Thermodynamics of micelle formation: Model calculations for alkyl carboxylates

Eriksson, Folke; Eriksson, Jan Christer; Stenius, Per

doi:10.1016/0166-6622(81)80061-3

Cited by 17 publications

(13 citation statements)

References 17 publications

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“…Sodium octanoate micelles have been studied rather extensively with a wide range of methods. Friman et al22 could reconcile their potentiometric data (obtained in 3 M Na(Cl)) with any micellar aggregation number between 9 and 17, while theoretical calculations of Eriksson et al 23 gave a somewhat higher value.…”

Section: Discussionmentioning

confidence: 94%

Tracer self-diffusion studies of micelle formation of a short-chain ionic surfactant, sodium n-octanoate

Lindman¹,

Kamenka²,

Puyal³

et al. 1984

J. Phys. Chem.

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Section: Discussionmentioning

confidence: 94%

Tracer self-diffusion studies of micelle formation of a short-chain ionic surfactant, sodium n-octanoate

Lindman¹,

Kamenka²,

Puyal³

et al. 1984

J. Phys. Chem.

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“…The phenomenon is to be related to the effect of water on the micelle formation in the two solvents and [21,22] at 35 ~ The aggregation number of the soap is fairly low, not exceeding 20, and the micelle is highly hydrated, containing 6-8 moles of water per mole of sodium [23][24][25]. On the other hand, as mentioned before, the extent of aggregation in neat alcohols is rather limited, and there is a reasonable doubt whether micelle formation takes place [6-8, 23, 26, 27].…”

Section: Solubility Of Sodium Octanoatementioning

confidence: 99%

Enthalpies of solution in sodium octanoate + water + alcohol mixtures

Kertes

Tsimering

Garti

1985

Colloid & Polymer Sci

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Enthalpies of solution of sodium octanoate in water, 1-propanol and aqueous mixtures of l-propanol, 1-butanol, 1-pentanol and 1-hexanol, and of the alcohols in aqueous solutions of sodium octanoate at various concentrations were determined calorimetrically at 35 ~ Most AH(soln) values are exothermic and strongly dependent on the solute concentration. The main energetic factor governing the process of dissolution of the surfactant is associated with changes in the water structure caused by the presence of alcohol. That governing the process of the alcohol dissolution in surfactant solutions is due to the effect alcohols have on the CMC of the octanoate. There is no indication of the alcohol being either solubilized in the interior of the aqueous micelle, or becoming part of the micellar film.The solubility at 35 ~ of sodium octanoate in water, 1-propanol and their mixtures has also been determined. In the previous reports [1][2][3][4] in these series the calorimetrically determined enthalpies of solution in some model ternary colloidal systems have been interpreted in terms of solute-solvent interactions between the components. We believe we have provided considerable evidence to show that the energetics of solubilities in such simpler systems -which can be regarded as limiting cases for the more complex, four-component microemulsion -are helpful in understanding the balance of forces which define microemulsion stability. In this balance of forces the role of the alcohol cosurfactant is perhaps the most complex one. Namely, the hydrophilic -hydrophobic balance of a microemulsion is governed primarily by the extent of water or oil miscibility of the alcohol cosurfactancThe presence of any third component in aqueous solutions of ionic surfactants is known to have an effect on the micellar properties of the binary solutions. With an aliphatic alcohol as the third component the effect is generally due to any single one or a combination of the basic processes characterized as (i) the change in the solvent structure, (ii) the solubilization of the alcohol in the interior of the aqueous micelle, and (iii) the incorporation of the alcohol molecules into the O 849 micelles in the form of mixed micellar films. A separate identification of these effects is by no means trivial. Methanol or ethanol are considered to affect micelle formation by virtue of their effect on the solvent structare, and no micelles of ionic surfactants are formed in mixed aqueous solutions containing 30-40 volume percent of the alcohols [5]. Propanol and higher alcohols, which are known microemulsion cosurfactants, in contrast to methanol or ethanol, have apparently no such dramatic effect on the micellization process per se, though the degree of surfactant aggregation is probably lowered [6][7][8]. However, since their presence affects many of the overall properties of aqueous micellar solutions [9][10][11][12], even more than methanol or ethanol do, it is usually assumed that other interactions play a more important role.In an attempt t...

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“…This is consistent with experimental evidence, where the strength of ion pairing has been reported to be very weak, 43 for the shorter alkyl carboxylate anions, namely formate and acetate salts. [44][45][46] We note, however, that the short-chain salts exhibit typical 1 : 1 electrolyte behaviour, whereas salts with chains longer than C 4 exhibit increasingly atypical behaviour due to the aggregation of the anion in solution, [47][48][49][50] with critical micellar concentrations reported to decrease as the alkyl chain length is increased. 47 It is important to note that in its current formulation the SAFT-g Mie approach does not account for the formation of micelles.…”

Section: Aqueous Solutions Of Carboxylate Saltsmentioning

confidence: 76%

“…4(b) and (d)), which is related to micelle formation. [47][48][49][50] The current SAFT-g approach does not account for these aggregates, and as a result the predictions are seen to deviate from the data at higher concentrations for the butanoate and pentanoate salts. The isobaric liquid density r of aqueous sodiumcarboxylate solutions is displayed in Fig.…”

Section: Mixturementioning

confidence: 87%