Solutions Of Sodium Decyl Sulfate Research Articles

Thermodynamics and Structure of Micelles in Aqueous Solutions of Sodium Decyl Sulfate in the Region of the Third Critical Micelle Concentration

Using data on heat capacity of sodium decyl sulfate solutions near the third critical micelle concentration, obtained earlier via high-precision scanning calorimetry, the temperature dependences are calculated for the thermodynamic functions of the corresponding micellar transition and the components of its Gibbs free energy. It is shown that the considered intermicellar transition, interpreted as the micellar shape transforming from cylindrical to lamellar as the concentration grows, occurs at an equilibrium molality of 0.33 and a temperature of 323 K. Correlations between the thermodynamic functions of the transition with structural changes in the micelles and the key micellar parameters are discussed.

Properties of Micellar Solutions of Sodium Decyl Sulfate at Relatively High Concentrations

Heat capacities of aqueous solutions of anionic surfactant sodium decyl sulfate in the 0.28–0.42 mol kg−1 range of molar concentrations and the 278–363 K range of temperatures are studied via precision adiabatic differential scanning microcalorimetry. Specific and apparent heat capacities of solutions at intervals of 0.01 mol kg−1, partial molar heat capacities of the solute and the solvent, and excess partial molar heat capacities are plotted as functions of concentration and temperature. The Kraft boundary is determined. Analysis of the characteristic changes in the above properties reveals structural changes in sodium decyl sulfate micelles that correspond to their shape transforming from cylindrical to plate-like in the region of the third critical micelle concentration.

Surface rheology and its relation to foam stability in solutions of sodium decyl sulfate

The anionic surfactant sodium decyl sulfate (SDeS) at concentrations below its critical micellar concentration (cmc) was studied in a surface chemically purified state at the air–water interface in terms of its static and dynamic interfacial properties. Equilibrium surface tension was determined using a pendant drop tensiometer. An oscillating bubble capillary pressure tensiometer allowed accessing the surface dilatational properties of the surfactant's adsorption layers in a frequency range from 2 to 500Hz. The estimation of single foam lamella stability was obtained from visual observation of films formed within a rectangular glass frame in a saturated atmosphere. Upon increasing surfactant concentration, the foam lamellae were found to rupture at prolonged lifetimes. The dramatic difference in foam stability goes along with a pronounced transition from a surface elastic to a surface visco-elastic state of the adsorption layers. These findings were indicative for a correlation between foam lamella stability and surface viscoelasticity also for this model surfactant. These results may be of importance to further shed light on the processes governing foam and foam lamella stability.

Объемные свойства растворов децилсульфата натрия в области трансформации формы мицелл

Объемные свойства растворов децилсульфата натрия в области трансформации формы мицелл

Conductance of aqueous sodium decyl sulfate solutions and the nature of hydration of the decyl sulfate anion

A study is made of the temperature and concentration dependences for conductance of aqueous sodium decyl sulfate solutions. The nature of hydration of the decyl sulfate anion is discussed within the theories proposed by Samoilov, Gurikov, and Krestov. An analysis is performed of the influence of the hydration type on the critical micelle concentration. The analysis suggests that an increase in temperature stimulates micelle formation given that hydration is negative.

Wettability of Polymeric Solids by Aqueous Solutions of Anionic and Nonionic Surfactant Mixtures

Measurements of the surface tension (γ LV) and advancing contact angle () on poly(tetrafluoroethylene) (PTFE) and poly(methyl methacrylate) (PMMA) were carried out for aqueous solutions of sodium decyl sulfate (SDS) and p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycol) (TX100) and their mixtures. The results obtained indicate that the values of the surface tension and contact angles of solutions of surfactants on PTFE and PMMA surfaces depend on the concentration and composition of the surfactant mixtures. Calculations based on the Lucassen-Reynders equation indicate that for single surfactants and their mixtures at a given concentration in the bulk phase the values of surface excess concentration of surfactants at water–air and PTFE–water interfaces are nearly the same, so the adsorption of the surfactants at water–air and PTFE–water interfaces should also be the same. However, the adsorption of TX100 and its mixtures with SDS at water–air interface is higher than that at PMMA–water interface, which is confirmed by the ratio of absolute values of molecular interaction parameters at these interfaces calculated on the basis of Rosen approach. If we take into account the hydration of the poly(ethylene oxide) chains of TX100 and acid and base parameters of the surface tension of water it appears that the PMMA surface is covered by the 'pure' water molecules from the solution or molecules connected with the chain of nonionic surfactant. On the other hand, the lack of SDS molecules at the PMMA–water interface may result from the formations of its micelles which are connected with the TX100 chain.

Thermodynamic study of sodium decyl sulfate solutions in the region of second critical micelle concentration: 2. Thermodynamic functions of polymorphic micellar transition and components of its Gibbs energy

Temperature dependences of the thermodynamic functions of polymorphic micellar transition in the region of second critical micelle concentration are calculated based on data on heat capacities of sodium decyl sulfate solutions obtained previously by scanning calorimetry. Equilibrium constants and fractions of surfactant molecules aggregated into spheroidal and cylindrical micelles are calculated. Using the models of the ellipsoid of revolution and cylinder, components of the equilibrium Gibbs energy of intermicellar transition are calculated.

Thermodynamic study of sodium decyl sulfate solutions in the region the second critical micellization concentration: 1. Volumetric and heat capacity properties

Densitometry and precision adiabatic scanning calorimetry are used to reveal a number of volumetric and heat capacity properties of sodium decyl sulfate in the region of the second critical micelle concentration. Heat capacities are established in a wide temperature range. The coefficients of thermal expansion, apparent and partial mole expandabilities, volume, heat capacities, and excess partial mole heat capacities are calculated. The analysis of variations in these thermodynamic properties occurring upon variations in concentration and temperature makes it possible to identify the structural variations in sodium decyl sulfate micelles that are relevant to the transition of micelles from globular to cylindrical forms.

Adsorption of Binary Mixtures of Anionic Surfactants at Water–Air and Poly(Tetrafluoroethylene)–Water Interfaces

AbstractMeasurements of the surface tension (γLV) and the advancing contact angle (θ) on poly(tetrafluoroethylene) (PTFE) were carried out for aqueous solutions of sodium decyl sulfate (SDS) and sodium dodecyl sulfate (SDDS) and their mixtures. The results obtained indicate that the values of the surface tension and the contact angle of solutions of surfactants on PTFE surface depend on the concentration and composition of the surfactants mixture. On the curves presenting the relationship between the surface tension, contact angle and monomer mole fraction of SDDS (α) in the mixture of SDDS and SDS, there is a minimum at α equal to 0.8 which together with the negative values of the interaction parameters indicate that synergism occurs in surface tension and contact angle reduction almost in the range of concentration corresponding to the saturated monolayer of surfactants at the water–air interface. The results and calculations obtained also indicate that for single surfactants and their mixtures at a given concentration in the bulk phase, the values of surface excess concentration of the surfactants at water–air and PTFE–water interfaces are nearly the same, which suggests that the orientation of SDDS and SDS molecules at both interfaces in saturated monolayer should be vertical to the interfaces. Taking into account the values of the monomer mole fractions of the surfactants in a mixed monolayer at the water–air interface and values of the contact angle of a single surfactant on the PTFE surface, it is possible in a simple way to predict the values of the contact angle of a mixture at a given concentration and composition.

Thermodynamics of Micellization of Aqueous Solutions of Binary Mixtures of Two Anionic Surfactants

The thermodynamics of micellization of mixed anionic/anionic surfactant solutions, that is, sodium dodecyl sulfate (SDDS) and sodium decyl sulfate (SDS), have been studied by surface tension, density, and conductivity measurements. The obtained results indicate that the values of critical micelle concentration strongly depend on the composition of the mixture and that the mole fraction of surfactants in the mixed micelle calculated on the basis of Rosen and Villeneuve approaches are different from those in the bulk phase. The small negative deviation from the linear relationship between the critical micelle concentrations and composition of SDDS and SDS mixtures in the bulk phase, the values of the molecular interaction parameters, activity coefficients, and the excess Gibbs energy of mixed micelle formation calculated on the basis of Rosen and Villeneuve approaches and calculations based on the MT theory of Blankschtein proved that there is synergism in mixed micelle formation of aqueous solutions of SDDS and SDS. It was also found that the values of the standard Gibbs energy of micellization for the mixture of these two surfactants which confirm the synergetic effect can be predicted on the basis of the proposed equations which include the values of the mole fraction of surfactant in the mixed micelle and excess Gibbs energy of micellization of SDDS and SDS. Knowing the values of mole fractions of surfactants in the mixed micelle, it is also possible to calculate the volume change of surfactants after the micellization process.

Complex Formation between Poly(vinylpyrrolidone) and Sodium Decyl Sulfate Studied through NMR

Recent experimental studies have shown a preferential interaction of poly(vinylpyrrolidone) (PVP) toward the alkyl sulfate surfactants rather than toward those belonging to the alkyl sulfonate series. To gain information on the complex formation between PVP and the alkyl sulfate surfactants, we have performed 1H and 13C NMR and NOESY measurements on aqueous solutions of sodium decyl sulfate (C10OS) in the presence and absence of PVP at 1wt %. The results show that C10OS interacts with PVP, forming micelle-like clusters bound onto the polymer, and furthermore suggest that the PVP−C10OS complex formation implies the synergic effects of the electrostatic attractions between the surfactant headgroup and the nitrogen and oxygen atoms in the pyrrolidone ring of PVP and of the hydrophobic interaction between the surfactant alkyl moiety and the ring carbons of PVP.

Kinetic Study of Sodium Decyl Sulfate Solutions by the Capillary Wave Method

The capillary wave method has been applied to aqueous solutions of sodium decyl sulfate (SDes). The damping coefficient increased monotonically with concentration below the critical micelle concent...

Helix Formation of Poly(l-ornithine) in Decyl and Dodecyl Sulfate Solutions

Abstract Structural changes in poly(l-ornithine)[(Orn)n] were studied in solutions of sodium decyl sulfate (NaDecSO4) by the curve-fitting method of circular dichroism. In the NaDecSO4 concentration range from 4 to 9 mmol dm−3, only the β-structure was found. Below and above this concentration range, however, the α-helical structure was formed slightly, its fraction being less than 20%. The addition of 1-octanol enhanced the helix formation in the (Orn)n–NaDecSO4 complex.

Secondary structures of bovine serum albumin in anionic and cationic surfactant solutions

Secondary structure changes of bovine serum albumin were examined in solutions of sodium decyl sulfate (SDeS), sodium dodecyl sulfate (SDS), decyltrimethylammonium bromide (DeTAB), dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), and hexadecyltrimethylammonium bromide (HTAB). The relative proportions of α-helix, β-structure, and random coil were estimated by simulating a mixed circular dichroism (CD) spectrum of reference spectra of the corresponding structures to the experimentally obtained spectrum of the protein. The helical proportion of the protein was 66% at neutral pH. This helical proportion of the protein decreased to 52% in SDeS, to 50% in SDS, to 51% in DeTAB, to 49% in DTAB, and to 47% in TTAB and HTAB. All of these surfactants caused changes in the helical proportion from 66 to approximately 50%. However, the shorter the hydrocarbon chain a surfactant had, the higher the concentration necessary to cause the same decrease in the helical proportion. The results also indicate that the longer the hydrocarbon chain of the surfactant the greater the decrease in the helical proportion. In this study the proportion of β-structure increased slightly in every surfactant solution except DeTAB. The well-known complexes AD n (A = BSA, D = SDS, n = 40–55) and AD 2 n are formed when the helical proportion of BSA decreases to 62 and 54%, respectively. The authors speculated, on the basis of Brown's model, which segments of the helix in BSA unfold in surfactant solutions.

Chemical relaxation studies in micellar solutions of sodium alkyl sulfates

Pressure-jump-induced chemical relaxation measurements were carried out with solutions of sodium decyl sulfate (SDeS), sodium dodecyl sulfate (SDS), and sodium tetradecyl sulfate (STS). In pure SDeS solution no relaxation effect could be observed in the time range of the pressure-jump technique, whereas by adding a small amount of decyl alcohol, typical relaxations were observed which gave τ −1 increasing linearly with SDeS concentration. In pure SDS solution only one relaxation was observed which yielded τ −1 almost independent of SDS concentration. In pure STS solution, two well-separated relaxation processes were observed. The slow relaxation time ( τ 2) was almost independent of the concentration, while the reciprocal of the fast relaxation time ( τ 1 −1) increased linearly with the concentration. τ in pure SDS and in SDeS with added decyl alcohol and τ 2 in pure STS were interpreted as those associated with the micelle-forming process, while τ 1 in pure STS was interpreted as that associated with the so-called exchange process. The effects of added long chain alcohol on τ were also studied for SDS and STS. A discussion of the present results on STS was attempted according to several models which were proposed previously.

Surface active anions in polar solvents: I. Conductometric studies on solutions of sodium decyl and dodecyl sulphate in water, N,N‐Dimethylformamide, and dimethyl sulfoxide

AbstractConductivity measurements of solutions of sodium decyl sulfate and sodium dodecyl sulfate were made in water, N,N‐dimethylformamide, and dimethyl sulf‐oxide at 25 C. Within the concentration range 1 to 100 millimoles, the surfactants were found to form micellar aggregates. The critical micelle concentration values were found to depend on the dielectric constant of the medium and also on the hydrogen bonding nature of the solvent. The role of hydrogen bonding nature of the solvent in micelle formation is discussed.

Electric conductivity of sodium decyl sulfate solutions

A modified method of preparing the sodium decyl sulfate based on the insolubility of its alcoholate is described, and conductivity measurements in the highly dilute region and in the c.m.c. region in water and in the presence of salt are reported. The behavior of this compound seems quite normal throughout and it shows no indication of marked dimerization.