Tetramethylammonium Dodecyl Sulfate Research Articles

Nuclear Magnetic Resonance and Small-Angle Neutron Scattering Studies of Anionic Surfactants with Macrocounterions: Tetramethylammonium Dodecyl Sulfate

Micellar solutions of tetramethylammonium dodecyl sulfate have been studied to determine the degree of counterion binding. Tetramethylammonium chloride was added over a wide range of surfactant concentrations such that the total concentration of tetramethylammonium ions in solution remained constant. Small angle neutron scattering experiments showed a constancy in aggregation number across this series, consistent with the constant C(aq) concept of Bales et al. (J. Phys. Chem. B 2001, 105, 6798). Pulsed-field gradient and electrophoretic NMR experiments were used to determine the degree of counterion dissociation, alpha, which was found to be 0.33. This value is in contrast to the value from conductivity measurements (alpha = 0.2), but supports the concept of an aggregation number based definition of alpha.

The effect of counterions on the surface adsorption and micelle formation in mixed surfactant systems of dodecyl sulfates

The surface tension of the aqueous solutions of sodium dodecyl sulfate (SDS) and tetramethylammonium dodecyl sulfate (TMADS) was measured as a function of total molality of the surfactants at fixed composition of TMADS at 298.15 K under atmospheric pressure. The phase diagrams of adsorption and of micelle formation, the activity coefficients, and the excess Gibbs energy were calculated to estimate the deviation from the ideal mixing quantitatively. The preferential adsorption and the micelle formation for TMA+ to Na+ is attributable to some extent to the hydrophobicity of the methyl groups of TMA+. The composition of TMA+ in the micelle is larger than that in the adsorbed film at equilibrium. That is, a larger hydrated counterion is more likely to exist in the micelle than in the adsorbed film owing to geometrical benefit. The negative values of the excess Gibbs energy of the adsorbed film and of the micelle arise from the positive ones of the excess entropy greater than that of excess enthalpy. The counterions of very similar size are mixed ideally in the micelle and the size effect appears sensitively in the adsorbed film.

Interfacial Films and Wetting Behavior of the Air/Hexadecane/Aqueous Solution of a Surfactant System

The tension of the three interfaces and the dihedral angle of the lens of the air/hexadecane lens/aqueous solution of tetramethylammonium dodecyl sulfate (TMADS) system were measured as a function of the surfactant concentration. The air/water surface tension vs concentration curves both with and without an oil lens exhibited a break point corresponding to the phase transition of the adsorbed films. From the thermodynamic analysis, it was shown that the phase transition drives the spreading of hexadecane molecules into the adsorbed film. The dihedral angle decreased very rapidly from about 50° at zero concentration to about 6° at the phase transition point and then increased slowly to about 20° at the critical micelle concentration (cmc), suggesting the very drastic change in wetting properties at the phase transition point. The plausible gap was observed between the dihedral angles measured and those calculated from the interfacial tension values at the concentration range from just above the phase transition to near the cmc. This suggests a case where the Neumann relation does not hold even when a lens exists stably. One of the possibilities may be that the wetting film is rather thick just above the phase transition point.

The role of the counterion in poly(ethylene oxide)-dodecyl sulfate interactions

The effects of the counterions, Li +, Na + and tetramethylammonium (TMA +) of dodecyl sulfates on the interaction of poly(ethylene oxide) (PEO) have been investigated conductimetrically. For tetramethylammonium dodecyl sulfate (TMADS), significant effects on the classical conductivity vs surfactant profiles should be expected, compared to those for lithium dodecyl sulfate (LDS) and sodium dodecyl sulfate (SDS), since the main driving forces of the polymer binding should be attributed to the counterion. However, it has been found that the conductivity breakpoints, the critical aggregation concentration ( cac) and the polymer saturation point ( psp), and also other characteristics of the conductivity profiles investigated, such as linearity of the cac-psp region, ratios of slopes related to the degrees of dissociation of the polymer-surfactant complexes and micelles, and the amount of the complexed surfactant per monomol of PEO, do not exhibit differences sufficient to justify the importance of the counterion in the mechanism of polymer-surfactant interaction.

Neutron Reflection from Counterions at the Surface of a Soluble Surfactant Solution

The distribution of counterions at a charged surface has been measured directly using neutron specular reflection with isotopic labeling being used to highlight the scattering from the counterions. The system investigated was the soluble surfactant tetramethylammonium dodecyl sulfate with and without added tetramethylammonium chloride. Depending on the conditions a fraction of ions were found to penetrate the surfactant head-group region. The majority of the counterions observed formed a layer adjacent to the head-group layer which must be part of the diffuse layer. These two layers did not, however, account for all the counterions, and the remainder of the diffuse layer could not be observed with certainty. The reason for this is not understood, although it is probably associated with the roughness of the diffuse layer. Using the measured charge density and surface coverage as parameters, the counterion distribution calculated from the Stern−Gouy−Chapman model of the electrical double layer appears to account quite well for the shape of the distribution, although the effect of the “missing” ions made a detailed quantitative comparison impossible.

Evaluation of the counterion distribution around spherical micelles in solution by small-angle neutron scattering.

The counterion distribution around tetramethylammonium dodecyl sulfate micelles has been evaluated by small-angle neutron scattering (SANS) using the contrast variation technique. The scattering from the counterions and the hydrated shell was isolated by matching the scattering length densities of the core and aqueous medium by adjusting the ${\mathrm{H}}_{2}$O-to-${\mathrm{D}}_{2}$O ratio. Thus the core component of the scattering was ``erased,'' due to zero contrast with the solvent. The counterion distribution was estimated by fitting the SANS data to a model of an isolated particle consisting of a core, shell, and counterion atmosphere, with only three adjustable parameters. For a micellar concentration of 6 vol %, the aggregation number, core radius, shell thickness, and charge number were estimated as 77, 18.6 \AA{}, 4.6 \AA{}, and 44, respectively. Similar values were obtained for a concentration of 3 vol %. In addition, the electrostatic potential and the dissociation equilibrium at the micellar surface were also evaluated. The estimated value of the surface potential of micelles (-4.7kT) indicated the validity of using the numerical solution of nonlinear Poisson-Boltzmann equation for the calculation of the counterion distribution. \textcopyright{} 1996 The American Physical Society.

Effect of 1-butanol on the surface structure of ionic micelles and location of its solubilization site: Electron spin echo modulation study with x-doxylstearic acid spin probes

Electron spin echo modulation studies with a series of x-doxylstearic acids ( x = 5, 7, 10, 12, and 16) have been carried out for sodium- and tetramethylammonium dodecylsulfate and dodecyltrimethylammonium chloride frozen micellar solutions containing protiated and perdeuterated 1-butanol. Modulation effects due to nitroxide interactions with deuterium in water and butanol have been measured versus doxyl group position. The effect of 1-butanol on the micellar surface and internal micellar structure has been evaluated and the average location of 1-butanol in these micelles has been deduced to be in the outer annulus of the micelle core.

ChemInform Abstract: ESR and Electron Spin Echo Modulation Studies of N,N,N′,N′‐Tetramethylbenzidine Photoionization in Frozen Micellar Solutions: Structural Effect of 1‐Butanol Addition to Sodium and Tetramethylammonium Dodecylsulfate and Dodecyltrimethylammoninm Chloride Micelles.

ChemInform Abstract: ESR and Electron Spin Echo Modulation Studies of N,N,N′,N′‐Tetramethylbenzidine Photoionization in Frozen Micellar Solutions: Structural Effect of 1‐Butanol Addition to Sodium and Tetramethylammonium Dodecylsulfate and Dodecyltrimethylammoninm Chloride Micelles.

Electron spin resonance and electron spin echo modulation studies of N,N,N',N'-tetramethylbenzidine photoionization in frozen micellar solutions: structural effect of 1-butanol addition to sodium and tetramethylammonium dodecylsulfate and dodecyltrimethylammonium chloride micelles

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectron spin resonance and electron spin echo modulation studies of N,N,N',N'-tetramethylbenzidine photoionization in frozen micellar solutions: structural effect of 1-butanol addition to sodium and tetramethylammonium dodecylsulfate and dodecyltrimethylammonium chloride micellesEwa Szajdzinska-Pietek, Rene Maldonado, Larry Kevan, and Richard R. M. JonesCite this: J. Am. Chem. Soc. 1985, 107, 23, 6467–6470Publication Date (Print):November 1, 1985Publication History Published online1 May 2002Published inissue 1 November 1985https://doi.org/10.1021/ja00309a007RIGHTS & PERMISSIONSArticle Views53Altmetric-Citations17LEARN 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 (460 KB) Get e-Alerts Get e-Alerts

Electron spin-echo modulation studies of doxylstearic acid spin probes in sodium and tetramethylammonium dodecyl sulfate micelles: interaction of the spin probe with deuterated water and with deuterated terminal methyl groups in the surfactant molecules

Resultats d'etudes sur une serie d'acides x-doxylsteariques avec x=5, 7, 10, 12 et 16. Mise en evidence d'une forte influence des ions antagonistes et d'une grande difference entre les micelles de laurylsulfate de sodium et de laurylsulfate de tetramethylammonium