Sodium Decyl Sulfate Research Articles

Amphiphilic Compounds as Antihemolytic Agents: Problems and Prospects

In this research the effect of surface-active substances belonging to different classes of amphiphilic compounds (cationic trifluoperazine (TFP), anionic sodium decyl sulfate (C10) and nonionic decyl-β,D-glucopyranoside (DGP)) on the level of damage of human erythrocytes during posthypertonic shock (PHS) and glycerol removal from cells frozen to –196°C was study. All amphiphilic compounds in low concentrations (at which the antihemolytic activity is approximately 45% under the conditions of PHS cells) show the same efficiency when removing glycerol from thawed cells. It was established that among amphiphilic compounds in effective concentrations the maximum antihemolytic (AHmax) activity was shown by DGP (74%) during the removal of glycerol from thawed cells and C10 (74%) under conditions of PHS of erythrocytes, while the AHmax activity indicators of TFP were comparable in both cases. A feature of the effectiveness of C10 under the conditions of deglycerolization of cryopreserved erythrocytes is almost the same AH when used in both concentrations. The method of flow cytometry showed that the amount of annexin-labeled cells depended on the concentration of C10 both in physiological solution and under PHS conditions.

Вплив амфіфільних сполук на форму та ериптоз еритроцитів людини в умовах постгіпертонічного шоку

The search for protective substances that can be used during red blood cell thawing and the study of their effects on red blood cells contribute to increasing the number and quality of viable cells after the cryopreservation cycle. We studied the effect of posthypertonic shock and amphiphilic compounds on the shape and eryptosis of human erythrocytes. The method of flow cytometry was used, this allows analyzing two parameters simultaneously, which increases the efficiency of research. The shape was assessed by the sphericity index (SphI), and eryptosis by the redistribution of phosphatidylserine to the membrane outer surface. It has been shown that sodium decylsulfate and chlorpromazine reduce erythrocyte damage in posthypertonic shock by 3.6 and 4.2 times, respectively. Sodium decylsulfate helps to preserve the shape of cells (SphI coefficient remains the same), while when chlorpromazine is used, the shape changes towards spherical (SphI coefficient changes 2 times). The study of the level of Annexin V FITC binding to phosphatidylserine in outer layer of membrane revealed a concentration-dependent increase in fluorescence when sodium decylsulfate was used, indicating a disorder of the bilayer asymmetry. In contrast, chlorpromazine did not change the distribution of phosphatidylserine. Comparison of two parameters of cell viability - the sphericity coefficient and anexin binding - allowed us to choose the conditions that are optimal for the use of the studied protective substances. Namely, it is advisable to use the lowest effective concentration of sodium decylsulfate (200 mcmol/l) for protective purposes. This ensures the preservation of the cell shape and minimal impact on the membrane asymmetry.

Actual Amount Adsorbed as Estimated from the Surface Excess Isotherm.

The amount of adsorption at equilibrium is commonly used for reporting solid/solution isotherms, despite the admonishment by the International Union of Pure and Applied Chemistry (IUPAC) against equating the surface excess (i.e., the measurable quantity for sorption, signifying the competitive sorption of adsorbate and solvent) with the actual amount adsorbed. The consensus, more generally stated, is that the surface excess cannot be divided into individual isotherms for sorbate and solvent unless simplifying model assumptions are introduced. Here we show, contrary to the IUPAC report, that there exists a simple method for assigning the total isotherm to the sorbate's actual amount adsorbed and to the individual solute isotherm. This requires a combination of isotherm and volumetric measurements. For dilute sorbates, we establish criteria to show if the total isotherm is dominated by the amount of sorption at the interface, in agreement with the common assumption in the practical literature. In the absence of the volume data, we propose an approximate yet more versatile method based on the specific surface area to carry out order-of-magnitude analysis to examine whether the actual amount adsorbed dominates surface excess. Application of our methods to the adsorption of sodium decyl sulfate on polystyrene latex, malachite green on activated carbons, and thiophenes on a metal-organic framework all demonstrated the dominance of the actual amount adsorbed, significantly simplifying isotherm analysis in terms of the underlying interactions (i.e., surface-sorbate and net self-interactions at the interface), eliminating the need for excess surface quantities. Analysis of fully miscible solvent-sorbate isotherms (e.g., the mixtures of organic solvents adsorbed on mesoporous silica and carbonaceous adsorbents) indicates the contributions from both sorbate and solvent isotherms.

ВЛИЯНИЕ УЛЬТРАЗВУКА НА ИЗМЕНЕНИЕ ОБЪЕМНОЙ ДОЛИ ЖИДКОСТИ В ПЕНЕ И ЕЕ УСТОЙЧИВОСТЬ

The wave method of acting on matter has long been an area of intense scientific and technological research. Ultrasonic dispersion allows to obtain various highly dispersed, homogeneous and chemically pure suspensions of solid particles in liquids; accelerates and improves the process of obtaining emulsions; ultrasonic waves of different frequencies create conditions for obtaining the structure of the material, which is characterized by isotropy of certain properties. However, the mechanism of action on dispersed systems, namely Pickering systems, is not well understood today. In this work, a study of the variation of liquid volume fraction and stability of bulk foam and its monolayers has been carried out to determine the features and nature of the failure of this dispersed system under wave action. The dependence of foam multiplicity and stability on the concentration and nature of solid particle-stabilizers (titanium oxide, clay, Aerosil-380), as well as on the content and structure of surfactant modifiers (anionic surfactant sodium decyl sulfate, cationic surfactants hexylamine and cetyltrimethylammonium bromide) is shown. The increase in the concentration of solid particles led to an increase in the resistance of foams to ultrasonic actions. The study of changes in the multiplicity and stability of foams at changing the concentration of water repellent showed that the maximum resistance to ultrasonic impacts was observed not at the maximum concentration of surfactant, but at the concentration corresponding to the maximum contact angle of wetting of particles (540). The use of long-chain surfactant cetyltrimethylammonium bromide increased the stability of the foam layer to ultrasonic action at a lower (compared to hexylamine) degree of modification of the surface of solid particles.

Biotransformation of t-butyl phenols by micellar nanoreactors of peroxidase/ionic surfactants at mild conditions: nanobiocatalyst performance and kinetic analysis

Recently, some bulk reaction media were substituted by micellar systems. Micellar media can be created by different types of surfactants which generate micellar nanoreactors for diverse reactions. Ionic surfactants can be used as aqueous micellar systems, providing mild conditions for the specified reactions. Ionic surfactants: sodium dodecyl sulfate, sodium decyl sulfate (SDeS), sodium octyl sulfate (SOS), n-dodecyl trimethyl ammonium bromide, and cetyltrimethylammonium bromide were used to prepare aqueous micellar and entrapped peroxidase nanoreactors as biocatalysts. Oxidative coupling reactions were investigated for a series of phenolic hydrogen donors including 2-tert-butyl phenol, 4-tert-butyl phenol, and 2,4-tert-butyl phenol catalyzed by micellar nanoreactors of horseradish peroxidase (HRP) with hydrogen peroxide and/or tert-butyl peroxide as oxidants. Higher oxidation reaction rates were obtained for 2-tert-butylphenol and 4-tert-butylphenol with hydrogen peroxide in 90 mM SDeS (SDeS90) and 150 mM SOS (SOS150) nanoreactors, respectively. Among the micellar nanoreactors studied, the SDeS90 nanoreactor showed excellent protection of the enzyme against the peroxide inactivation effect. The long-term activity of the HRP/SDeS90 nanobiocatalyst was related to the gradual diffusion of peroxide into the nanoreactor. The biocatalytic kinetic parameters: V max, k cat, catalytic efficiency, and suicide-peroxide inactivation rate constants were determined for HRP/SDeS90. Reactions were carried out successfully under mild conditions in the micellar nanoreactors. Results confirmed that substituted functional groups on the benzene ring affect the oxidative reaction routes and products. Excellent protection of the enzyme, enhanced biocatalytic parameters, higher selectivity, and yield, in the peroxidative coupling of alkylphenols, reveal the high potential of such micellar nanoreactors for diverse organic synthesis and biotransformation.

Роль енергетичного статусу клітини у протектуванні постгіпертонічного гемолізу амфіфільними речовинами

The effect of ATP depletion on the protection of rabbit eryth- rocytes by amphiphilic substances in posthypertonic shock conditions was studied. For this, the level of hemolysis in posthypertonic shock of native and ATP-depleted erythrocytes in the presence of amphiphilic substances was determined. It was shown that ATP depletion reduces posthypertonic cell damage by 15-17% both at 0°С and at 37°С. It was found that amphiphilic compounds are able to protect rabbit erythrocytes in conditions of posthypertonic shock, but only at a temperature of 0°С. In conditions of ATP-depletion of cells, only anionic sodium decyl sulfate and nonionic decyl-β,D-glucopyranoside retain their protective effect in posthypertonic shock condi- tions, whereas cationic chlorpromazine and trifluoroperazine lose this ability. This can be explained based on the features of the incorporation of amphiphiles into the erythrocyte membrane. All studied amphiphilic compounds increase the level of damage in both control and ATP-depleted cells under conditions of posthypertonic shock at a temperature of 37°C. Probably, easier intercalation and increased fluidity of the membrane at this temperature destabilize the bilayer and reduce the protective effect of amphiphilic compounds.

Affinity and putative entrance mechanisms of alkyl sulfates into the β-CD cavity

Cyclodextrins (CDs) are novel pharmaceutical excipients and are widely used in the pharmaceutical industry and drug delivery due to their ability to form host–guest complexes. There are countless structural features of guest molecules responsible for the efficiency of guest–CD interactions. Among these factors, the hydrophobic moieties of a guest and their size are commonly considered to govern its binding affinity to CD molecules. Experimentally, it is often challenging to extract structural and dynamic information at the atomic scale about CD inclusion complexes, especially in the aqueous phase. Therefore, this study consisted of experimental (isothermal titration calorimetry and conductometric titration) and in silico analysis to rigorously characterize the interactions of β -CD with three alkyl sulfates of different hydrophobic chain lengths: sodium dodecyl sulfate (S12S), sodium decyl sulfate (S10S) and sodium octyl sulfate (S8S) in aqueous solutions. We find that the hydrophobic interactions are not always a key factor leading to the formation of stable inclusion complexes. Our results demonstrate that van der Waals interactions contribute more to complexation efficiency for sulfates with a longer hydrophobic tail, whereas electrostatic interactions are more pronounced for sulfates with shorter ones. Furthermore, we propose and discuss for the first time the putative mechanisms of the guest entering the host cavity conditioned by the lengths of hydrocarbon chains of alkyl sulfates. Finally, we prove that different types of inclusion complexes can exist in a conformational equilibrium depending on the size of a guest tail.

Studying the Mechanics of Membrane Permeabilization through Mechanoelectricity.

In this research, real-time monitoring of lipid membrane disruption is made possible by exploiting the dynamic properties of model lipid bilayers formed at oil-water interfaces. This involves tracking an electrical signal generated through rhythmic membrane perturbation translated into the adsorption and penetration of charged species within the membrane. Importantly, this allows for the detection of membrane surface interactions that occur prior to pore formation that may be otherwise undetected. The requisite dynamic membranes for this approach are made possible through the droplet interface bilayer (DIB) technique. Membranes are formed at the interface of lipid monolayer-coated aqueous droplets submerged in oil. We present how cyclically alternating the membrane area leads to the generation of mechanoelectric current. This current is negligible without a transmembrane voltage until a composition mismatch between the membrane monolayers is produced, such as a one-sided accumulation of disruptive agents. The generated mechanoelectric current is then eliminated when an applied electric field compensates for this asymmetry, enabling measurement of the transmembrane potential offset. Tracking the compensating voltage with respect to time then reveals the gradual accumulation of disruptive agents prior to membrane permeabilization. The innovation of this work is emphasized in its ability to continuously track membrane surface activity, highlighting the initial interaction steps of membrane disruption. In this paper, we begin by validating our proposed approach against measurements taken for fixed composition membranes using standard electrophysiological techniques. Next, we investigate surfactant adsorption, including hexadecyltrimethylammonium bromide (CTAB, cationic) and sodium decyl sulfate (SDS, anionic), demonstrating the ability to track adsorption prior to disruption. Finally, we investigate the penetration of lipid membranes by melittin, confirming that the peptide insertion and disruption mechanics are, in part, modulated by membrane composition.

Вплив трифторперазину та децилсульфату натрію на осмотичний шок еритроцитів людини та кролика

The effects of trifluoroperazine and sodium decyl sulfate on posthypertonic shock of human and rabbit erythrocytes were studied. For this purpose, the level of hemolysis in posthypertonic shock and the percentage of potassium ions released from erythrocytes in dehydration and rehydration solutions in the presence of trifluoroperazine and sodium decyl sulfate were determined. It is shown that the protective effect of amphiphilic compounds is manifested at 0°C, but not at 37°C. There is a decrease in the level of hemolysis in a certain concentration range of each of the studied substances. It was found that human erythrocytes are more sensitive to the protective action of the studied amphiphilic compounds and are characterized by a wider range of protective concentrations. This could be explained by the different lipid composition of the erythrocyte membranes of the studied mammals. Measurement of the leak of potassium ions in dehydration and rehydration media in the presence of amphiphilic compounds suggested that the latter do not affect the permeability of the membrane of mammalian erythrocytes for potassium in posthypertonic shock. Based on the obtained results and literature data, it is assumed that the protective effects of trifluoroperazine and sodium decyl sulfate occur independenly of the formation of temporary defects in permeability for potassium ions, but involve an increase in the cell surface area due to the incorporation of amphiphilic molecules. This results to an increase in the critical hemolytic volume of erythrocytes and reduction in the level of damage during change from hypertonic conditions to isotonic ones.

A New Saquinavir Mesylate-Sodium Decyl Sulfate Salt Discovered by Serendipity during an Anomalous Dissolution Test.

To understand the anomalous behavior of Saquinavir Mesylate (SQVM) in sodium decyl sulfate (SDS) medium during a dissolution test through a crystallographic analysis of the crystal obtained. As a result, it will be possible to elucidate its crystal structure and carry out a complete solid-state characterization of the API. The solid form obtained was characterized by a structural analysis through X-ray single crystal and powder diffraction. The crystallographic structures of the new salt and the SQVM were compared. In addition, a complete solid-state characterization of SQVM raw material was carried out by techniques such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), Raman spectroscopy, scanning electron microscopy and a dissolution method. A new salt consisting of SQVM and SDS was crystallized and its crystal structure was elucidated and reported herein for the first time. The anionic part of SDS interacts with the cationic segment of SQVM to obtain a new salt designated as SQV-DS, which precipitates. The main difference between the two structures occurs in the c-axis expansion, which increases from 15.966 (5) to 21.1924 (14), respectively. Some of the strategies to enhance the dissolution rate of poorly aqueous soluble APIs include the use of surfactants such as SDS in the dissolution medium, as well as in the formulated products. However, there have been constant reports of a dissolution rate slowdown by some surfactants. The interaction mechanisms between the APIs and the dissolution medium containing surfactants need to be carefully investigated in current pharmaceutical formulations. Graphical Abstract.

Comparative assessment of environmental parameters of foaming agents based on synthetic hydrocarbon used for extinguishing the fires of oil and petroleum products

The paper examines in detail the environmental impact of foaming agents used for extinguishing Class B fires, which include oil and petroleum product fires. There is a significant negative impact on the environment of long-chain fluorine-containing foaming agents and the search for alternatives of their use for firefighting. The advantages of calculation methods for determining the environmental parameters of foaming agents to extinguish fires, taking into account their chemical structure, are noted. The method «Quantitative Structure - Property Relationships» was used for obtaining BCF, LC50 (Fathead Minnow, Daphnia Magna), IGC50 (Tetrahymena Pyriformis) for a number of foaming agents with a carbon chain length C8-C14, containing fluorine and fluorine-free. It is shown that according to BCF the safest is sodium lauryl sulfate, according to LC50 (Daphnia Magna) the safest of the studied are foaming agents based on alkyl compounds Sodium decyl sulfate, Sodium lauryl sulphate, Triethanolamine salt of deсyl sulfate (third class of acute toxicity), whereas fluorine-containing compounds (6:2 fluorotelomers) according to LC50 (Daphnia Magna) belong to the first class of acute toxicity (the most dangerous of the studied compounds). Keywords: fluorine-free foaming agent; fluorotelomer; oil; petroleum products; extinguishing the fires; environmental parameter; calculation method.

Simultaneous adsorption of anionic alkyl sulfate surfactants onto alpha alumina particles: Experimental consideration and modeling

Simultaneous adsorption of four anionic alkyl sulfate (AS) surfactants, including sodium octyl sulfate, sodium decyl sulfate, sodium dodecyl sulfate and sodium tetradecyl sulfate named as C8, C10, C12 and C14, onto alpha alumina (α-Al2O3) particles were systematically investigated. Concentrations of all mixtures of anionic AS surfactants in aqueous solution were quantified by capillary electrophoresis coupled with contactless conductivity detection (CE-C4D). Adsorption isotherms of the four anionic AS surfactant homologs increased with either the decrease of pH from 6.0 to 4.0 due to enhancement of electrostatic attractions between the positively charged α-Al2O3 surface and the anionic AS surfactants or the increase of carbon chain length due to enhanced hydrophobic interactions. At different salt concentrations, a common intersection point (CIP) obtained for adsorption isotherms demonstrated that the contributions of electrostatic and hydrophobic interactions were reversed. The ionic strength effect on anionic AS surfactant adsorption isotherms onto α-Al2O3 particles was thoroughly studied. Simultaneous adsorption of the four AS surfactants onto the α-Al2O3was controlled by both electrostatic and hydrophobic interactions that were in accordance with Langmuir and two-step models.

Effect of micelles on pKa* of acridine: a spectroscopic study

The effect of anionic, nonionic and cationic surfactants on the protonation reaction of acridine in an excited state has been studied. In the case of sodium decyl sulfate and sodium dodecyl sulfate, the observed shift in pK * to a more alkaline region was +0.6 and +0.9 units (from 9.9 to 10.5 and 10.8 respectively), which corresponds to a decrease in the Gibbs free energy by 3.5 and 5.0 kJ mol–1.

Removal of period 4 transition metals by foam separation

Anionic surfactants that form floating bubbles can adsorb metal ions and change foams at the gas–liquid interface. The final rate of ion removal by foam separation determines the selectivity or priority of adsorption of ions. Foam separation was conducted to remove multi-component chlorides of period 4 transition metals (Mn, Fe, Co, Ni, Cu, and Zn) by using sodium decyl sulfate (SDeS) and sodium dodecyl sulfate (SDS) as surfactants. The first-order ion-removal rate constant (k) did not completely change with an increase the atomic number of transition metals. The difference in removal rate constant (k) between the elements was not significant in multi-component chlorides of transition metals. On the other hand, the foam separation was performed in a one-component of period 4 transition metal (Mn, Fe, Co, Ni, Cu, and Zn) using SDeS (8 mmol L−1) for comparing k from alkaline earth metals having different ionic radii, respectively. The transition metal was continuously removed over time, whereas the counter ion (sodium) of the surfactant was not efficiently removed. The results also showed that the k in the one-component 4 transition metal system also slightly increased with increasing ionic radius in 5 h of foam separation. A linear relationship was observed between the first-order ion-removal rate constant (k) by foam separation and the ionic radius of the divalent metal ion. These results indicated that the selectivity of cation adsorption on the soluble monolayer is closely related to the ionic radius of the metal ion.

Abnormal behaviors in the calibration curves of liquid chromatography-tandem mass spectrometry occurring in the quantitative analysis of surfactants near critical micelle concentrations.

Surfactants, including quaternary ammonium compounds, are widely used in daily life as part of consumer chemical products and, more recently, in the shale oil industry. Because of their unique amphiphilic properties, surfactants form micelles at concentrations above a certain threshold known as the critical micelle concentration (CMC). A previous electrospray ionization mass spectrometry studies conducted by Siuzdak et al. and others presented indirect evidence regarding micelle formation. Herein, we have used liquid chromatography-tandem mass spectrometry to explore how such micelle formations affect the quantitative analysis of surfactants. Results reveal abnormal behaviors in the calibration plots of a few selected anionic and cationic surfactants, such as sodium decyl sulfate (SDeS), sodium dodecyl sulfate (SDS), myristyltrimethylammonium bromide (MTAB), and benzyldimethyloctadecylammonium chloride (BAC-18). At concentrations close to the respective CMCs of these surfactants, the calibration plot for MTAB flattened, whereas the slopes of the calibration plots for SDeS, SDS, and BAC-18 suddenly changed. These abnormal behaviors can be related to micelle formation. From a practical perspective, the above observations suggest that in the quantitative analysis of surfactants, high micelle concentrations close to the CMC should be avoided to obtain accurate surfactant measurements.

Temperature Dependence of Micellization Properties of Binary Mixtures of Sodium Decylsulphate with Sodium Dodecylsulphate in Water

Conductance measurement method has been used to determine the critical micelle concentration (CMC) and counterion binding constant values of binary mixtures of sodium decylsulphate (SDeS) with sodium dodecylsulphate (SDS) in water at four different temperatures ranging from 298 K to 313 K at 5 K intervals. Rubingh′s model has been used to calculate the mixed micellization properties viz. mixed micelle composition, activity coefficient of the components, and mutual interaction parameter between the components. Variation of these mixed micellization properties with temperature has been studied. The studied binary surfactant mixtures show attractive interaction between the components and it decreases with increase in temperature, which is an interesting trend. Thermodynamic parameters of mixed micellization have also been calculated. The enthalpy (ΔH°mic) and entropy (ΔS°mic) of micellization compensate each other.

Вплив децилсульфату натрію та хлорпромазину на постгіпертонічний шок еритроцитів ссавців

Вплив децилсульфату натрію та хлорпромазину на постгіпертонічний шок еритроцитів ссавців

A Generalized Theoretical Model for the Relationship Between Critical Micelle Concentrations, Pressure, and Temperature for Surfactants

AbstractDirectional solvent extraction (DSE) has been gaining interest as a water treatment technology in recent years. DSE utilizes the process of micellization for the purposes of species separation between water and complex chemical systems. In this article, we develop a conformal geometric algebra‐based formulation that models surfactants, their solubilities, and critical micelle concentration (CMC), with relation to temperature and pressure. Molecules are represented as spatially distributed networks embedded in R4,1 space, and the mathematical characterizations of these molecules are shown to be effective in modelling CMC as a function of temperature and pressure. One of the contributions of this work is the utilization of this formulation to develop a governing expression, in the form of a three‐dimensional relationship, between CMC, pressure, and temperature for a general surfactant. In prior works, the CMC–temperature plane and CMC–pressure plane expressions have been extensively documented for sodium alkyl sulfates. In this work, we extend the formulation to model the CMC of decanoic acid, sodium octyl sulfate, sodium decyl sulfate, sodium dodecyl sulfate, and sodium tetradecyl sulfate. Using this theoretical model, a relationship between CMC and the directional solubility of water in a surfactant is determined. Directional solubility is related to temperature and pressure, and on this basis, we devise a directional solubility–pressure–temperature expression for an arbitrary surfactant to improve the state of the art for DSE. From this expression, we propose a novel isothermal DSE process for water treatment.

Application of foam separation method for removal of alkaline earth metal ions from solution

Foam separation was used to separate dissolved alkaline earth metal ions from aqueous solution. The mechanism is based on anionic surfactant adsorption onto the bubbles generated in the aqueous alkaline earth metal solution. The negatively charged bubbles rise while adsorbing the positive metal ions and change to foam at the surface. The foam in the glass tube drains excess water as it rises and is finally turned into dry foam. The foam separation method with sodium decyl sulfate (SDeS) (8 mmol L−1, below the critical micelle concentration (CMC)) was used to remove alkaline earth metal (Mg, Ca, and Sr) chlorides in the respective systems. The initial concentrations of the surfactant and alkaline earth metal chloride were 8 mmol L−1 (below the CMC) and 2.5 mmol L−1 in 250 mL of solution, respectively. The results showed that the removal rate in the one-component alkaline earth metal system increased with increasing atomic number: Mg (46%) < Ca (58%) < Sr (77%) in 5 h of foam separation. A similar trend was observed in the foam separation in a mixed system of alkaline earth metals. However, the concentration of the surfactant counterion (Na+) remained almost constant after the operation, indicating that the divalent ions, rather than the monovalent surfactant counterions, were preferentially adsorbed onto the sulfate group of the anionic surfactant. The changes in the concentration of the alkaline earth metal ions were analyzed using kinetics. The plot of the first-order rate constant against the ionic radius of each metal suggested a linear relationship in each series of alkaline earth metals or alkali metals. The present study indicates that foam separation using SDeS can be used to effectively remove large alkaline earth metal ions from contaminated water.

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.