Micellar Molecular Weight Research Articles

Coacervating soap-electrolyte solutions: I. Charge properties. II. Generalized treatment of coacervating soap-electrolyte systems

The phenomenon of coacervation, i.e., separation of a homogeneous solution into two liquid layers on addition of an electrolyte to some association colloids, has been characterized previously. Comparison was made of the ionization patterns of several coacervating soap systems with those of noncoacervating systems at low added electrolyte concentrations. In noncoacervating systems, ionization increases with increasing electrolyte concentration and then levels off. In coacervating systems, ionization reaches a maximum at rather low electrolyte concentrations, followed by a rapid decrease in ionization with further additions of electrolyte. In the first case, the ionization is found to depend linearly on the square root of electrolyte concentration ( c ), whereas in the coacervating systems the ionization is proportional to ce − be , where b is a constant. These findings are explained in terms of (1) the constancy of the surface potential on addition of an electrolyte in noncoacervating systems and (2) a postulated decrease of the surface potential on addition of an electrolyte in coacervating systems. A generalized equation is developed, which gives the dependence of square root of micellar molecular weight on the reduced electrolyte concentration in the system. This equation is obeyed by several coacervating systems investigated and seems to be justified on the basis of the postulated decrease of surface potential on the addition of an electrolyte to a soap solution which forms coacervates.

Temperature studies of coacervating cationic soap solutions

AbstractThe micellar molecular weights (MMW) and the critical micelle concentration (CMC) of the homogeneous phase of the cationic coacervating soap system, Hyamine‐1622, as a function of NaCl concn and temp were determined from light scat‐tering and refractive index measurements. At constant temp, an overall two‐stage growth proc‐ess is indicated in this system. At low NaCl concn, the micelle grows to a limiting isotropic structure. At higher NaCl concn, the micellar growth is an exponential function of the NaCl concn. Temp studies of the CMC provide the basis for calculating values of the heats of micel‐lization, खHm in a limited range of NaCl concn (0‐0.06M). The temp dependence of the MMW at fixed NaCl concn in the range of 17‐47 C is an exponential function and plots of log (MMW) vs. 1/T give straight lines with positive slopes. At low NaCl concn (0‐0.8M), where there is an effective charge on the micelles, these slopes are small. At high NaCl concn, where the micelles approach zero effective charge (theta conditions), the slopes increase abruptly and remain approx constant over a wide range of NaCl concn (0.08‐0.24M).

Light scattering study of sodium 2 ,6-di-n-alkylnaphthalene-1-sulfonates

Light-scattering measurements have been carried out on sodium 2,6-di- n-octyl and sodium 2,6-di- n-dodecylnaphthalene-1-sulfonates in n-decane at 25° and 90°C. The micellar molecular weight is found to be rather insensitive to chain length and temperature, being about 10,000 at 25°C. and 8,000 at 90°C. for each compound. The micelles appear to be nearly spherical in shape and approximately 15 A. in radius. Vapor pressure lowering shows that in benzene solution the molecular weight of the sodium 2,6-di- n-dodecylnaphthalene-1-sulfonate micelle is reduced to 5,500 at 37°C. The results appear consistent with a number of findings reported in the literature for dinonylnaphthalene sulfonate systems.

The Application of the Archibald Ultracentrifugal Method to the Determination of the Micellar Molecular Weight of the Anionic Surface Active Agents

Abstract (1) The values of the micellar molecular weight of SDS in water and in a sodium chloride solution could not be obtained by the Archibald method, whereas the observed Mo may represent the relative values, each corresponding to a given instant of centrifugation. However, a CMC could be definitely determined which agreed with the values reported by other workers. As may be noted from the slope of the dependency of M0 on time, the SDS solution is non-ideal above the CMC while it is polydisperse below the CMC. The abnormally high association in the critical micelle region might be caused by the incomplete dissociation of counter ions, accompanied by a change in the equilibrium between the micelle and the free ion of SDS at a given instant of centrifugation. (2) When the electrolyte is absent, β-NF’s presumably exist in a monomeric state, but in a 0.1 m sodium chloride solution they associate, the degree of association being proportional to the x. In the region of 0.25∼1.0% concentration, micelles of β-NF were observed to be polydisperse.

The Surface Activities of Bivalent Metal Alkyl Sulfates. I. On the Micelles of Some Metal Alkyl Sulfates

Abstract Dodecyl sulfates of bivalent nickel, cobalt, copper and magnesium were synthesized, and studies were carried out on the CMC values of these detergents, the effects of the added electrolytes on these CMC values, on micellar molecular weights, and on micellar charges. The CMC values of the detergents were independent of the kind of metal, and the CMC value of 1.2×10−3 mol./l. was obtained. The micellar aggregation numbers of bivalent metal dodecyl sulfates were of the order of 100, which is about twice that of sodium dodecyl sulfate. The dissociation degrees of the micelles were also evaluated from the conductivity data. The α values obtained were 0.66 for cobalt, 0.60 for copper and 0.42 for magnesium. The dissociation degree of the copper dodecyl sulfate micelle was also estimated to be 0.52 from the depression of the CMC value by the added electrolyte; this figure is approximately the same as the value of 0.60 obtained from the conductivity data. These results suggest that the fundamental factor responsible for determining the surface activities of bivalent metal dodecyl sulfates is the valency of the gegenion and that the kind of metal has little or no detectable effect on them.

On the relation between viscosity and critical micelle concentration of detergent solutions

i) Viscosity of three kinds of aq. solution of ionic detergent, potassium caprate, sodium oleate and dodecylamine hydrochloride, is measured and CMC is calculated from viscosity number,ηsp/c, by the new method of the present authors. ii) Micellar molecular weight calculated from intrinsic viscosity by the method of the present authors coincides moderately with that from CMC and from literature. iii) The influence of diffusion potential is investigated by measuring dependence of diffusion coefficient on concentration of added electrolyte for potassium caprate and sodium oleate. It is found that its influence is larger for sodium oleate than for potassium caprate. iv) Concentration dependence of diffusion coefficient of aq. solution of potassium caprate and sodium oleate is measured. It is shown that diffusion coefficient varies suddenly near the 1st and 2nd CMC. It is also concluded that micelle is moderately monodisperse in both cases. v) Thickness of hydration layer of micelle is calculated from diffusion coefficient at the 1st CMC and micellar molecular weight from which was found that the hydration layer on micelle may be about monomolecular at most.

Nonionic surface-active compounds IV. Micelle formation by polyoxyethylene alkanols and alkyl phenols in aqueous solution

Critical micelle concentrations and micellar molecular weights, determined by light scattering, are presented for a series of commercially prepared polyoxyethylene lauryl alcohols and nonyl phenols. A relationship is shown to exist between average aggregation number and ethylene oxide mole ratio, and, on the basis of some simple assumptions, a rod-shaped micelle is shown to be most likely at long ethylene oxide chain lengths, whereas there is little to choose between a rod, disc, or sphere for short polyoxyethylene chains.

On the micellar molecular weights of normal paraffin chain salts in dilute aqueous solutions

The micellar molecular weights of four normal paraffin chain salts in dilute aqueous solution have been revised to give the values: dodecyltrimethylammonium bromide, 12200; sodium decyl sulfate, 9300; sodium dodecanesulfonate, 12300; sodium dodecyl sulfate, 11500. A reference model of a spherical micelle has been proposed. The MMW's estimated with its use show substantial agreement with the experimental values, except for C 12 salts. The MMW's of spherical micelles of C 16 salts have been predicted and verified experimentally. The data on alkyl pyridinium bromides indicate that the radius of the sperical micelle is equal to the alkyl chain length.

On the Relation between Viscosity and Critical Micelle Concentration of Detergent Solutions. III. Relations between Micellar Molecular Weight, Viscosity and Critical Micelle Concentration of Detergent Solutions

Abstract 1) The following equation is found between association number (n) and critical micelle concentration (Cc in mol./1.) in detergent solutions n=17.0×(1/C_c)^0.29 This relation holds, independent of an-ionic and cationic detergents and added electrolytes. 2) The following equations are found between micellar weight (Mm) and two kinds of intrinsic viscosity ([η1] and [η2]) already reported in the previous paper. & logM_m=0.41{logn[η_1]}^2 & -0.39{logn[η_1]}+3.47 & logM_m=0.45{logn[η_2]}^2 & -0.91{logn[η_2]}+4.04 These relations are applicable, not only to ionic- but also to non-ionic detergents. 3) Discussions are made on the cause of characteristic behavior of viscosity at CMC. This phenomenon seems to be due to adsorption of detergent molcules to the wall of viscometer.

Micellar Molecular Weights of Some Paraffin Chain Salts by Light Scattering

ADVERTISEMENT RETURN TO ISSUEArticleNEXTMicellar Molecular Weights of Some Paraffin Chain Salts by Light ScatteringH. V. Tartar and A. L. M. LelongCite this: J. Phys. Chem. 1955, 59, 12, 1185–1190Publication Date (Print):December 1, 1955Publication History Published online1 May 2002Published inissue 1 December 1955https://doi.org/10.1021/j150534a001RIGHTS & PERMISSIONSArticle Views186Altmetric-Citations84LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (665 KB) Get e-Alerts

Micellar Molecular Weights of Selected Surface Active Agents

Micellar Molecular Weights of Selected Surface Active Agents

On the Relation Between Viscosity and Critical Micelle Concentration of Detergent Solutions. II. Viscosity and Diffusion Coefficient of Non-ionic Detergent Solutions

Abstract (1) Partial specific volume, viscosity, diffusion coefficient of the aqueous solutions of non-ionic detergents are measured. (2) ηsp/C becomes minimum at CMC and this concentration is quite consistent with the concentration where diffusion coefficient varies suddenly. It is interesting that this is the common phenomenon for ionic and non-ionic detergents. (3) The form of ηsp0/C0 vs C0-Curve is analogous to that described in the first report and the second CMC (C2) is also obtained but some abnormality occurs in the part of low concentrations for the substance of which CMC is high. (4) After the completion of micelle formation, diffusion coefficient stays constant and is independent of concentration which suggests that micellar volume is constant and independent of concentration. (5) The influence of an electrolyte on the diffusion is examined and a new idea of the mechanism of “salting out” is proposed. (6) Micellar molecular weight is calculated from the diffusion coefficient assuming that a micelle is spherical.