Thermodynamics of mixed micelles: Determination of the aggregate composition

Letellier, Pierre; Mayaffre, Alain; Turmine, Mireille

doi:10.1016/j.jcis.2008.08.010

Cited by 19 publications

(16 citation statements)

References 31 publications

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“…The composition of mixed micelles must be experimentally determined [2] or calculated. We introduced simple solutions to reach it without using a modeling of the physicochemical properties of the system, a priori [3].…”

Section: Introductionmentioning

confidence: 99%

Thoughts on the ideal behavior of mixed micelles and the appropriate application of regular solution theory (RST)

Letellier¹,

Mayaffre²,

Turmine³

2011

Journal of Colloid and Interface Science

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Solutions of mixed surfactants are often considered as solvent mixtures. Usually, mixed micellar aggregates are considered as a homogeneous mixture of solvents dispersed in a solution. But the transposition of the usual thermodynamic models of solvent mixtures to mixed micelles is not always so obvious. We discussed this point in this paper by considering several cases of surfactant mixtures. A major problem is to define the molar fraction of each surfactant in the aggregate especially when a charged surfactant is employed in the mixture, because possible dissociation of the components of the mixture must be considered in the bulk as well in the micelle. This definition is crucial especially for the characterization of the ideal behavior which is usually described by the Clint relation, as well as for the application of regular solution theory (RST) which is the most frequently applied model for interpreting the behavior of surfactant mixtures. We show in this paper how the definition of the molar fraction can change the equations and the interpretations.

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Section: Introductionmentioning

confidence: 99%

Thoughts on the ideal behavior of mixed micelles and the appropriate application of regular solution theory (RST)

Letellier¹,

Mayaffre²,

Turmine³

2011

Journal of Colloid and Interface Science

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“…However, for deriving eq , it can be assumed that the molar Gibbs energy is described with a symmetric first-order Margules function eq . , Rodenas et al developed the method for determination of the molar fraction of the surfactant of the binary mixed micelle without a preliminary assumption on the shape of the function of the molar excess Gibbs energy eq (Table ). − From eqs – the model-independent excess Gibbs energy, that is, function g E = f ( x i mM ) − that fits the second-order Margules function can be determined. In fitting g E ( x i mM ) where used points that clearly exist x i = 0 → g ij e = 0 ∧ x i = 1 → g ij e = 0. , …”

Section: Resultsmentioning

confidence: 99%

Activity Coefficient of Triton X100 and Brij S20 in the Infinitely Diluted Micellar Pseudophase of the Binary Micelle Triton X100–Brij S20 in the Water Phase at the Temperature Interval T = (283.15–318.15) K

Poša

Pilipović

2019

J. Chem. Eng. Data

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Activity coefficients of the infinitely diluted micellar pseudophase are equal to parameters of the second-order Margules function: ln φ i ∞ = a ij and ln φ j ∞ = a ji . The excess chemical potential of the infinitely diluted micellar pseudophase can be expressed using partial molar enthalpy (h i E,∞) and entropy (s i E,∞), extrapolated in the infinitely diluted state: μ i E,∞ = RT ln φ i ∞ = h i E,∞ – Ts i E,∞. The binary mixture of surfactants Triton X100–Brij S20 is not a symmetric binary mixture. In the temperature interval T = (283.15–318.15) K, the activity coefficient for Triton X100 = i in the infinitely diluted micelle pseudophase is ln φ i ∞ < 0; also, the activity coefficient for Brij S20 = j in the infinitely diluted micellar pseudophase is ln φ j ∞ < 0. Thermodynamic stabilization related to the hypothetical ideal state in the infinitely diluted state of the micellar pseudophase, originating from the limit value of the chemical potential in the case of Triton X100, is of the entropic origin (s i E,∞ > 0, h i E,∞ > 0), while for Brij S20, it is of the enthalpy origin (s j E,∞ < 0, h i E,∞ < 0).

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“…We showed in a previous study [12] that thermodynamic relations allow accessing to this extent without using a model of presupposed behaviour of micellar mixture.…”

Section: Application Of the Bet Model To Mixed Charged And Uncharged mentioning

confidence: 99%

“…We showed recently [12] that, for surfactant mixtures, this is straightforward because the values of the aggregation thresholds are known for amphiphile mixtures at various compositions in solution. When these variables are available, the applicability of classical models of behaviour of binary mixtures (one of them being the RST) can be examined and that which best fits the studied case can be chosen (or it can be noted that none fit).…”

Section: Introductionmentioning

confidence: 99%

Mixing behaviour of charged and non-charged surfactants described by BET isotherms

Letellier

Mayaffre

Turmine

2009

Journal of Colloid and Interface Science

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Thermodynamics of mixed micelles: Determination of the aggregate composition

Cited by 19 publications

References 31 publications

Thoughts on the ideal behavior of mixed micelles and the appropriate application of regular solution theory (RST)

Thoughts on the ideal behavior of mixed micelles and the appropriate application of regular solution theory (RST)

Activity Coefficient of Triton X100 and Brij S20 in the Infinitely Diluted Micellar Pseudophase of the Binary Micelle Triton X100–Brij S20 in the Water Phase at the Temperature Interval T = (283.15–318.15) K

Mixing behaviour of charged and non-charged surfactants described by BET isotherms

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