Effect of Sodium Dodecylbenzenesulfonate on the Association Behavior of Promethazine Hydrochloride in Aqueous/Electrolyte Solutions at Different Temperatures

The interaction between the amphiphilic phenothiazine drug promethazine hydrochloride (PMT) and an anionic surfactant sodium dodecylbenzenesulfonate has been investigated using the conductometric technique in the absence and presence of an inorganic salt (50 mmol·kg^?1 NaCl) at five different compositions and temperatures. PMT is employed for the cure of allergic symptoms. Different physicochemical parameters such as critical micellar concentration (cmc), thermodynamic, and micellar composition are evaluated and discussed in detail using regular solution theory (RST). The addition of salt decreased the surface charge of micelles, lowering the cmc values of the amphiphile. The interaction parameter (β) is negative at all temperatures and compositions indicating attractive interactions. Due to the presence of NaCl in mixed systems the attractive interaction (β) was further increased (β values more negative). The negative values of Gibbs energy (\( \Delta G^{0}_{\text{m}} \)) of mixing revealed the stability of the solution. Owing to the presence of NaCl, the \( \Delta G^{0}_{\text{m}} \) values are found to be more negative suggesting that the driving force for interaction was significantly increased and micellization more thermodynamically favorable.     

Synthesis and properties of quaternary ammonium Gemini surfactants with hydroxyl groups

The article describes synthesis of four hydroxyethyl alkylene–double alkyl bromide through substitution of nucleophilic d iethanolamine, 1-bromododecane, and 1,4-dibromobutane. The structure of the new hydroxyl cationic surfactant (HDCS) was characterized by ¹H NMR and FTIR spectra. The aqueous solution of HDCS showed critical micelle concentration, i.e., 5.6 × 10^?2 mM, and could reduce oil/water interfacial tension to 3.28 × 10^?3 mN m^?1. The surface tension measurements provided a series of parameters, including critical micelle concentration (CMC), surface tension at the CMC (γ_CMC), adsorption efficiency (pC₂₀), and effectiveness of surface tension reduction (Π_CMC). In addition, maximum surface excess concentration (Г_max) and minimum surface area/molecule (A_min) at the air/water interface were obtained by the Gibbs adsorption isotherm. The influence of inorganic salts (sodium chloride, calcium chloride) and organic salts (sodium benzoate) on the surface tension of HDCS in aqueous solution was investigated. For wettability alteration measurement, contact angle measurement as a quantitative method was utilized. Meanwhile, foam ability, foam stability, and emulsifying property of the synthesized surfactant were also examined at different concentration. HDCS also had excellent viscosity property.     

Interaction Between an Active Pharmaceutical Ingredient Ionic Liquid Benzalkonium Salicylate and Small Biomolecules in Aqueous Solution: UV Absorption,Conductivity, and Volumetric Study

UV absorption spectroscopy, electrical conductivity and density experiments have been used to investigate the interactions of some small biomolecules (amino acids/dipeptides) with an active pharmaceutical ingredient in ionic liquid form (API-IL), benzalkonium salicylate (BaSal), in aqueous solution. A number of useful parameters, such as critical micellar concentration (cmc), aggregation number (N_agg) and limiting molar conductivity (Λ₀) of BaSal, standard partial molar volumes (\(V_{2,\phi }^{ \circ }\)), corresponding volumes of transfer from water to aqueous BaSal solutions (Δ_trV^o), standard partial molar expansibilities (\(E_{\phi }^{ \circ }\)), hydration number (n_H) of small biomolecules, as well as the binding constants (K_b) for small biomolecule–BaSal complexes have been evaluated. The dependence of the properties on concentration, temperature and alkyl chain length of amino acids/dipeptides is examined. The results are used to identify the solute–solvent physicochemical interactions occurring in the studied systems.     

Solubilization of Magnesium Octa[(4′-Benzo-15-Crown-5)Oxy]Phthalocyaninate in Aqueous Micellar Solutions of Hexadecyltriphenylphosphonium Bromide

Electronic absorption spectroscopy and fluorimetry have been employed to study the behavior of magnesium octa[(4′-benzo-15-crown-5)oxy]phthalocyaninate (Mg[(B15C5O)₈Pc]) in aqueous micellar solutions of sodium dodecyl sulfate and hexadecyltriphenylphosphonium bromide. Conditions have been found for the existence of monomeric Mg[(B15C5O)₈Pc] complex in surfactant solutions to provide the possibility of using mixed solutions of the complex and cationic surfactants (alkyltriphenylphosphonium bromides) for photodynamic therapy. In surfactant solutions with different concentrations of micelles (c_m) and the complex (c_p), the maximum amount of monomeric Mg[(B15C5O)₈Pc] is achieved at c_m/c_p ≥ 4.     

Physicochemical Properties of Aqueous Solutions of Binary Mixtures of Lignin Derivatives and Sodium Dodecyl Sulfate

Physicochemical properties of aqueous solutions of binary mixtures of lignosulfonates and sodium dodecyl sulfate were studied. Introduction of sodium dodecyl sulfate into solutions of high-molecular-mass lignosulfonates at certain ratios causes macrophase separation of the systems with the formation of loose precipitates. A synergistic effect of a decrease in the surface tension is observed in the mixed solutions. This effect increases with increasing lignosulfonate molecular mass and temperature. The revealed relationships are caused by hydrophobic interactions of hydrocarbon radicals of sodium dodecyl sulfate with hydrophobic segments of lignosulfonate polymer chains with the formation of micellar associates. Aqueous solutions of binary mixtures of lignosulfonates (с_LS ≥ 0.2 g dm^–3) and sodium dodecyl sulfate (с_DSNa ≥ 0.08 g dm^–3) can be recommended for use as surfactant formulations for high-temperature autoclave leaching of polymetal ores.     

Electrical percolation in micellar sodium dodecyl sulfate solutions. a phenomenological consideration

Effects of electrical percolation accompanying variations in overall surfactant concentration с have been studied by the example of micellar sodium dodecyl sulfate solutions. It has been found that, in the studied concentration range of 0.001–1.2 M, dependences of electrical conductivity K on c may exhibit at least three break points, with the dK/dc derivatives changing in the vicinities of these points. At two of these points, which are reliably identified and correspond to critical micelle concentrations (CMC₁ and CMC₂), they decrease. At the third concentration, lying between CMC₁ and CMC₂, the dK/dc derivative increases. A substantiated assumption has been put forward that this break point, at which the dK/dc derivative increases, results from the clustering of micelles and the appearance of channels with a higher specific conductivity, which is provided by the contribution from the electrical conductivity of the diffuse and dense parts of micelle electrical double layers, upon the formation of clusters. The ionic surfactant concentration that corresponds to the break point at which the dK/dc value increases has been denoted as the critical percolation concentration.     

Protolytic properties of <Emphasis Type="Italic">DL</Emphasis>-alanyl-<Emphasis Type="Italic">DL</Emphasis>-methionine and its complexation in aqueous solutions and micellar solutions

Dissociation constants of DL-alanyl-DL-methionine have been determined in water and micellar solutions of surfactants (anionic sodium n-dodecyl sulfate, cationic cetylpyridinium chloride, and nonionic Brij 35). It has been established that CuA⁺ and CuH_–1A complexes are formed in water and micellar solutions of sodium n-dodecyl sulfate, while CuA⁺, CuH_–1A, and Cu_–2A^– complexes are formed in micellar solutions of cetylpyridinium chloride and Brij 35. Stability of the complexes depends on micelle surface charge and degrees of binding of individual chemical forms by a micellar pseudophase.     

The Effect of a Cationic Gemini Surfactant,Ethonium, on the Physicochemical Properties of Quercetin in Solutions and on the Surface of Highly Dispersed Silica

The formation of supramolecular complexes with ethonium, a cationic gemini surfactant having a broad-spectrum antimicrobial activity, is shown to significantly alter the physicochemical properties (spectral, protolytic, and adsorption properties and solubility) of a natural f lavonol, quercetin. The constant of binding between quercetin and ethonium is calculated. Apparent dissociation constants pK _a1 ^a of quercetin in solutions of this cationic surfactant are for the first time determined within a broad concentration range. A shift in the pH dependence of quercetin adsorption by 0.5 units to the alkaline region upon the transition from a premicellar ethonium solution to a micellar one correlates with an increase in pK _a1 ^a under these conditions. The value of quercetin adsorption from aqueous ethonium solutions depends on the concentration of the cationic surfactant, pH of a solution, and the pK _a1 ^a value of the f lavonol bound into the supramolecular complex.     

Surface and micellar properties of some amphiphilic drugs in various salt solutions

In this work the effect adding of various electrolytes on the solution properties of three amphiphilic drugs was investigated. The critical micelle concentration (cmc) values, determined on the basis of surface tension measurements, were found to decrease with the increasing salt concentration; this decrease was dependent upon the nature of added ion. Coions (K⁺ and Na⁺) remained in the aqueous phase and were almost equally efficient in decreasing the cmc. Counterions (Cl^? and Br^?) concentrated on the micellar surface and reduced electrostatic repulsion. The smaller the hydrated counterions, the stronger they interacted with the micellar surface. The decrease of cmc was therefore more pronounced for Br^? ions than that for Cl^? ones. The observed changes in A _min and Γ_max were explained in terms of the cmc behavior. The values of both ΔG _m ^pO and ΔG _ads ^pO suggest that the drugs tend to form micelles more readily in the presence of salts.     

Interactions Between Surface Active Ionic Liquid and Procaine Hydrochloride Drug in Aqueous Solution

Complex formation between the anesthetic drug, procaine hydrochloride and a surface active ionic liquid (SAIL), 1-tetradecyl-3-methylimidazolium chloride, [C₁₄mim][Cl], in aqueous medium has been investigated using surface tension, fluorescence and DLS measurements at 298.15 K and conductance at 288.15, 298.15 and 308.15 K. Critical aggregation concentration (CAC), degree of ionization (α), and various thermodynamic parameters were determined using the conductivity measurements. The interfacial behavior of SAIL at different concentrations of the drug was evaluated from surface tension measurements by calculating a series of surface parameters and CAC values. Fluorescence spectroscopy was used to evaluate the binding constant (K) and the standard state Gibbs energy change (ΔG°) for the formation of drug–SAIL complexes, which confirms the existence of cation–π interactions between the drug molecules and imidazolium ring of the SAIL molecules. The CAC values were found to decrease with increase in the concentration of the drug, which is due to the balancing between hydrophobic and electrostatic interactions. Dynamic light scattering provides sufficient information about the size of the aggregates and the variation in the hydrodynamic diameters pertaining to the changes in the drug concentration. The results from above methods show that the aggregation process of SAIL is favored by increases in the concentration of the drug. It is demonstrated that with the better understanding of the interactions, [C₁₄mim][Cl] can be judiciously utilized in making use of procaine hydrochloride.     

Concentration,temperature, and isotopy effects on the heat capacity of aqueous urea

Relations for the apparent molar heat capacity ?_c of urea in an aqueous solution depending on the molality m and temperature were obtained. A transition to the relations ?_c(m,T) for D₂O-(ND₂)₂CO and T₂O-(NT₂)₂CO systems was effected by temperature scaling. At low temperatures, the isotherms of the molar heat capacity C _p(m) of the protium and deuterium systems have minima shifted to more dilute solutions at elevated temperatures. At m = 1, C _p of a solution does not depend on temperature in both systems. The dependences C _p(T) also have minima at constant concentrations. The temperature of the minimum heat capacity is most effectively lowered by small additions of urea. For m = 0.25, T _min is 7.5 K lower than T _min of pure water, and its heat capacity is 0.08 J/(mol K) higher. A transition from m = 1.5 to m = 2 lowers the temperature of the minimum heat capacity by 3.6 K; thus, the heat capacity of solutions differs by 0.02 J/(mol K) only.     

Thermodynamic characteristics of the dissolution of glycine,glycylglycine, and glycylglycylglycine in aqueous solutions of sodium dodecyl sulfate at <Emphasis Type="Italic">Т</Emphasis> = 298.15 K

the enthalpies of dissolution of glycine (Gly), glycylglycine (GlyGly), and glycylglycylglycine (GlyGlyGly) are measured in aqueous solutions of sodium dodecyl sulfate (SDS) at SDS concentrations m = 0–0.7 mol kg^?1 and Т = 298.15 K by means of calorimetry. The obtained data are used to calculate the standard values of enthalpies of dissolution (Δ_sol H ^m ) and enthalpies of transfer (Δ_tr H ^m ) of glycine and its oligomers from water to SDS aqueous solutions. The dependences of Δ_sol H ^m and Δ_tr H ^m on SDS concentration in an aqueous solution at a constant concentration of glycine and its oligomers are determined. A comparative analysis of the thermodynamic characteristics of Gly, GlyGly, and GlyGlyGly transfer within the studied range of SDS concentrations is performed. The results are interpreted in terms of ion–ion, ion–polar, and hydrophobic interactions between SDS and molecules of glycine and its oligomers.     

Dissolution kinetics of silver metal nanoparticles in their reaction with nitric acid in an reverse micelle solution of AOT

The dissolution of silver nanoparticles in their reaction with aqueous HNO₃ solubilized to an reverse micelle solution of sodium bis(2-ethylhexyl)sulfosuccinate in decane is studied spectrophotometrically. A physicochemical model is advanced for quantifying the process kinetics on th basis of the following autocatalytic scheme: Ag⁰ + H⁺ + NO ₃ ^? → Ag⁺ + products (k ₁), and Ag⁰ + Ag⁺ + NO ₃ ^? → 2Ag⁺ + products (k ₂). The effective rate constant k ₂ decreases with decreasing solubilization capacity V _S/V _O (where V _S is the volume of the solubilized dispersed aqueous phase and V _O is the volume of the micelle solution); the solubilization capacity determines the size of the micelle cavities in which the reaction between Ag⁰ and HNO₃ occurs: k ₂ = 74 (V _S/V _O) · 100% ≈ 3.8%), 41 (2.9), and 35 (2.0) L/(mol s). The effective constant k ₁ is determined with a high uncertainty; the effect of V _S/V _O on k ₁ has the opposite tendency.     

Determination of the Water/AOT/Isooctane Reverse Micelles Size Parameters from Their Refractive Index Data

The present paper aims to study the proprieties of water confined in water/AOT/isooctane reverse micelles from their refractive indices at 298.5 K. The refractive indices of the microemulsions were investigated at increasing water concentration and at different micellar volume fractions, Φ _d. The refractive index of micellar water was deduced for a large water to AOT molar ratio, W ₀. The refractive index of interfacial water was also calculated. Then, the molar faction of interfacial water, α, was deduced for different W ₀ values and compared with those measured by NMR as reported in the literature. The results show qualitative agreement. Finally, the average aggregation number, n _agg, the area per surfactant headgroup, σ, as well as the interfacial thickness, d _i, of the reverse micelles were determined for the W ₀ values studied. The values of these structural parameters also show good qualitative agreement with NMR and small angle X-ray scattering data reported in the literature. Thus, the refractive index method can be a cheap and fast alternative for these two methods.     

Synthesis of oligosiloxanes with 3-aminopropyl groups and their testing as surfactants in the preparation of polymer microspheres

Polydimethyl-co-methyl(3-aminopropyl)siloxanes differing in the content of amino groups and molecular weight were synthesized by two pathways, namely, by hydrosilylation of oligodimethyl-co-methylhydrоsiloxane with N-(trimethylsilyl)allylamine (TMSAA) and by copolymerization of octamethylcyclotetrasiloxane with methyl(3-aminopropyl)cyclosiloxanes. The colloid-chemical properties of the synthesized oligomers were studied. The oligosiloxanes possess high surface activity and can reduce the interfacial tension in the interface surfactant solution in toluene–water to 6.7–4.2 mJ m². Aggregatively stable polystyrene suspensions with particle of 0.5 and 0.8 μm in diameter were obtained in the presence of the synthesized oligomers.     

Thermochemistry of the Dissolution of Dipeptides Containing DL-α-Alanine in Aqueous Solutions of Sodium Dodecyl Sulfate at 298.15 K

Enthalpies of the dissolution of DL-α-alanylglycine (AlaGly), DL-α-alanyl-DL-α-alanine (AlaAla), DL-α-alanyl-DL-α-valine (AlaVal), and DL-α-alanyl-DL-norleucine (AlaNln) in an aqueous solution of sodium dodecyl sulfate (SDS) at SDS concentration of m = 0–0.07 mol kg^?1 and temperature Т = 298.15 K are measured via calorimetry. The standard values of the enthalpy of dissolution (Δ_solH ^m ) and the transfer of dipeptides (Δ_trH ^m ) from water to aqueous SDS solutions are calculated using the experimental data. The dependences of Δ_solH ^m and Δ_trH ^m the SDS concentration at a constant concentration of dipeptide are established. Thermochemical characteristics of the transfer of AlaGly, AlaAla, AlaVal, and AlaNln in the investigated range of SDS concentrations are compared. The results are interpreted by considering ion–ion, ion–polar, and hydrophobic–hydrophobic interactions between SDS and dipeptide molecules.     

Extensional rheology of cellulose/NaOH/urea/H<Subscript>2</Subscript>O solutions

The extensional flow behaviors of cellulose/NaOH/urea/H₂O solution were investigated by using capillary breakup extensional rheometry (CaBER). The effects of temperature, storage time and cellulose concentrations on both the storage modulus G′ and the loss modulus G″ were also analyzed. For 2 wt% cellulose solution, the G′, G″ and filament lifetime remained unchanged after long storage time. While, for 4 wt% cellulose solution, physical gels could form at either higher temperature or for longer storage time, and the filament lifetime, the relaxation time (λ _e ) and the initial extensional viscosity (η _e0) first increased and then decreased with increase of the storage time. The transition points of the filament lifetime shifted to lower storage time with the increase of the temperature. The η _e0 is proportional to λ _e . The results presented suggest that the extensional properties of the cellulose/NaOH/urea/H₂O solution first increase and then decrease during the gelation process, and the spinning time, which decreases linearly with the increase in the storage temperature, must be controlled below the time that η _e0 starts to decrease.