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An oleyl alcohol-based extended surfactant, sodium oleyl polyethylene oxide-polypropylene oxide sulfate (OE3P3S), was synthesized and identified using FT-IR and 1H NMR. The adsorption and aggregation behaviors of OE3P3S and its mixture with cationic surfactant alkyltrimethylammoniumbromide (ATAB) were investigated under different molar ratios. The static surface tension analysis indicated that the critical micellization concentration (cmc) and the critical surface tension (γcmc) of OE3P3S were 0.72 mmol/L, and 36.16 mN/m, respectively. The cmc and γcmc values of the binary system were much lower than that of the individual component. And the cmc values of OE3P3S/ATAB = 6:4 mixtures decreased with an increase in the chain length of the cationic surfactant in the binary system. It was found from the dynamic surface tension that there was a slower diffusion rate in the binary system compared to the pure surfactant, and the adsorption processes for OE3P3S/ATAB = 6:4 were mixed diffusion-kinetic adsorption mechanisms. With a combination of DLS data and TEM measurements, formations of vesicles in OE3P3S/ATAB = 6:4 solutions appeared to occur at a concentration of 0.05 mmol/L. By studying the formation of liquid crystal structures in an emulsion prepared with OE3P3S as the surfactant, it was found that the oil-in-water emulsion is birefringent with a Maltese cross texture, and the rheological properties revealed its predominant viscoelastic behavior and shear thinning properties. [ABSTRACT FROM AUTHOR]

The starting point for the preparation of polymeric membranes by phase inversion is having a thermodynamically stable solution. Ternary diagrams for the polymer, solvent, and non-solvent can predict this stability by identifying the phase separation and describing the thermodynamic behavior of the membrane formation process. Given the lack of data for the ternary system water (H2O)/hydrochloric acid (HCℓ)/polyamide 66 (PA66), this work employed the Flory–Huggins theory for the construction of the ternary diagrams (H2O/HCℓ/PA66 and H2O/formic acid (FA)/PA66) by comparing the experimental data with theoretical predictions. Pure polymer and the membranes produced by phase inversion were characterized to provide the information required to create the ternary diagrams. PA66/FA and PA66/HCℓ solutions were also evaluated regarding their classification as true solutions, and the universal quasi-chemical functional group activity coefficient (UNIFAC) method was used for determining non-solvent/solvent interaction parameters (g12). Swelling measurements determined the polymer/non-solvent interaction parameter (χ13) for H2O/PA66 and the solvent/polymer interaction parameter (χ23) for PA66/FA and PA66/HCℓ. The theoretical cloud point curve was calculated based on “Boom’s LCP Correlation” and compared to the curve of the experimental cloud point. The ternary Gibbs free energy of mixing and χ23 indicated FA as the best solvent for the PA66. However, for HCℓ, the lower concentration (37–38%), volatility, and fraction volume of dissolved PA66 (ϕ3) indicated that HCℓ is also adequate for PA66 solubilization based on the similar membrane morphology observed when compared to the PA66/FA membrane.

Polyvinylidene fluoride (PVDF) membrane has shown potential for CO2 capture due to their chemical stability and mechanical strength. The coating process using polypropylene (PP) influenced the CO2 flux. This study optimises the coating parameters on the PVDF membrane using Box-Behnken Design (BBD). Key factors examined were methyl ethyl ketone (MEK) concentration, operating time and coating cycles. The investigated PVDF membrane was employed in the membrane gas adsorption (MGA) to examine the CO2 flux. Experimental data were fitted to a second-order polynomial quadratic model, yielding an R² value of 0.9028, indicating a strong fit. The optimisation revealed that 25% MEK concentration, 30 min of operating time and single coating cycle obtained the highest desirability score of 0.945. Significant factors include the MEK concentration (p-value of 0.0228), operating time (p-value of 0.0018) and coating cycles (p-value of 0.0164). This model effectively captures the linear and interaction effects of the variable on the CO2 flux. The optimised parameters significantly enhance the CO2 flux, contributing to the development of a high-performance membrane for CO2 capture. The application of the optimised PVDF membrane in MGA system demonstrates its efficiency in CO2 separation. This study advances membrane technology, providing a robust framework for future research in CO2 separation. [ABSTRACT FROM AUTHOR]

The equilibrium and dynamic surface properties of anionic surfactant alcohol ether sulfate with different EO distribution(C-AE2S and N-AE2S) and cationic surfactant tetradecyltrimethylammonium bromide (TTAB) mixtures under different molar ratios were investigated. Their surface activities, adsorption, and spreading performances were investigated by static/dynamic surface tension measurements, molecular dynamics simulation, and dynamic contact angle techniques at 298 K. The static surface tension analysis reveals that the critical micellization concentration (cmc) values and the surface tension at cmc (γcmc) of the binary systems are much lower than that of the individual component. Compared with C-AE2S/TTAB, N-AE2S/TTAB systems have higher cmc and lower γcmc. It was found from the molecular dynamics simulation that negative charges of C-AE2S were drastically neutralized by the positively-charged TTAB at the interface in the system of C-AE2S/TTAB. The dynamic surface tension results indicate that the adsorption process of aqueous solutions for both C-AE2S/TTAB and N-AE2S/TTAB are mixed diffusion-kinetic adsorption mechanisms. From the dynamic contact angle measurements, it could be obtained that the mixtures exhibit better spreading behavior than that of the individual component and N-AE2S/TTAB systems have lower contact angles than that of C-AE2S/TTAB at the same mixing ratios. [ABSTRACT FROM AUTHOR]

The global trade network can be viewed from different perspectives. The common ones are the volume of exports and the number of countries that export products. The variation in number of exporting countries for products has been studied over the years. The U.S. dollar has been used for invoicing exportation in global trade, and its variation in values against global currencies negatively affects the volume of exports and the number of exporters. United States dollar indices (USDX) have been globally used to measure the values of global currencies against the U.S. dollar. Many studies have been done on the effect of the global economic crisis on global trade networks. However, scholars have not yet developed a complex dynamical model and established the critical transitional or threshold values that separate the resilient network of exporting countries from a non-resilient one. This study modelled the dynamic representation of a complex network of exporting countries by modifying Lotka-Volterra models. Using the developed model and empirical data USDX and export data of 161 countries from 1971 to 2020, the critical transition values have been calculated for different phases of economic crises. This study references five major crises, revealing that the variation of U.S. dollar indices significantly impacts global network system resilience. It suggests that policies reducing trade restrictions among trading partners are more important than controlling variation in U.S. dollar indices. This information will be crucial in addressing future crises like the Russian-Ukraine conflict.

Foam properties and surface dilational rheology of single and mixed LHSB (lauramidopropyl hydroxyl sulfobetaine)-OAB (oleic amide propyl betaine) surfactants were measured to investigate the synergism between the two components. Experimental results showed obvious synergistic effects in foam stability, dilational modulus, and phase angle between LHSB and OAB. Moreover, interaction parameters were calculated to quantitatively characterize the synergism. The negative interaction parameters between LHSB and OAB demonstrated that there was an attractive interaction between LHSB and OAB, and the attractive interaction contributed to forming the dense surfactant layer at the liquid/air layer, which in turn improved foam stability. The negative values of parameters reached their maximum when the LHSB: OAB molar ratio ranged from 1:1 to 1:2, the same time the foam stability reached its maximum. The interaction between LHSB and OAB was confirmed by 2D NOSEY (two-dimensional nuclear overhauser enhancement spectroscopy) experiments, the interaction between LHSB and OAB could be attributed to the hydrogen bonding or the electrostatic interaction between the hydrophilic groups of the two surfactants. [ABSTRACT FROM AUTHOR]

Phosphorus, Iron and Aluminum are the key elements in solar cell materials and typically difficult to remove during MG-Si refining process. The evaluations of their thermodynamic properties in Si dilute solutions are crucial for the possibility and efficiency of impurities elimination process. In the present study, the activities and self-interaction parameters of P、Fe and Al in molten Si at 1723-1873 K were investigated by applying the models of mass action concentrations for Si-P、Si-Fe and Si-Al Binary Solution. The activities of Fe, Al with a mass concentration range of 1–2000 ppmw and P with a mass concentration range of 1–100 ppmw in dilute Si-based solutions are calculated by the model. The effects of temperature and impurity concentration on the thermodynamic properties of Si-based binary solutions were also determined by the models. [ABSTRACT FROM AUTHOR]

The mixed micellar properties of double-chained surface active ionic liquid (1, 3-didecyl-2-methylimidazolium chloride or TEGO) with two conventional cationic surfactants, dodecyltrimethylammonium bromide (DOTAB) and cetyltrimethylammonium bromide (CTAB) were investigated by using surface tension and conductivity experiments in aqueous solution at 303.15 K. TEGO is a special surface active agent with two specific critical micelle concentrations (CMC). To consider the effect of hydrophobic groups in synergism between components (surfactant and TEGO) in the mixed micelle, two cationic surfactants were selected that differed only in the length of the hydrocarbon chain (DOTAB: C12 and CTAB: C16). The experimental critical micelle concentration (CMCexp), degree of micellar dissociation (g), the ideal critical micelle concentration (CMCid), micellar mole fractions ( X 1 m and X 2 m ) and the interaction parameter (βm) were determined by using Rubingh's model. The achieved βm of the studied system is negative in the whole compositions denoting the synergistic interaction between components and their values increase with increasing chain lengths of surfactant from DOTAB to CTAB. The activity coefficients ( f 1 m and f 2 m ) are always less than unity in all mole fractions signifying non-ideality in the mixtures. Thermodynamic functions for mixed systems were estimated. The standard Gibbs energy of micellization (Δ G m i c 0 ) associated with transfer of surfactant monomers from the bulk phase to micelle phase was evaluated according to Zana's model in different situations and discussed with logical points in the new approach. The results show that the effect of hydrophobicity can regulate the synergism between cationic surfactants in the same electrical charges of head groups. [ABSTRACT FROM AUTHOR]

For the purpose of determining the interaction parameters between Mn and Al, and the influence of Mn on Al2O3 inclusions formation in the Fe-Mn-Al-O melts with high Mn and Al contents, three groups of Fe-Mn-Al-O melts with the initial Al content of 3, 5, and 7 mass% and different Mn contents were equilibrated with pure solid Al2O3 in an Al2O3 crucible at 1873 K and Ar-H2 atmosphere. Then, the interaction parameters between Mn and Al were deduced using the WIPF (Wagner's Interaction Parameter Formalism) and the R-K polynomial (Redlich-Kister type polynomial), respectively. From the WIPF, the first- and second-order interaction parameters, e Al Mn and r Al Mn , were determined to be 0.0292 and −0.00016, respectively. From the R-K polynomial, the binary interaction parameters, Ω Mn - Al 0 and Ω Mn - Al 1 , were determined to be 73,439 J/mol and −34,919 J/mol, respectively. The applicability of the WIPF to high Mn and Al content Fe-Mn-Al-O melts was investigated by comparing the Al activity calculated by the WIPF and the R-K polynomial using the obtained data. The results showed that WIPF can be used in high Mn and Al content melts in the current concentration range. Further from the iso-activity contours of Al, the activity of Al increases with increasing Al or Mn content. Finally, the thermodynamic calculations show that the addition of Mn decreases the equilibrium O content at the same Al content, making the formation of Al2O3 inclusions easier. [ABSTRACT FROM AUTHOR]

Data on the solubility of oligomer polystyrene (PS) and poly(methyl methacrylate) (PMMA) of various molecular weights have been obtained. The binodal and spinodal curves of the phase state diagram with the upper critical solution temperature (UCST) are constructed through simulation within the framework of the Flory–Huggins theory. The influence of the molecular weight of polymers on the contribution to their mixing has been compared, and correlation curves have been plotted. The interaction parameters were calculated and the mixing thermodynamics of the components was evaluated. The largest contribution was made by the entropy component. Also, it has been shown using IR spectroscopy that there is no interaction between the functional groups of polystyrene and poly(methyl methacrylate) in a homogeneous mixture. [ABSTRACT FROM AUTHOR]

This study investigates the use of equilibrium molecular dynamics (EMD) simulations for determining interfacial thermal resistance (ITR) at solid-liquid interfaces. The Green-Kubo theorem is typically used for this purpose, but it may not be suitable for hydrophobic conditions where the interaction between liquid and solid atoms is weak. Two EMD simulation methods were used to calculate ITR at interfaces under different wetting conditions: one using instantaneous temperature differences and the other using instantaneous heat flux. The data derived from the EMD simulation using instantaneous temperature difference could not converge due to weak intermolecular interactions, leading to inaccurate ITR calculations. To address this issue, a method for calculating ITR in the frequency domain is proposed. Results showed that both EMD methods produced different results from non-equilibrium molecular dynamics (NEMD), with the ITR of EMD using instantaneous heat flux being higher than that of NEMD, while the ITR of EMD using instantaneous temperature was lower, and in good agreement with NEMD. Overall, this study highlights the limitations of using EMD simulations for calculating ITR at solid-liquid interfaces in hydrophobic conditions and proposes a new method for improving accuracy in these situations. [ABSTRACT FROM AUTHOR]

In this study, the micellization behavior of the sodium cholate (SCH) and sodium dodecyl sulfate (SDS), in aqueous solution in pure state, and mixture of them (SCH + SDS) in different mole fractions were investigated by conductometric method at 298.15 K. The obtained data from experimental measurements were used to determination of the critical micelle concentration (CMC) of surfactants in pure and mixed state. Also according to Regular Solution Theory (RST), were calculated the following parameters: the interaction parameter between surfactants in the mixed system ( ), activity coefficient ( ، ), mole fractions of the components in the mixed micelle ( , ) and thermodynamic parameters such as Gibbs free energy of micellization ( ) and excess free energy ( ). The results obtained show that in the anionic-anionic mixture, the interaction parameter is low and the activity coefficients show a small deviation from the ideal state, the standard Gibbs free energy of micellization ( ) are negative values, this shows that the micelle formation process take place spontaneously.

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. [ABSTRACT FROM AUTHOR]

For the purpose of determining the interaction parameters between Mn and Al, and the influence of Mn on Al2O3 inclusions formation in the Fe-Mn-Al-O melts with high Mn and Al contents, three groups of Fe-Mn-Al-O melts with the initial Al content of 3, 5, and 7 mass% and different Mn contents were equilibrated with pure solid Al2O3 in an Al2O3 crucible at 1873 K and Ar-H2 atmosphere. Then, the interaction parameters between Mn and Al were deduced using the WIPF (Wagner’s Interaction Parameter Formalism) and the R-K polynomial (Redlich-Kister type polynomial), respectively. From the WIPF, the first- and second-order interaction parameters, eAlMn and rAlMn, were determined to be 0.0292 and −0.00016, respectively. From the R-K polynomial, the binary interaction parameters, ΩMn-Al0 and ΩMn-Al1, were determined to be 73,439 J/mol and −34,919 J/mol, respectively. The applicability of the WIPF to high Mn and Al content Fe-Mn-Al-O melts was investigated by comparing the Al activity calculated by the WIPF and the R-K polynomial using the obtained data. The results showed that WIPF can be used in high Mn and Al content melts in the current concentration range. Further from the iso-activity contours of Al, the activity of Al increases with increasing Al or Mn content. Finally, the thermodynamic calculations show that the addition of Mn decreases the equilibrium O content at the same Al content, making the formation of Al2O3 inclusions easier.

With the development of circuit integration technology, the requirements for defects in copper interconnects have become more stringent. The residual SiO 2 particles on the copper surface can seriously affect circuit performance and require more efficient and thorough removal. This article investigates the effects of a novel cleaning solution composed of citric acid (CA), alkyl polysaccharide glycosides (APG1214), and dodecylbenzene sulfonic acid (LABSA), aimed at improving the removal efficiency of SiO 2 and maintaining the integrity of copper surface. The optimal concentrations of APG1214 and LABSA were determined through contact angle and surface tension analysis. It was found that when APG1214 (2000 ppm) and LABSA (1000 ppm) were combined in a 3:2 vol ratio in CA solution (0.6 wt%), the highest particle removal efficiency (99.5 %) could be achieved while minimizing surface roughness. The results of scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirmed these findings. Combining quantum chemical calculations, new insights into the mechanism of action of different components in clean solutions have been proposed: 1. Similar to CA, LABSA and APG1214 demonstrate a strong affinity for copper, synergistically facilitating the cleavage of Cu-Si bonds. 2. Alternating adsorption of LABSA and APG1214 on free silica particles prevents their re-adsorption onto copper surfaces. 3. Furthermore, their orderly adsorption on copper mitigates the corrosive chelation effect of CA, providing a protective mechanism. These findings are pivotal for the development of advanced, multifunctional cleaning solutions. [Display omitted] • Citric acid can break the chemical bond between SiO 2 and Cu. • Surfactants adsorb onto SiO 2 surface to form encapsulation, changing the Zate potential and hydrophobicity of particles. • Synergistic effect of composite surfactants enhances wetting and particle removal efficiency. [ABSTRACT FROM AUTHOR]

Herein, the mixed micellization behavior between bile salt (sodium cholate, SCH) and two cationic surfactants (tetradecyltrimethylammonium bromide, TTAB and cetyltrimethylammonium bromide, CTAB) has been investigated in aqueous solution by UV–Vis spectrophotometric and conductometric methods at 298.15 K. The critical micelle concentration (CMC) of SCH-surfactant mixtures was measured by using the tautomers of 1-phenyl-1, 3-butadione (or benzoylacetone, BZA). The CMC values of the mixtures at various mole fractions (yi) were lower than the pure surfactants (due to the strong electrostatic attraction between anionic and cationic components after mixing). Regular solution theory (RST) was used to estimate the synergistic (or non-ideal behavior) of the mixed micelles. Different parameters of micellization such as the micellar compositions ( X 1 m and X 2 m ), interaction parameter ( β m ) and the activity coefficients of components in the mixed micelle ( f 1 m and f 2 m ) along with thermodynamic parameters are calculated and discussed. [ABSTRACT FROM AUTHOR]

Purpose: Use of Flory–Huggins interaction parameter and contact angle values to predict the suitability of the drug-polymer system for the production and stability of nanosuspensions. Material and Methods: Melting point depression of the drug was measured using differential scanning calorimetry. Interaction parameter, χ, was calculated using the melting point depression data to elucidate the drug-polymer interaction strength to predict the suitability of the drug-polymer system for the production and stability of nanosuspensions. Contact angle of the drug films were measured with purified water and 0.1%w/w polymer solutions to predict polymer's suitability for the production and stability of nanosuspension. Nanosuspensions were manufactured to validate the application of the melting point depression approach along with surface property information. Results: All three polymers, HPMC, Soluplus®, and poloxamer exhibited a negative interaction parameter with naproxen and budesonide. Higher negative interaction parameter values for the naproxen-polymer system indicated stronger drug-polymer interactions, while smaller negative interaction parameter values for the budesonide-polymer system indicated weaker drug-polymer interactions. Interaction parameter was not obtained for fenofibrate with HPMC and Soluplus®, and similarly, no interaction parameter was obtained for carvedilol with HPMC, most likely due to weaker drug-polymer interactions. All three polymers provided lower equilibrium contact angle values when compared to purified water, indicating an affinity for polymers. Conclusions: Successful production and stability of several nanosuspensions were correlated with Flory–Huggins's interaction parameter and contact angle values. In the absence of melting point depression, contact angle values can also be used predict the agglomeration tendencies as we have shown for this study. [ABSTRACT FROM AUTHOR]

Objective The branched alcohol ether sulfonate TEOS was synthesized by branched alcohol ether TEO, 1,3-propane sulfonate as a raw material. The surface tension (γcmc) under the concentration of micelle concentration (cmc) and the critical micelle concentration of branched alcohol ether TEO, TEOS, and the amphoteric Gemini surfactant GCS12 in distilled water was determined. The solution properties of branched alcohol sulfonates and amphoteric Gemini surfactant were studied. Methods The surface activity of the alcohol ether sulfonate TEOS and the GCSl 2 compounding system was evaluated, and the interaction between them was studied. The interfacial activity between the binary compound system and Changing crude oil was also studied. Results The experimental results show that the content of synthetic alcohol ether sulfonate is 96.5%, it has good salt tolerance. The cmc of TEO, TEOS, GCSl 2 in distilled water is 0. 05 mmol/ L, 0.40 mmol/L, 0.05 mmol/L, respectively, and γcmc. is 26. 02 mN/ m, 34. 58 mN/m, 25. 27 mN/m, respectively. The theoretical study of solution thermodynamics showed that TEOS and GCSl 2 had medium interaction to significantly reduce the critical micelle concentration of mixed solution. The mixed solution prepared with simulated formation water at 60 °C reached the minimum interfacial tension when n(TEOS): nCGCS12) = 3:1. When the amount of salt is 200 g/L, the interfacial tension is 0.021 mN/m. Conclusions The mixing systems of branched alcohol ether sulfonate and amphoteric Gemini surfactant have better temperature resistance and high interface activity, which can provide a technical support for the development of oil displacement surfactant. [ABSTRACT FROM AUTHOR]

The thermodynamic properties of impurity components in silicon solutions play an important role in the chemical removal process to the metallurgical route. In this paper, the component activity coefficients and interaction parameters of dilute silicon solutions were estimated by the molecular interaction volume model (MIVM). The activity coefficients (γi) of component i in dilute binary Si-i and ternary Si-i-j solutions at 1687-1873 K were firstly calculated. The concentration dependences of the interaction parameter and activity coefficient were also obtained. The self-interaction parameters (εi,i) for Si-i system were obtained as εB,B= -2.728-362.031/T, εAl,Al = 2.157-1876.776/T, εFe,Fe= -4.842+14445.926/T and εP,P = -2.543+13767.036/T. At the same time, the interaction parameters among components B, Al, and Fe in dilute ternary Sii- j solutions were also derived as εFe,B=-1.2758-2946.306/T, εAl,B = 0.7467-9765.9298/T and εFe,Al= -1.39677+3319.6803/T. Most important of all, the temperature dependences of the interaction parameters and activity coefficients in dilute Si-i and Si-i-j solutions with a certain i or j concentration were deduced. The results show that the predicted self-interaction parameters of B, Al, Fe, and P in binary silicon solutions reasonably agree with the experimental data. This further shows that MIVM is of reliability and can be expanded to a multi-component dilute silicon solution.

Aggregation and adsorption properties of benzyldimethylhexadecylammonium chloride (BDHAC) with three cationic alkanediyl-1,s-bis(tetradecyldimethyl-ammonium bromide) gemini surfactants, viz. butanediyl-1,4-bis(tetradecyldimethylammonium bromide), pentanediyl-1,5-bis(tetradecyldimethylammonium bromide) and hexanediyl-1,6-bis(tetradecyldimethylammonium bromide) respectively referred to as 14-4-14, 14-5-14 and 14-6-14 (in general 14-s-14, where s = 4, 5, 6) have been studied by tensiometric, conductometric, fluorimetric and dynamic light scattering experimental methods at 298.15 K. The studies were conducted at various compositions of the mixed systems ranging between 0 and 1. The parameters determined include different physicochemical and interaction parameters. The negative values of interaction parameters obtained for mixed micelle formation point out the attractive interaction among the components and lead to non-ideality which has been theoretically treated by Clint's and Rubingh's models. The BDHAC + 14-s-14 mixtures in different mole fractions were used in the synthesis of very stable silver nanoparticles (Ag NPs) in aqueous media, which were characterized by UV-visible spectroscopy. Dynamic light scattering measurements revealed that the size of micelles as well as Ag NPs increases with the increase in mole fraction of BDHAC in the mixtures and the size of Ag NPs can be very much controlled by using mixtures of surfactants. [ABSTRACT FROM AUTHOR]

The imidazolinium chloride salts have improved as a potential new material for a wide variety of industrial operations, due to their exceptional structures and properties. Therefore, recognition of the surface proprieties and thermodynamic criteria of this product is extremely important for fundamental and industrial operations. In this investigation a mixture of fatty imidazolinium chlorides was synthesized dealing with a novel method using sunflower oil as a promoter of fatty acids. The reaction of ethane-1,2 diamine with a fatty acid yields a fatty imidazoline molecule. Hydrochloric acid was used to obtain fatty imidazolinium hydrochlorides with cationic surfactant properties. A FT-IR and NMR spectroscopic technique was using to establish the synthetic structure. The surface tension and conductivity as a function of the surfactant concentration in aqueous solution were measured at distinct temperatures, to figure out the micellization, adsorption and aggregation characteristics in aqueous solutions. Formerly the effect of temperature on the CMC was investigated. The HLB values were assumed for our surfactant and the results achieved indicate that it is O/W emulsifier. The Krafft point was identified at 288.45 K. All Surface adsorption parameters like, the maximum surface excess concentration (Γmax), minimum area per molecule (Amin), effectiveness (πCMC), and efficiency of surface tension reduction (pC20) were calculated using Gibb's equation. Finally, an attentive study of the thermodynamic aspects of air-ionic surfactant aqueous system reveals that the process of both micellization and adsorbtion was spontaneous and that adsorption is more favored than micellization. [ABSTRACT FROM AUTHOR]

Surfactant systems have been frequently used as pseudomodels for investigating interactions of drugs with biological membranes because of their structural similarities with the latter. This helps to understand complicated yet very important biological processes like diffusion of bioactive moieties through biomembranes. The current study deals with voltammetric and spectroscopic studies to evaluate the interaction of a potential antibacterial drug, gatifloxacin (GTF), with a cationic surfactant, dodecyltrimethylammonium bromide (DTAB), and an anionic surfactant, sodium dodecyl sulfate (SDS), under physiological conditions (phosphate buffer, pH 7.4). For more detailed insight into the GTF–ionic surfactant interactions, density and acoustic data were also recorded and used to calculate several important parameters, namely, apparent molar volume (ɸV), isentropic compressibility (Ks), and apparent molar isentropic compressibility (ɸK) at T = 298.15, 303.15, 308.15, and 313.15 K. Values for partial molar volume (ɸVo), partial molar expansivity ɸEo, specific acoustic impedance (Z), relative association (RA), intermolecular free length (Lf), and sound velocity number (U) were also obtained. The interpretation of the concentration dependence of the above‐mentioned quantities using a cosphere overlap model led to a better apprehension of solute–solute and solute–solvent intermolecular interactions present in the investigated system, whereas cyclic voltammetry and ultra violet (UV)–visible spectroscopic studies assisted in predicting the location of adsorbed GTF molecules within the DTAB and SDS micelles. [ABSTRACT FROM AUTHOR]

Recently, ionic liquids with surface-active properties due to the specific characteristics (such as green solvent) have been considered. In this research, the interfacial and micellization behaviors of binary mixtures of an ionic liquid (1-hexyl 3-methylimidazolium chloride or C6mimCl) and cationic surfactant (Cetyltrimethyl ammonium bromide or CTAB) were studied at various mole fractions (0.1-0.9). The surface tension technique was used to determine CMC values of surfactants in pure and mixed states.In the pure components, the weak interactions between C6mimCl and water (compared with CTAB and water) increase the tendency of CTAB to adsorb at the liquid–vapor interface (higher hydrophobicity and lower CMC for CTAB). The Experimental results were analyzed according to the regular solution model developed by Client, Rubingh, Rosen and others. Interaction parameter (βm), mole fractions ( ), activity coefficients ( ) were calculated and analyzed at the micellar phase.Also, the thermodynamic parameters such as maximum surface excess (max), surface pressure ()and minimum area per molecule (Amin) calculated and investigated. The results show that the activity coefficients values are less than unity for studied system, indicating non-ideal behavior and attractive interactions between ionic liquid molecules and surfactants in the mixed micelles. Negative interaction parameter (βm) of the systems at the mixed micelle indicates the synergism of the mixing process. By reducing the surface tension (σ) increased the values of max (or decreased the values of Amin).

We investigated the influence of an additive (50 mmol kg–1 NaCl/300 mmol kg–1 urea [U]) on the aggregation of amphiphilic promethazine hydrochloride (PMH) drug and cationic hydrotrope–aniline hydrochloride (AnHCl) mixtures at various temperatures and ratios. The drug PMH is mostly used for the treatment of allergic symptoms. The obtained critical micelle concentration (cmc) values are well below the cmcid (ideal cmc) value, which confirms interactions between components PMH and AnHCl in the solution mixture. The micellar mole fraction (X1Rub, X1Rod, and X1id) of the first component (AnHCl) was evaluated using different models, which suggested greater involvement of AnHCl in mixed micelles (as expected); besides, the obtained micellar mole fraction values increase with increase in the mole fraction (α1) of AnHCl. The interaction parameter (β) values obtained were negative, which confirms attractive interaction or synergism among the components. Activity coefficients (f1Rub [AnHCl] and f2Rub [PMH]) values are always found below one confirming the nonideality as well as attractive interaction between the components. Different physicochemical parameters evaluated suggested attractive interaction between the components (PMH and AnHCl) in all studied solvents; however, in salt media, the interaction increases to some extent, whereas in urea media, it decreases to some extent. Diverse thermodynamic parameters (Gibbs free energy [ΔGm0], enthalpy [ΔHm0], and entropy [ΔSm0]) of micellization were computed and discussed separately. The excess free energy (∆GexRub) values of all systems were negative, suggesting higher stability of formed mixed micelles as compared with singular‐component micelles. [ABSTRACT FROM AUTHOR]

A set of Nd3+ doped vanadium arsenate glasses having formula 25%As 2 O 3.70%V 2 O 5. (5-x) %CuO.x%Nd 2 O 3 (where x = 0, 0.5, 1, 1.5, 2 mol%) are manufactured by the ordinary melt quenching technique. These glasses are investigated by several tools. Complete amorphous phase is confirmed for all samples. The calculated optical basicity decreases with the increase of Nd 2 O 3 mole% in the glasses, while the molar refractive index follows an opposite trend. The metallization criterion calculation confirms the insulating nature of the samples, and such nature increases with increasing the Nd 2 O 3 content. T g , T c and thermal stability of the glasses are found to increase with increasing the Nd 2 O 3 content in the glasses. Continuous addition of the Nd3+ ions increases the thermal conductivity of the glasses from 0.11 to 0.178 W/m.oC. Emission spectra due to 365 nm excitation light demonstrates emission peaks around 506, 542, 580 and 635 nm from the samples. [ABSTRACT FROM AUTHOR]

Promethazine hydrochloride (PMT) is a phenothiazine tranquilizer compound used as a sedative, analgesic, anticholinergic, antihistaminic and antipsychotic drug. The effect of various additives such as urea, glucose, glycine and sodium chloride (NaCl) on the mixed micellization of PMT and an ester-functionalized pyridinium gemini surfactant, (4, 4′-(propane-1, 3-diyl) bis (1-(2-(hexadecanoyl oxy) ethyl) dipyridinium bromide (16-3-16), has been studied at a constant temperature using surface tension, conductivity and fluorescence techniques. The different micellar and interfacial parameters were evaluated which signify the non-ideal behavior of all mixed systems. The thermodynamic studies revealed that the micellization and adsorption processes are spontaneous with the latter being more prominent than the former since the values of standard Gibbs free energy of adsorption (Δ G ad 0 ) are more negative than those of standard Gibbs free energy of micellization ( Δ G m 0 ). Besides, the excess free energy change of micellization ( Δ G ex m ) was determined which also showed negative values. These studies are specially aimed to get a deep understanding of the effect of different biologically significant molecules on the mixed micellization of the PMT-(16-3-16) micellar systems so as to ensure the bioavailability and effectiveness of the drug. [ABSTRACT FROM AUTHOR]

Theoretical investigations on the micellization of mixtures of (i) amino acid‐based anionic surfactants [AAS: N‐dodecyl derivatives of aminomalonate, −aspartate, and ‐glutamate] and (ii) hexadecyltrimethylammonium bromide (HTAB), were carried out at different mole ratios. Variation in the theoretical values of critical micelle concentration (CMC), mole fraction of surfactants in the micellar phase (X), at the interface (Xσ), interaction parameters at the bulk/interface (βR/βσ), ideality/nonideality of the mixing processes, and activity coefficients (f) were evaluated using Rubingh, Rosen, Motomora, and Sarmoria‐Puvvada‐Blankschtein models. CMC values significantly deviate from the theroretically calculated values, indicating associative interaction. With increasing mole fraction of AAS (αAAS), the magnitude of the (βR/βσ) values gradually decreased, considered to attributable to hydrophobic interactions. With increasing αAAS, the micellar mole fraction of HTAB (X2) decreased insignificantly and X2 values were higher than those compared to AAS for all combinations, due to the dominance of HTAB in micelles. Micellar mole fraction at the ideal state of AAS (X1ideal) differed from micellar mole fraction of AAS (X1), indicating nonideality in the mixed micellization process. Gibbs free energy of micellization (∆Gm) values are more negative than the free energy of micellization for ideal mixing (∆Gmideal), indicating the micellization process is spontaneous. With increasing αAAS, the enthalpy of micellization (ΔHm) and entropy of micellization (ΔSm) values gradually increased, which indicates micellization is exothermic. The different physicochemical parameters of the mixed micelles are correlated with the variation in the spacer length between the two carboxylate groups of AAS. [ABSTRACT FROM AUTHOR]

It is important to study the mechanism of wettability of Zhaozhuang coal with surfactant compoundings in order to prevent dust disaster in the process of coal seam mining. By means of molecular simulation, the amounts of water absorbed by different systems, which are composed of monomer surfactant molecules and Zhaozhuang coal molecules or compounding surfactant molecules and Zhaozhuang coal molecules, were compared in this paper. The simulation results show that the system composed of 0.2% sodium dodecyl benzene sulfonate (SDBS) and 0.3% alcohol polyoxyethylene ether (AEO3) had the maximum water absorption amount of 479, which is significantly better than that of other compounding methods and of each monosurfactant system. Analysis results show that the interference of non-ionic surfactant can greatly reduce the electrostatic repulsion between ionic surfactants and make the adsorption sites on the Zhaozhuang coal molecule more compact. The experimental results show that the decreasing percentage of the contact angle of this type of compounding solution on Zhaozhuang coal was 83.74%, which is the best of the six compounding methods. It has a high degree of consistency with the simulation results, and the molecular simulation method applied in this paper shows that it is convenient and accurate. This research plays a guiding role in dustproof work in Zhaozhuang coal mining. [ABSTRACT FROM AUTHOR]

The substantial increase in the efficiency of organic solar cells achieved in recent years would not have been possible without work on the synthesis of new materials and understanding the relationship between the morphology and performance of organic photovoltaic devices. The structure of solvent-cast active layers is a result of phase separation in mixtures of donor and acceptor components. To a large extent, this process depends on the interactions between the components of the mixture. Here, we present a systematic analysis of the morphology of poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl-C71-butyricacid methyl ester (PC70BM) films in terms of the ternary phase diagram. The interaction parameters between PCDTBT and four different solvents, namely chloroform, chlorobenzene, o-dichlorobenzene, and toluene, were estimated based on swelling experiments. Based on these values, ternary phase diagrams of PCDTBT:PC70BM in different solvents were calculated. The morphology of spin-coated films with different blend ratios cast from different solvents is discussed in terms of the obtained phase diagrams. [ABSTRACT FROM AUTHOR]

Herein, we employed the conductometric measurement technique for the estimation of the interaction between two oppositely charged surfactants (anionic, sodium dodecyl sulfate [SDS] and tetradecyltrimethylammonium bromide [TTAB]) in two chloride (NaCl/NH4Cl) salts in the range of temperatures from 298.15 to 318.15 K. The deviation of experimental critical micelle concentration (cmc) from the corresponding ideal values of cmc (cmcid), the values of interaction parameters (β), and activity coefficients (f1 and f2) of the components reveal the existence of the interaction amongst the investigated components. The attained cmc values for SDS/SDS + TTAB decline with the rise of temperature in H2O/electrolytes medium. The reduction of cmc in the presence of electrolytes reveals the facilitated micellization in the electrolyte medium. The assessed values of the micellar mole fraction of TTAB (X1) obtained from theoretical models signify the significant contribution of TTAB in SDS + TTAB mixed micellization. The estimated negative values of free energy (ΔGmo) and excess free energy (ΔGex) of micellization reveal that micellization is spontaneous and mixed micelles are extra stable than distinct micelle, respectively. The enthalpy (ΔHmo) and entropy (ΔSmo) in addition transfer energies of micellization were also evaluated and explained thoroughly. [ABSTRACT FROM AUTHOR]

Abstract Blending multidonor or multiacceptor organic materials as ternary devices has been recognized as an efficient and potential method to improve the power conversion efficiency of bulk heterojunction devices or single‐junction components in tandem design. In this work, a highly crystalline molecule, DRCN5T, is involved into a PTB7‐Th:PC70BM system to fabricate large‐area organic solar cells (OSCs) whose blend film thickness is up to 270 nm, achieving an impressive performance of 11.1%. The significant improvement of OSCs after adding DRCN5T is due to the formation of an interconnected fibrous network with decreased π–π stacking and enhanced domain purity, in addition to the optimized vertical distribution of PTB7‐Th and PC70BM, producing more effective charge separation, transport, and collection. The optimized morphology and performance are actually determined by the miscibility in different components, which can be quantitatively described by the Flory–Huggins interaction parameter of −0.80 and 2.94 in DRCN5T:PTB7‐Th and DRCN5T:PC70BM blends, respectively. The findings in this work can potentially guide the selection of an appropriate third additive for high‐performance OSCs for the sake of large‐area printing and roll‐to‐roll fabrication from the view of miscibility.

We demonstrate the directional alignment of perpendicular‐lamellae domains in fluorinated three‐armed star block polymer (BP) thin films using solvent vapor annealing with shear stress. The control of orientation and alignment was accomplished without any substrate surface modification. Additionally, three‐armed star poly(methyl methacrylate‐block‐styrene) [PMMA‐PS] and poly(octafluoropentyl methacrylate‐block‐styrene) were compared to their linear analogues to examine the impact of fluorine content and star architecture on self‐assembled BP feature sizes and interdomain density profiles. X‐ray reflectometry results indicated that the star BP molecular architecture increased the effective polymer segregation strength and could possibly facilitate reduced polymer domain spacings, which are useful in next‐generation nanolithographic applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1663–1672 [ABSTRACT FROM AUTHOR]

As a class of novel surfactants, Gemini surfactants usually exhibit fairly excellent interfacial properties in aqueous solutions on account of the unique structure. They have significant application and development potential for industrial production. However, the mixing properties of Gemini surfactants with conventional surfactants are the key to their application. The equilibrium surface tension curves of anionic/nonionic surfactant mixtures based on the sulfonate Gemini surfactant (SGS‐12) were measured using the Wilhelmy Plate method. The parameters of surface adsorption, the interaction parameters between anionic and nonionic surfactants, and the thermodynamic parameters of micelle formation were calculated from the corresponding equations. In addition, the dynamic surface tension (DST) curves of anionic/nonionic surfactant mixtures were examined through bubble profile analysis, and the diffusion performance parameters were acquired from empirical formulas. The solubilization of pyrene in micelle solutions was studied using UV–vis absorption spectroscopy. The results show that the interaction parameters of all anionic/nonionic surfactants are negative, indicating that there is a synergistic effect on reducing the surface tension. For the SGS‐12/OP‐10, SGS‐12/Tween 80, SGS‐12/AEO9, and SGS‐12/APG0810 mixtures, the optimum mixing ratios are 6:4, 7:3, 7:3, and 8:2, respectively. The thermodynamic data of micelles show that the formation of mixed micelles for SGS‐12/APG0810 mixtures is an enthalpy‐driven process. The tendency of DST curves of the SGS‐12/APG0810 mixture is similar to that of SGS‐12. In comparison with single‐surfactant solutions, the anionic/nonionic surfactant mixtures show stronger solubilization capacity toward pyrene. [ABSTRACT FROM AUTHOR]

Chitosan (Chi) and gelatine (Gel) polymer blends with ZnO nanoparticles loaded on silica were synthesized through a simple solution method under ultrasonic irradiation at different concentration ratios (5:3, 1:3 and 3:5). The viscosity characteristics of the nanostructure were investigated by using ultrasound irradiation to determine the behaviour of macromolecules in solution. Rheological characterization of the nanoparticles was determined. The experimental viscosity of the nanosystems was calculated with five different models including Huggins, Kraemer, Tanglertpaibul-Rao, Higiro and Rao. The results showed that the Huggins model was the best model for intrinsic viscosity determination of nanostructures at different concentration ratios and at sonicated or non-sonicated conditions. The voluminosity (V E) and the shape factor (υ) were calculated for the nanosystems. The Krigbaum and Wall parameter (Δb) along with the Chee parameter (μ) were calculated to understand the miscibility behaviour. The miscibility criterion was slightly affected by the collapse and cavitation. The intermolecular interactions occurring between polymers were investigated by comparing the experimental and ideal intrinsic viscosity. Characterization of the nanostructures was carried out via Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. • The Huggins model • The intrinsic viscosity • The ultrasonic irritation • Cavitational activity • Nanocolloidal system [ABSTRACT FROM AUTHOR]

The use of any new extractant requires the study of its tendency to form third phases. To understand the phase separation process it is important to have knowledge of the molecular scale phenomena present in the system. This includes the mixing of the substances and the behavior and nature of the aggregates. Here we report the mixing properties of N,N,N′,N′-tetra-(2-ethyl hexyl) diglycolamide (TEHDGA)–dodecane–isodecanol (in the absence and presence of micellar aggregates) which is recognized as a promising system for the separation of minor actinides through the conventional solvent extraction route. The nature of interactions between TEHDGA and isodecanol was investigated using several techniques, including density and speed of sound measurements, ultraviolet absorption spectroscopy and computational studies. The TEHDGA–isodecanol interaction was found to be favored over the inter-isodecanol interaction. On equilibrating the organic phase with nitric acid, some indication of pre-micellar aggregation was obtained. Increase of micellar aggregate size on addition of isodecanol was indicated. [ABSTRACT FROM AUTHOR]

Herein, we have studied the mixed micellization of Cetyltrimethylammonium bromide (CTAB) and Sodium dodecyl sulfate (SDS), in aqueous/various salts medium at several temperatures (298.15–318.15 K) by conductivity measurement method. The extent of interaction between CTAB and SDS was assessed from the values of ideal critical micelle concentration (cmc id) as well as experimental cmc. In attendance of salts, cmc values are obviously decreased from the corresponding values in aqueous medium. The magnitudes of micellar mole fraction of CTAB (X 1) and activity coefficients of CTAB & SDS (f 1 & f 2) were estimated based on different theoretical model and outcome disclose the effective involvement of CTAB in the mixed micellization. The executed values of both interaction parameters (β) and excess free energy of micellization were negative signifying the attractive interaction and stability of mixed micelles respectively. The executed negative values of Gibbs free energy change of micellization, ∆ G o m illustrate the spontaneous micellization of individual/mixed surfactant system. The other thermodynamic parameters Δ H o m (enthalpy change), and ∆ S o m (entropy change) were also calculated from the conventional standard equations. Molecular level interactions are disclosed by molecular dynamics (MD) simulation which showed that salts promote more interactions between the surfactants. Simulation snapshot of SDS-CTAB complex in H 2 O + KCl after 20 ns simulation (CTAB in blue-carbon, K in Magenta, Cl in green). Unlabelled Image • Aggregation of TTAB and CTAB is studied in the absence/presence of electrolytes. • Electrolytes reduce cmc of both pure and mixed surfactant systems. • Both the X 1 > X 1 id and negative values of β reveal the synergism between SDS and CTAB. • The Δ G ex values show the stability of mixed micelles. • MD simulation shows that salts promote more interactions between SDS and CTAB. [ABSTRACT FROM AUTHOR]

Abstract The micellization phenomena in the mixed system of the amphiphilic antidepressant drug imipramine hydrochloride (IPH) and cationic hydrotropes - aniline hydrochloride (AnH), ortho -toluidine hydrochloride (o -ToH), as well as para -toluidine hydrochloride (p -ToH)- in a water solution at a range of temperatures (288.15, 293.15, 298.15, and 303.15 K) was investigated using the conductometry method. In accordance with the regular solution theory (RST), along with other models, such as Rubingh's model, Rodenas's model, and so forth, various parameters were determined to attain a complete picture of the association behaviours of IPH and the hydrotrope mixtures. For every IPH-hydrotrope mixture, the critical micelle concentration (cmc) of the mixture along with the composition of the hydrotropes in the mixed micelle diverged from what they would have been in an ideal system, demonstrating non-ideal behaviour. The divergence amongst evaluated cmc and ideal cmc (cmc id) values viewing interaction amid studied constituents. The effects of the hydrotropes on the cmc of IPH (drug) were found to occur in the following order: p -ToH > AnH > o -ToH. The interaction parameters (β) were also evaluated to obtain detailed insights into the interactions amongst the studied constituents by applying a theoretical model introduced by Rubingh. The β values were negative, showing the presence of interactions between the binary mixtures of IPH and the hydrotropes. Micellar mole fraction (X 1) data estimated via the applied models in present system showed the attractive interactions between the IPH and hydrotropes as well as the intercalation of hydrotrope monomers between the drug IPH monomers constituting the micelle. Through the achieved thermodynamic parameters of the micellization of IPH under different conditions, the effects of temperature and the cationic hydrotropes, along with the impact of their concentrations on their association behaviours, were deduced. Highlights • Micellization phenomena of IPH and hydrotropes mixtures have been examined. • Various parameters were determined to obtain a complete perceptive of association behaviours of mixtures. • Effects of hydrotropes on cmc of IPH were found in order: p -ToH > AnH > o -ToH. • Negative β shows the presence of interactions between IPH-hydrotropes mixtures. • The Δ H m 0 values were found negative/positive at lower/higher temperature respectively. [ABSTRACT FROM AUTHOR]

The surface tension of the two mixed systems had been investigated in 0.1 M NaCl solution at 298.15 K respectively, including the surface tension of the anionic surfactant N-lauroyl-N-methyl taurine sodium (SDMT) and of the cationic surfactant dodecyltrimethylammonium chloride (DTAC), and zwitterionic surfactant dodecyl betaine (BS-12). The chemical surface properties of the two mixed systems were studied and the regular solution theory was applied to the two mixed systems. The results showed that the binary surfactant mixtures of SDMT/DTAC and SDMT/BS-12 exhibited synergism in surface tension reduction effectiveness, surface tension reduction efficiency and the mixed micelle formation according to ß values. It was also found that the results calculated by this theory agreed well with the experimental values. [ABSTRACT FROM AUTHOR]

The measurements of the surface tension of aqueous solutions of 10 monoterpene alcohols, MAs: (−)-β-citronellol, geraniol, tetrahydrolinalool, linalool, (−)-menthol, (−)-terpinen-4-ol, p-cymene-8-ol, α-terpineol, isoborneol and (−)-borneol were made at T = 293 K. On the basis of the obtained results the values of the adsorption constant, the excluded area per molecule at the interface and the interaction parameter were determined by fitting the experimental data to various adsorption models. Next the adsorption free energy of studied MAs was determined and discussed in terms of the preferred orientation of studied MAs at the water–air interface and molecular structure of MAs. [ABSTRACT FROM AUTHOR]

The micellisation behaviour between an amphiphilic drug propranolol hydrochloride (PPL) and cationic surfactant (Hyamine 1622) has been studied using conductometric technique at different concentrations. The critical micelle concentration (CMC), interaction parameter (βm), mixed micellar composition (, , and ), extent of counterion binding(α) and thermodynamic parameters for the micellisation process have been computed and discussed. The trend of interaction parameter of the PPL with Hyamine 1622 has been found to be dependent on the CMC values and the composition (more dependent on drug concentration). In an interesting phenomenon, it was observed that in the various compositions of PPL/Hyamine mixture produced two CMC's. Compared to the first micelle, the second micelle condensed more counterions and produced a higher aggregation number. Also, the interaction parameter (βm) is negative at all compositions indicating synergistic interactions between drug-surfactant. Activity coefficients ( and ) are always less than unity suggesting non-ideality in the mixtures. [ABSTRACT FROM AUTHOR]