Studies of soap solutions. Part II.—Factors influencing aggregation in soap solutions

Stainsby, G.; Alexander, A. E.

doi:10.1039/tf9504600587

Cited by 140 publications

(43 citation statements)

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“…(2) G 0 gem = 2 G 0 conv , where for nonionic surfactants [24][25][26][27] (3) G 0 i = RT ln CMC i , where R is the ideal gas constant, T is the temperature, and CMC i is the CMC of surfactant i in moles per liter. Substi- where CMC gem and CMC conv are the CMCs of the gemini and conventional surfactants respectively.…”

Section: Discussionmentioning

confidence: 99%

Preparation and dilute solution properties of model gemini nonionic surfactants

FitzGerald

Carr

Davey

et al. 2004

Journal of Colloid and Interface Science

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Section: Discussionmentioning

confidence: 99%

Preparation and dilute solution properties of model gemini nonionic surfactants

FitzGerald

Carr

Davey

et al. 2004

Journal of Colloid and Interface Science

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“…Our datum on the concentration of the soap in the saturated aqueous solution is in disagreement wkh the earlier [15,19] value of 40.65 wt% at 25 ~ since soap solubility in water usually increases with temperature [20]. The soap is sparingly soluble in anhydrous propanol at 35 ~ which is some 15 ~ below the Kraft point, but is dramatically increased on addition of water to the anhydrous propanol.…”

Section: Solubility Of Sodium Octanoatementioning

confidence: 94%

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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“…A phase-separation or two-phase model was often used to describe the thermodynamics of micelle formation (1)(2)(3). The two-phase model predicts a homogeneous monodisperse micellar phase and a constant monomer concentration above the CMC (4).…”

mentioning

confidence: 99%

Mechanism of micelle formation in sodium dodecyl sulfate and cetyltrimethylammonium bromide

Topallar¹,

Karadag²

1998

J Surfact & Detergents

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pH changes as a function of concentration for sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) were observed by addition of 1 N HCl and 1 N KOH. pH values increased up to the critical micellar concentration (CMC) for the SDS/HCl system and decreased for the CTAB/KOH system. In the SDS/HCl and CTAB/KOH systems, the micellar phase had a fixed composition and was homogeneous and monodisperse above the CMC. However, in the SDS/KOH and CTAB/HCl systems, pH values increased continuously and gradually below and above the CMC, and the properties of the micellar phase changed as a function of concentration, giving rise to inhomogeneity and polydispersity. JSD 1, 49-51 (1998).KEY WORDS: Cetyltrimethylammonium bromide, critical micellar concentration, hydrochloric acid, micelle formation, pH, phase separation, potassium hydroxide, sodium dodecyl sulfate.Some early investigators observed fairly abrupt changes in a number of physicochemical properties at or near the critical micellar concentration (CMC) and concluded that micelle formation had at least some of the properties of a phase change. A phase-separation or two-phase model was often used to describe the thermodynamics of micelle formation (1-3). The two-phase model predicts a homogeneous monodisperse micellar phase and a constant monomer concentration above the CMC (4). Careful experimental measurements using highly purified systems revealed that somewhat gradual and continuous changes in physicochemical properties occurred near the CMC (5-8), that micelles appeared to be polydisperse (9), and that monomer activities changed above the CMC (5,10).For example, gradual and continuous decreases in the equivalent conductance of sodium dodecyl sulfate (SDS) in water (7,11) and changes in the heats of micelle formation for alkyl carboxylates (8,12) in water have been observed. In addition, a significant decrease in surface tension was observed for SDS in water above the CMC, indicative of a change in monomer activity (5).The purpose of this investigation is to propose an explanation for micelle formation and phase separation of SDS/HCl, SDS/KOH, CTAB (cetyltrimethylammonium bromide)HCl and CTAB/KOH systems by measuring pH as a function of concentration. EXPERIMENTAL PROCEDURESSDS [CH 3 (CH 2 ) 11 OSO 3 Na], CTAB [CH 3 (CH 2 ) 15 N + (CH 3 ) 3 ]-Br − , HCl (hydrogen chloride), and KOH (potassium hydroxide) were supplied by Merck (Darmstadt, Germany) and were all of analytical grade. pH values were measured at 25°C with a digital pH meter, Model 3040 (Jenway Ltd., Felsted Dunmow Essex, United Kingdom), pH range −2 to 16.000, resolution 0.001, and accuracy ± 0.005.First, 55 mM SDS and CTAB solutions were prepared, separately, and then each solution was diluted with water from 55 to 10 mM in increments of 5 mM. For the SDS/HCl systems, first, a solution of 29.91 mL of 55 mM SDS and 0.09 mL of 1 N HCl (30 mL total) was subjected to pH measurement, and then diluted with water to 50 mM. The same amount of acid (0.09 mL of 1 N HCl) was added to this diluted sol...

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Studies of soap solutions. Part II.—Factors influencing aggregation in soap solutions

Cited by 140 publications

References 0 publications

Preparation and dilute solution properties of model gemini nonionic surfactants

Preparation and dilute solution properties of model gemini nonionic surfactants

Enthalpies of solution in sodium octanoate + water + alcohol mixtures

Mechanism of micelle formation in sodium dodecyl sulfate and cetyltrimethylammonium bromide

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