Investigation of the impacts of simple electrolytes and hydrotrope on the interaction of ceftriaxone sodium with cetylpyridinium chloride at numerous study temperatures

The current research work centred on the micellization of binary system of Cetylpyridinium chloride (CpyCl) and cetyltrimethylammonium bromide (CTABr) in the absence and presence of nonionic hydrotropes (i.e urea and resorcinol) using conductometric technique. The critical micelle concentrations (CMC), at different mixed mole fraction of mixed surfactant were evaluated. Activity coefficient, ideal CMC, micellar mole fraction, interaction and thermodynamic parameters were obtained using theoretical Clint and Rubingh models.Addition of hydrotropes lowered the CMC values than the ideal CMC values and the individual components which is an indication of positive synergistic interaction in CpyCl/CTABr mixed micelle formation. The interaction parameter values were all negative, signifying strong interaction between the mixed surfactant. The evaluated thermodynamic parameters were all negative, indicating spontaneity and stability of the mixed micelle formed.

Micelle formation and physico-chemical variables for the sodium dodecyl sulfate/cetylpyridinium chloride and their mixture in aqueous propranolol hydrochloride drug solvent: Conductivity and theoretical analysis

Herein, the conductivity measurement technique is used to determine the interactions that may occur between polyvinyl pyrrolidone (PVP) polymer and cetylpyridinium chloride (CPC) surfactant in the presence of NaCl and Na2SO4 of fixed concentration at variable temperatures (298.15–323.15 K) with an interval of 5 K. In the absence or presence of salts, we observed three critical micelle concentrations (CMC) for the CPC + PVP mixture. In all situations, CMC1 values of CPC + PVP system were found to be higher in water than in attendance of salts (NaCl and Na2SO4). Temperature and additives have the tendency to affect counterion binding values. Various physico-chemical parameters were analyzed and demonstrated smoothly, including free energy (ΔG0m), enthalpy (ΔH0m) and entropy change (ΔS0m). The micellization process is achieved to be spontaneous based on the obtained negative ΔG0m values. The linearity of the and values is excellent. The intrinsic enthalpy gain (ΔH0*m) and compensation temperature (Tc) were calculated and discussed with logical points. Interactions of polymer hydrophobic chains or the polymer + surfactant associated with amphiphilic surface-active drugs can employ a strong impact on the behavior of the gels.

Effects of inorganic electrolytes and of pH on micelle formation of amphoteric-anionic mixed surfactant systems

Predicting the behaviour of solutions with surfactants of significantly different critical micelle concentration (CMC) values remains a challenge. The study of the molecular interactions within micelles and interfaces in surfactant combinations used in everyday products is essential to understand these complex systems. In this work, the equilibrium and dynamic surface tension in the presence of mixed non-ionic (tristyrylphenol ethoxylates) and anionic (sodium benzene sulfonate with alkyl chain lengths of C10-C13) surfactants, commonly encountered as delivery systems in agrochemicals, were studied and their CMC values were determined. For the surfactant mixtures, four molar ratios were examined: nEOT/nNaDDBS = 0.01, 0.1, 1, 4 and two different cases were analysed, the premixed and the add one by one surfactant. The surface tension for single surfactants stabilised quickly, while the mixtures needed a long time to reach equilibrium; up to 15 h for the premixed mixtures and 40 min when surfactants were added one by one. The CMC values for the nEOT/nNaDDBS = 0.01, 0.1 premixed surfactant mixtures were found to be in between the CMC values of the single surfactants, but those for the nEOT/nNaDDBS = 1 and 4 mixtures were lower than the CMCs of both single surfactants. Calculations based on the regular solution theory suggested that there are attractive forces in the mixed micelles and at the interface layers, while the supramolecular assemblies in the bulk (i.e., micelles) and at interfaces (surfactant films) are preferentially enriched in EOT.

We studied the influence of cationic hydrotrope aniline hydrochloride on the micellization behavior of cationic amphiphilic phenothiazine drug promazine hydrochloride in the presence and absence of 50mmol kg−1 NaCl. The experimental critical micelle concentration (CMC) values came out to be lower than ideal CMC (CMC id ) values, signifying attractive interactions between the two components in mixed micelles. NaCl further decreases the CMC of pure PMZ and aniline hydrochloride as well as their mixture due to screening of the electrostatic repulsion among the polar head groups. The bulk properties of solution were examined by using different theoretical models for justification and comparison of results. The micellar mole fraction of aniline hydrochloride (X1 Rub , X1 M , X1 Rod and X1 id ) was evaluated by different proposed models, showing greater contribution of hydrotrope in mixed micelle. The negative values of interaction parameter (β) indicate synergistic interactions and negative values of β further decrease by the addition of salt in mixed systems. From the CMC values as a function of temperature, various thermodynamic properties have been evaluated and discussed in detail.

New dimeric surfactants [16‐s‐16, s: (CH2)4; CH2–COO–(CH2)2–OCO–CH2; CH2–COO–ISO–OCO–CH2 (ISO = d‐isorbide) and CH2–CONH–(CH2)2–NHCO–CH2] were synthesized and characterized (I–IV, respectively). The micellization behavior of dimeric surfactants with various spacers was studied by conductance/steady‐state fluorescence quenching (SSFQ) measurement and compared with the conventional surfactant (cetyltrimethylammoniumbromide, CTAB). The critical micelle concentration (CMC) values of several surfactants were found to be nearly the same by both techniques. Conductance measurements were used exclusively to obtain CMC and degree of dissociation (α) values at various temperatures, while SSFQ measurements were used to obtain a few CMC values (for comparison) and an aggregation number (Nagg). A decrease in CMC and Nagg values and an increase in α were observed for dimeric surfactants when compared with CTAB. CMC decreases and then increases with a continuous increase in temperature (U‐shaped behavior). The temperature of minimum CMC, Tm, was distinctly different for CTAB and the dimeric surfactants. Tm values were dependent on the nature of the spacer. The temperature dependence of CMC and α value was used to calculate the thermodynamic parameters of micelle formation for two classes of surfactant (conventional and dimeric). Enthalpy‐entropy compensation plots exhibited fair linearity except for IV. Compensation lines for spacers containing ester groups are parallel to one another. Micro‐polarity and apparent dielectric constant (εa) data suggest that the micellar environment felt by pyrene is similar to that of an alkanol with a 3–4 carbon chain.

Solubilization of aqueous-insoluble phenothiazine drug in TX-100 micellar solution and interactions of cationic/anionic surfactants with phenothiazine–TX-100 system

The micellization and surface activity properties of long-chain pyridinium ionic liquids n-alkyl-3-methylpyridinium bromide ([Cnmpy][Br], n: the carbon numbers of hydrophobic tails, n = 12, 14, 16) in aqueous solution were systematically investigated through electronic conductivity measurement, surface tension, and ultraviolet-absorption spectra. The surface chemical parameters and thermodynamics parameters were obtained. The [Cnmpy][Br] ionic liquids exhibit higher surface activities than conventional surfactants with corresponding alkyl chain lengths. The effects of inorganic salts (LiBr, NaBr, MgBr2), organic alcohols (C2H5OH, C3H7OH, C4H9OH, C5H11OH) and temperature on the critical micelle concentration (CMC) values of [Cnmpy][Br] aqueous solutions were also investigated. The CMC values remarkably decreased with the addition of inorganic salts. The CMC values increased slightly in the presence of ethanol, but decreased gradually as the chain length of the alcohol increased. The CMC values assumed a trend of decreasing and then increasing with the increase of temperature. The calculation results of thermodynamic parameters show that both adsorption and micellization processes of [Cnmpy][Br] are spontaneous; the enthalpy of [C12mpy][Br] is negative at 293.15 K and becomes negative with temperature increasing. For [C14mpy][Br] and [C16mpy][Br] this transition occurs at 288.15 K and the micellization process is entropy-driven in the investigated temperature range.

Micellization pattern of cationic surfactants in presence of azo dye in methanol mixed media

The uncontrolled distribution of surfactants which are commonly used as household and industrial products like soaps, lubricants and detergents in the global market have provoked this study. The determination of critical micelle concentration (CMC) of glycerol monostearate surfactant (GMS) was evaluated using Conductivity and UV-Visible Spectroscopic techniques respectively. The effect of solubility was quantified and the Krafft temperature was obtained. The thermodynamic feasibility parameters were evaluated using Erying and Vant Hoff’s equations. The CMC values were taken from the sharp breaks in the plots of absorbance versus surfactant concentrations and conductivity versus surfactant concentration respectively. The result showed that as the temperature increases, the CMC initially decreases and then followed by slight increase owing to the smaller probability of hydrogen bond formation at higher temperatures. The result showed that the critical micelle concentration of GMS obtained using Conductivity and UV-Visible techniques were 4.50 × 10-2 and 2.40 × 10-2 moldm-3 respectively and the Krafft temperature (KT) was obtained at 50°C. The Gibbs free energy change of micellization (ΔG° CMC) was found to decrease as temperature increases over the whole temperature range. The entropy change of micellization (ΔS° (CMC)) showed positive values throughout the temperature range tested while the large enthalpy change, ΔH° (CMC) means that in the micellization process, the attractive interaction among hydrophobic chains was opposed by the strong interaction of the oxyethylene chains of glycerol monostearate with water molecules. The study revealed that the use of UV-Visible Spectroscopy technique was a very good and easy way of determining the critical micelle concentration of GMS. This study is also a valuable industrial tool for the production of soap related products and its applications in domestic and industrial processes.

The interfacial and micellization behavior of three dicarboxylic amino acid-based anionic surfactants, abbreviated as AAS (N-dodecyl derivative of -aminomalonate, -aspartate, and -glutamate) in combination with hexadecyltrimethylammonium bromide (HTAB) were investigated by surface tension, conductance, UV-vis absorption/emission spectroscopy, dynamic light scattering (DLS), and viscosity studies. Critical micelle concentration (CMC) values of the surfactant mixtures are significantly lower than the predicted values, indicating associative interaction between the components. Surface excess, limiting molecular area, surface pressure at the CMC, and Gibbs free energy indicate spontaneity of the micellization processes compared to the pure components. CMC values were also determined from the sigmoidal variation in the plot of micellar polarity and pyrene UV-vis absorption/emission intensities with surfactant concentration. The aggregation number, determined by static fluorescence quenching method, increases with decreasing mole fraction of the AAS (αAAS), where the micelles are mainly dominated by the HTAB molecules. The size of the micelle increases with decreasing αAAS, leading to the formation of larger and complex aggregates, as also supported by the viscosity studies. Micelles comprising 20-40 mol % AAS are highly viscous, in consonance with their sizes. Some of the mixed surfactant systems show unusual viscosity (shear thickening and increased viscosity with increasing temperature). Such mixed surfactant systems are considered to have potential in gel-based drug delivery and nanoparticle synthesis.

The synthesis of quaternary N-alkyl tropinium cationic surfactants and study on their properties: effect of temperature, hydrophobic chain length and anions

Three cationic surfactants labeled as APS-8 ((Z)-4-(((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N,N-dimethyl-N-octylbenzenaminium bromide), APS-12 ((E)-4-(((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N-dodecyl-N,N-dimethylbenzenaminiumbromide), and APS-16 ((E)-4-(((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N-dodecyl-N,N-dimethylbenzenaminium bromide) were opportunely synthesized in order to study the effect of the hydrocarbon chain length on the process of micellization in mixed surfactant systems. The critical micelle concentration (CMC) values of binary mixtures containing APS-x (x = 8, 12, 16) and a conventional cationic surfactant (cetyltrimethylammonium bromide, CTAB) were retrieved by using surface tension measurements. The behavior of the mixed systems has been analyzed in the light of Rubingh’s regular solution theory. In particular, two parameters describing respectively the interactions at the air/water interface and in the micellar phase were obtained for each system. Results show that micellization and adsorption properties of the mixed systems depend on the hydrophobic chain length and on the interaction of APS-x with CTAB. Furthermore, applying the regular solution theory (RST) to the experimental data allowed obtaining the interaction parameter of the mixed micelles (β) and the air–water interface (βσ). Results indicate an attractive interaction between the micelles and reveal a synergistic effect between the two components of the mixtures both in micelles and at the interface. The activity coefficients and the experimental CMC values in micelles indicate synergism less than as well as at the interface.

Application of inhibitors is an established and cost-effective method to mitigate internal corrosion of mild steel pipelines in the oil and gas industry. Conventionally, surfactant-type organic inhibitors are frequently applied based on their critical micelle concentration (CMC) values and their adsorption to mild steel evaluated based on laboratory tests that show a reduction in corrosion rate. In this work, the relationship between reduction in corrosion rate, CMC and inhibitor surface saturation concentration on mild steel was studied using model quaternary ammonium inhibitors with different alkyl tail lengths. The quaternary ammonium model compounds were synthesized in-house and characterized by 1H-NMR before their use. Their CMCs were determined using surface tension measurements. Results showed that, although the CMC value and surface saturation concentration were the same for two of the inhibitors tested, there was no relationship observed between measured CMC values, surface saturation concentrations, and the calculated corrosion efficiencies for the five model inhibitor compounds tested. Consequently, using CMC values as a measurement for injection of inhibitors might not be considered as a reliable factor.