Triton X-100 Micelles

2000

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The long-time self-diffusion coefficients of Triton X-100 micelles have been determined as a function of surfactant and electrolyte concentrations using rotating disk electrode voltammetry in conjunction with ferrocene acting as an electroactive probe. Micellar diffusion conforms to the linear interaction theory and yields micellar hydrodynamic radii values and interaction parameters as a function of electrolyte concentration. The interaction parameters varied from 3.4 to 3.6 over the electrolyte concentration range 0.01−0.8 mol dm-3 KCl, which is consistent with excluded volume interactions and indicated the absence of significant micellar shape changes with the addition of electrolyte. Micellar hydrodynamic radii varied linearly with respect to [KCl] from 4.22 to 6.21 nm, indicating the progressive evolutionary growth of the oblate micelles due to increasing aggregation number and “hydration”. The semimajor to semiminor axial ratio (a/b) increased from 2.0 to 3.5, indicating evolution to a more asymmetric structure. Micellar molecular weights increased from 77 700 to 326 000 over the electrolyte concentration range studied, which is predominantly due to water entrapment at the periphery of the self-assembled structures. Intrinsic viscosities were found to decrease from 6.09 to 4.61 cm3 g-1, indicating a decrease in specific micellar volume, which may be attributed to ethylene oxide chain collapse due to dehydration. The decrease in micellar specific volume was found to correlate precisely with the electrolyte induced decrease of the cloud point.

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Section: Resultsmentioning

confidence: 99%

Electrolyte-Induced Structural Evolution of Triton X-100 Micelles

2000

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“…However, the presence of significant quantities of water entrapped by the micelles at elevated salt concentrations may be due to the roughness of the micellar surface leading to the physical entrapment of H 2 O that diffuses with the particle. This view is reasonable because (a) EO chain dehydration results in an increased structural disorder [115,116], and (b) at increased electrolyte concentrations water cluster formation is favoured. Therefore, relatively large "icebergs" of water may be associated with the micelles, which may extend to considerable distances from the micellar hard-sphere surface.…”

Section: Effect Of Electrolytesmentioning

confidence: 91%

Clouding behaviour in surfactant systems

Mukherjee

Padhan

Dash

et al. 2011

Advances in Colloid and Interface Science

166

109

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“…As this result seemed at first sight surprising, we thought it of interest to investigate further these micellar systems by focussing on the cloud point (CP) behavior of Triton X-100 with SDS and Cu(DS)2. A number of authors have recently shown that small additions of an ionic surfactant considerably increases the cloud point of a nonionic surfactant [5] or the mutual miscibility of an organic solvent and water [6]. The most straightforward interpretation of the dramatic CP increase is through the assumption of the solubilization of the surfactant ion by the nonionic micelle with, as a consequence, a repulsive force between micelles and therefore, a higher CP value.…”

Section: The Degree Of Dissociation Of Mixed Cationic/nonionic Rnicellesmentioning

confidence: 98%

“…For example, the conditions for the precipitation of polyelectrolytes by surfactants of opposite charges can be controlled by the use of mixed surfactants which defines a critical potential for complex formation between polyelectrolyte and micelle 0658 [4]. Another recent example is provided by the strong increase of the cloud point ofa nonionic surfactant [5], or simply of a dilute amphiphile induced by the addition of minute amounts of an ionic surfactant [6]. The electrostatic repulsion induced by the mixed micelle formation is responsible for the observed effects.…”

Section: Introductionmentioning

confidence: 99%

Counter ion condensation on mixed cationic/nonionic micellar systems: Bjerrum's electrostatic condition

Treiner

Mannebach

1990

Colloid & Polymer Sci

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Abstract:The association of counter-ions with mixedionic/nonionic micelles has been investigated in the case of dodecyl/tetradecyl/and hexadecyl-trimethylammonium bromide with two nonionic surfactants: dodecylpolyoxyethylene 23 and Triton X-100. The degree of association has been measured by potentiometry using a Bromide ion-selective electrode. Previous results with sodium and copper dodecylsulfate suggesting that in the nonionic-rich composition domain, bare mixed micelles are formed without associated counter-ions have been confirmed. These results are in agreement with the prediction of Bjerrum's condition for ion association. The effect of copper dodecylsulfate on the cloud point of Triton X-100 has also been determined as a means of investigating mixed micelles with multivalent counter-ions. The dramatic cloud point increase observed, even larger than with sodium dodecylsulfate, has been discussed as evidence of the solvation of divalent ions by ether groups, a factor which complicates the analysis of multivalent counterion condensation on mixed micelles.

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The effect of electrolytes on the cloud point of ionic-nonionic surfactant solutions

Cited by 39 publications

References 37 publications

Electrolyte-Induced Structural Evolution of Triton X-100 Micelles

Electrolyte-Induced Structural Evolution of Triton X-100 Micelles

Clouding behaviour in surfactant systems

Counter ion condensation on mixed cationic/nonionic micellar systems: Bjerrum's electrostatic condition

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