Cmc Values Research Articles

Pluronic based neutral-ionic binary micellar surfactant systems for solubilizing the cationic methylene blue dye

The interaction of cationic methylene blue (MB) dye with binary micellar systems of non-ionic Pluronic®L-81 containing anionic sodium dodecyl sulfate (SDS) or cationic cetyl trimethyl ammonium bromide (CTAB) surfactants were probed through conductivity, uv-visible, FTIR, DLS, and zeta potential measurements with an objective to identify better solubilizing system at room temperature. The CMC of both SDS and CTAB was lowered in MB+L-81+SDS or CTAB systems. The absorption spectrum of MB showed a slight blue-shift with enhanced intensity upon increasing the concentration of anionic SDS and cationic CTAB, reflecting the strong electrostatic interaction and formation of micelles due to the solubilization of MB by L-81+SDS/CTAB systems. The higher negative value of ΔGm for L-81+SDS (-24.18 kJ/mol) than L-81+CTAB, (-17.07 kJ/mol) indicated better stability of MB in SDS system than CTAB. This could be attributed to the electrostatic attraction between dissimilarly charged MB (cationic) and SDS (anionic) in the ternary (MB+L-81+SDS) system and repulsive steric interaction between positively charged MB and CTAB. This was confirmed from micellar size analysis using dynamic light scattering (DLS) measurements and binding constant values. The estimated CMC values were comparable with the literature data. Hence, based on these results we propose that L-81+SDS binary system can be applied as a potential medium for removal of MB from the industrial effluents.

Effect of TIPA/TEA combined grinding aid on the behavior of quartz flotation in DDA system

In this paper, different dosages of TIPA, TEA and their combined grinding aid were added to the process of quartz grinding and their influence on the grinding efficiency and flotation recovery in DDA system was investigated. From the grinding and flotation experiments, It can be known that the effect of the combined grinding aid was better than that of a single reagent, which can not only significantly improve the grinding efficiency of quartz, but also increase the recovery of quartz from flotation. Based on the results of FT-IR spectroscopy, XPS analysis, quantum chemistry and solution chemistry calculations, it can be seen that the hydroxyl groups in the TIPA/TEA combined grinding aid formed hydrogen bonds with O on the (101) surface of quartz, while collector DDA was mainly electrostatically adsorbed on the surface of quartz with negative potential, and the introduction of combined grinding aid improved the adsorption of DDA, the grinding aid and collector played a synergistic role instead of competitive adsorption. The detection of contact angle and surface tension showed that the combined grinding aid can improve the hydrophobicity of quartz, reduce the surface tension and CMC value of DDA, and enhance the dispersibility of quartz, therefore, it can increase the recovery of quartz from flotation.

Synthesis and application of novel glucose derived nonionic gemini surfactant

AbstractA novel group of nonionic gemini surfactant (GTPEA) with ethylidene spacer structure was prepared from glucose‐lactone, triethylenetetramine, alkyl epoxy polyether and acyl chloride of different alkyl chain lengths. The chemical structure of GTPEA were characterised by Fourier‐transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) and high‐resolution mass spectrometry (HRMS). The thermal properties of the three surfactants were characterised by thermogravimetric analysis (TGA). The critical micelle concentrations (cmc values) of GTPEA with different hydrophobic chain lengths were measured using the Wilhelmy plate method (cmc: 1.58 × 10−5 to 5.01 × 10−6 mol/L). The solubilisation, emulsification and solubilisation performance tests showed the excellent surface properties of nonionic gemini surfactants. GTPEA‐12 with a hydrophobic carbon chain length of 12 carbon atoms was selected to explore the dispersing performance of surfactants on disperse dyes and the levelling performance of polyester fibre disperse dyes. The test results have shown that the dispersion force was 96%, and the particle size of 0.1 g disperse dye was 196 nm in 100 ml of 4 g/L GTPEA‐12 solutions. Finally, GTPEA‐12 was used as a levelling agent in the dispersion dyeing of polyester fabrics. GTPEA‐12 of 0.1 g/L can provide an excellent levelling effect of S(λ) = 0.026 for polyester and has little impact on the colour yield (K/S = 5.0) of polyester fabric.

Micellization and aggregation approach in aqueous amphiphilic ionic liquid and anionic polymer system

In this study, we investigate the aggregation of an ionic liquid (IL), 1-allyl-3-methylimidazolium bromide ([AMIM][Br]) in aqueous solution containing variable amounts of poly(diallyldimethylammonium) chloride (PDADMAc), using conductivity, density, and viscosity techniques in combination with the molecular dynamics simulation approach. The critical micelle concentration (cmc) after micellization for IL in solutions was derived from the conductivity measurements. The effect of PDADMAc on the physicochemical properties of IL in aqueous solution was investigated using comprehensive biophysical techniques such as UV-visible absorption spectroscopy, viscosity (η) and density (ρ) measurements. With the addition of PDADMAc concentration (0, 0.25, 0.05, and 0.1 g.l-1), cmc values increased due to the interaction between IL and PDADMAc. Our UV spectroscopy results showed that the interaction between PDADMAc and [AMIM][Br] was due to the significant differences in the interactions between the amide group of the polymer, the ionic liquid ions, and the water molecules. The apparent molar volumes (V) were calculated from the experimental densities for the (AMIM)(Br)-PDADMAc systems studied. Viscosity data decreased with increasing IL concentration and increased with [PDADMAc]. A computer simulation was used to investigate the aggregate structure between (AMIM)(Br]) and PDADMAc.

Modes of interaction and thermodynamic behavior of aggregation of CTAB + BSA mixtures in diols media: effects of diols composition and temperature

The micellization of cetyltrimethylammonium bromide (CTAB) and bovine serum albumin (BSA) mixture has been studied conductometrically in aq. solutions of different diols (1,2-propanediol (1,2-PrD), 2,3-butanediol (2,3-BD), and 1,5-pentanediol (1,5-PD)) media over the temperature range from 298.15 K to 323.15 K to gain insight into the mode and degree of interaction amongst the investigated constituents. The critical micelle concentration (cmc) values of the CTAB + BSA mixtures were attained initially low but enhanced with the rise in temperature in all the media studied. The values of the CTAB + BSA mixtures in the different diols media followed the order: The degree of micelle ionization (α) increased with increasing carbon chain length of diols and temperature. The Gibbs free energy () values associated with the micellization of the CTAB + BSA mixture were negative and revealed a lowering of the spontaneity of micellization with increasing carbon chain length of the diols. The enthalpy () and entropy () changes of micellization revealed that the micellization was exothermic and mainly an enthalpy-controlled process in aq.1,2-PrD and 2,3-BD media while the process being endothermic, and entropy controlled in the 1,5-PD medium. The contribution of the solvent to the thermodynamic parameters was assessed from free energy of transfer (), enthalpy of transfer (), and entropy of transfer () values. The enthalpy–entropy compensation parameters were also studied and discussed with proper reasoning.

Antimicrobial and Cytotoxic Activity of Novel Imidazolium-Based Ionic Liquids.

In this study, a series of 10 novel 1-methyl-3-octyloxymethylimidazolium derivatives carrying various anionic moieties (4-hydroxybenzenesulfonate, benzenesulfonate, carvacroloxyacetate, chloride, formate, propionate, thymoloxyacetate, vanillinoxyacetate, eugenoloxyacetate and trimethylacetate) were synthesized. Compounds were tested for their antimicrobial activity against six microbe strains (Staph-ylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Enterococcus faecalis, and Candida albicans), cytotoxic activity against the mouse melanoma cell line (B16 F10), and surface active properties. All synthesized compounds exhibited antimicrobial activity (expressed as minimum inhibitory concentration; in range of 0.10–27.82 mM/L), especially against Gram-positive bacteria and fungi. In addition, all compounds demonstrated cytotoxicity on B16 F10 cells (IC50 values 0.0101–0.0197 mM/L). Surface properties defined as CMC values, ranged from 0.72 to 32.35 mmol L-1. The obtained results provide an insight into the promising activity of a novel group of quaternary imidazolium derivatives having ionic liquid properties. The most potent compounds, containing a thymoloxyacetate and eugenoloxyacetate moiety, could be candidates for new antimicrobial agents or surfactants.

Hyperbranched ionic surfactants with polyether skeleton: Synthesis, properties and used as stabilizer for emulsion polymerization

A versatile strategy involves anionic ring-opening polymerization (AROP) and thiol-ene reaction was contributed for the construction of hyperbranched ionic surfactants. A series of hyperbranched surfactants composed of polyether skeleton and various ionic side groups such as anion, cation and zwitterion were synthesized and labeled as HPEanionic, HPEcationic and HPEzwitterionic, respectively. The chemical structures of all the intermediate and final products were verified by means of fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The surface and interfacial tension reduction performances of three obtained ionic surfactants were systematically investigated. And the results confirmed all the resultant surfactants could effectively reduce the surface and interfacial tension of the solution, and the CMC values were all determined approximately to 0.1 mg/mL. Meanwhile, three surfactants exhibit relatively low Krafft temperatures (below 6 ℃) and good wettability to oil-wetted surface. To further explore their promising applications, HPEanionic was proposed for use as a stabilizer in emulsion polymerization. Dynamic light scattering (DLS) measurements as well as transmission electron microscope (TEM) observation confirmed well-defined latex was obtained indeed. Moreover, as compared to latex synthesized by using the traditional small molecule compound surfactants, latex synthesized using HPEanionic as stabilizer exhibit improved tolerance to salinity. This beneficial result is probably caused by the special hyperbranched structure of HPEanionic, which contributes both electrostatic repulsion and steric hindrance drive force for the stabilization of latex particles.

On the association between poly(vinyl alcohol) and sodium dodecyl sulfate and its effect on liquid–liquid interfacial tension: A mathematical model

AbstractAssociation between poly(vinyl alcohol‐co‐vinyl acetate) copolymer (PVA) and sodium dodecyl sulfate (SDS) was studied experimentally and theoretically. It was found that, for the ethyl acetate‐aqueous phase interface in which PVA was previously adsorbed, the interfacial tension (γ) increases abruptly to a maximum and then exhibits a relatively mild decay with the addition of SDS to the aqueous phase. The theoretical results indicate that vinyl acetate (VAc) segments determine γ. However, for relatively low concentrations of SDS (CSDS), this latter plays a major role because through its association with the VAc segments it modulates the extent to which PVA is adsorbed at the interface, indirectly determining the value of γ. As CSDS approaches to the CMC value for SDS, its influence on γ decreases because SDS tends to self‐assembly rather than associates with VAc. These model predictions are consistent with experimental findings reported in the literature.

Thermo/pH dual-responsive micelles based on the host\u2013guest interaction between benzimidazole-terminated graft copolymer and \u03b2-cyclodextrin-functionalized star block copolymer for smart drug delivery

Novel temperature and pH dual-sensitive amphiphilic micelles were fabricated exploiting the host–guest interaction between benzimidazole-terminated PHEMA-g-(PCL-BM) and β-CD-star-PMAA-b-PNIPAM. The fabricated graft copolymer had a brush-like structure with star side chains. The micelles were utilized as dual-responsive nanocarriers and showed the LCST between 40 and 41 °C. The acidic pH promoted the dissociation of the PHEMA-g-(PCL-BM: β-CD-star-PMAA-b-PNIPAM) micelles. DOX.HCl was loaded into the core of the micelles during self-assembly in an aqueous solution with a high encapsulation efficacy (97.3%). The average size of the amphiphilic micelles was about 80 nm, suitable size for the enhanced permeability and retention effect in tumor vasculature. In an aqueous environment, these micelles exhibited very good self-assembly ability, low CMC value, rapid pH- and thermo-responsiveness, optimal drug loading capacity, and effective release of the drug. The biocompatibility was confirmed by the viability assessment of human breast cancer cell line (MCF-7) through methyl tetrazolium assay. DOX-loaded micelles displayed excellent anti-cancer activity performance in comparison with free DOX.Graphical

Mixed Micellization, Thermodynamic and Adsorption Behavior of Tetracaine Hydrochloride in the Presence of Cationic Gemini/Conventional Surfactants.

In this approach, tensiometry and UV-visible techniques are used to determine the effect of cationic gemini and conventional surfactants on tetracaine hydrochloride (TCH), an anesthetic drug. We have estimated micellar, interfacial, and energetic constraints. To gain a deep understanding of their mixed association behavior, the outputs were examined using different theoretical models. The critical micelle concentration for single and mixed amphiphiles was estimated. The cmc values of mixed amphiphiles were found between the individual amphiphiles due to strong attractive interaction (synergism) between the components after mixing. The non-ideal behavior of mixtures was confirmed by the larger values of ideal cmc than the experimental cmc values. The negative values of interaction parameter (β) and values of activity coefficients less than unity indicate strong synergistic interaction between drug and surfactant. The stability of the mixed systems is demonstrated by the negative Gibbs free energy of micellization and excess free energy of micellization. In contrast to a single chain surfactant, a double chain surfactant (gemini) exhibits better interactions with the drug. Spectral measurements (UV-visible spectra) were used to monitor the binding of the drug with surfactant (conventional as well as gemini). Studying these mixed aggregates could help to optimize their compositions and find synergistic properties between TCH monomers and surfactants.

One-Pot Synthesis of Amphiphilic Biopolymers from Oxidized Alginate and Self-Assembly as a Carrier for Sustained Release of Hydrophobic Drugs.

In this paper, we developed an organic solvent-free, eco-friendly, simple and efficient one-pot approach for the preparation of amphiphilic conjugates (Ugi-OSAOcT) by grafting octylamine (OCA) to oxidized sodium alginate (OSA). The optimum reaction parameters that were obtained based on the degree of substitution (DS) of Ugi-OSAOcT were a reaction time of 12 h, a reaction temperature of 25 °C and a molar ratio of 1:2.4:3:3.3 (OSA:OCA:HAc:TOSMIC), respectively. The chemical structure and composition were characterized by Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR), X-ray diffraction (XRD), thermogravimetry analyser (TGA), gel permeation chromatography (GPC) and elemental analysis (EA). It was found that the Ugi-OSAOcT conjugates with a CMC value in the range of 0.30–0.085 mg/mL could self-assemble into stable and spherical micelles with a particle size of 135.7 ± 2.4–196.5 ± 3.8 nm and negative surface potentials of −32.8 ± 0.4–−38.2 ± 0.8 mV. Furthermore, ibuprofen (IBU), which served as a model poorly water-soluble drug, was successfully incorporated into the Ugi-OSAOcT micelles by dialysis method. The drug loading capacity (%DL) and encapsulation efficiency (%EE) of the IBU-loaded Ugi-OSAOcT micelles (IBU/Ugi-OSAOcT = 3:10) reached as much as 10.9 ± 0.4–14.6 ± 0.3% and 40.8 ± 1.6–57.2 ± 1.3%, respectively. The in vitro release study demonstrated that the IBU-loaded micelles had a sustained and pH-responsive drug release behavior. In addition, the DS of the hydrophobic segment on an OSA backbone was demonstrated to have an important effect on IBU loading and drug release behavior. Finally, the in vitro cytotoxicity assay demonstrated that the Ugi-OSAOcT conjugates exhibited no significant cytotoxicity against RAW 264.7 cells up to 1000 µg/mL. Therefore, the amphiphilic Ugi-OSAOcT conjugates synthesized by the green method exhibited great potential to load hydrophobic drugs, acting as a promising nanocarrier capable of responding to pH for sustained release of hydrophobic drugs.

Morphology of Ionic Micelles as Studied by Numerical Solution of the Poisson Equation.

The existing concepts of the ionic micelle structure were specified. It was noted that the composition of dispersed phase particles in a liquid dispersion medium should necessarily include adsorbed counterions rigidly bound to these particles. By numerical solution of the Poisson equation for the two most often used approximations, the Poisson–Boltzmann (PB) model and the Jellium-approximation (JA), the electric potential decay from the Stern potential of dispersed phase particles was defined. A new methodological approach to analyze the reaction of micelle potential decay based on small variability of the CMC value was proposed. It made possible to determine the dimension parameter, which in the presence of weak thermal effects approximately corresponds to the micelle hydrodynamic radius, and to calculate the electrokinetic potential of micelles. The results of theoretical calculations were compared with our previous experimental data on the thickness of the SDS micelle hydrophilic layer obtained by SAXS. A good agreement between the calculated and measured values was obtained, and it was noted that for low concentrations the experimental values are more correctly described by the PB model, but for concentrations greater than 100 mM the JA model is more preferable. It was found that the slipping plane is located near the outer Stern plane and is separated from it only by a few molecular layers of water. The influence stronger than the thermal one can shift the slipping plane closer to the micelle core. Accordingly, the smallest hydrodynamic micelle size is determined by the outer Stern plane. The results of our work allowed us to conclude that the micelle is not something soft and watery, but according to its specified structure, it is a more solid-like particle than was previously assumed. The proposed approach can be extended to investigate other effects of a physicochemical nature, in particular, those observed with the addition of an external electrolyte or nanoparticles.

Synthesis, interfacial activity and rheological properties of low interfacial tension viscoelastic Gemini surfactants

In order to develop a special surfactant that is suitable for improving oil recovery in low permeability reservoirs, and simultaneously meet the requirements of effectively improving sweep efficiency, displacement efficiency and good injectability, a series of new Gemini surfactants (GAC-3m, m = 14, 16, 18) were synthesized and characterized by FTIR and 1 HNMR. The surface activity, interfacial activity, thickening properties and viscoelasticity of GAC-3m solution were systematically studied. The mechanism of viscosity and elasticity enhancement were also discussed. The results showed that with increasing the carbon number of hydrophobic chain, the surface activity and interface activity of GAC-3m surfactant increased first and then decreased, the viscosity and elasticity gradually increased. The micelle microstructures changed from sheet to network-like, and the structural morphology was gradually complete and compact, which made the viscosity and elasticity of the GAC-3m surfactant solution increase. GAC-3m exhibit fascinating surface activity, interfacial activity and low values of CMC (<4.5 × 10 −4 mol/L), which is conducive to the formation of micelle structure at low concentration. The 0.5% GAC-316 solution can substantially reduce the oil-water interfacial tension to ultralow values (10 −3 mN/m), and also possess attractive viscosity (18.58 mPa s) and viscoelastic properties (tanδ = 0.5 < 1). In accordance with the experimental studies, the novel surfactants (GAC-3m) are a kind of low interfacial tension viscoelastic Gemini surfactant, promising in enhancing the recovery of low permeability reservoirs. The insights gained from this study contribute to enriching the theoretical research of the viscoelastic Gemini surfactant and promote the applications of low interfacial tension viscoelastic Gemini surfactant in the recovery of heterogeneous low permeability reservoirs fields. • A series of new carboxylate Gemini surfactants GAC-3m were synthesized and characterized by FTIR and 1 HNMR. • The interfacial activity, thickening property, viscoelasticity and thickening mechanism of GAC-3m solution were studied. • GAC-3m exhibit fascinating surface activity and low CMC, which is conducive to forming micelle structure at low concentration. • GAC-316 can reduce the interfacial tension to ultralow values, and also possesses attractive viscosity and viscoelasticity. • GAC-3m possess favorable shear-thinning behavior which is desirable for improving mobility control during EOR processes.

Synthesis, aggregation behavior and drug-binding interactions of fatty acid-imidazolium-based surface-active ionic liquids

The renewable fatty acid-based surface-active ionic liquids (SAILs) containing ethyl-substituted imidazolium head groups were prepared and structurally analyzed by Fourier transform infrared spectroscopy (FTIR), 1HNMR and 13CNMR spectroscopy. The products were named as; 3-ethyl-1-(2-dodecanoyl oxy) ethylimidazolium bromide [C12Eeim]Br, 3-ethyl-1-(2-tetradecanoyl oxy) ethylimidazolium bromide [C14Eeim]Br and 3-ethyl-1-(2-hexadecanoyl oxy) ethylimidazolium bromide [C16Eeim]Br. The critical micelle concentration (cmc) values of the three SAILs have been evaluated using conductivity measurements, probe-less UV–visible spectroscopy and fluorescence spectroscopy. The obtained cmc values were compared with the earlier reported non-functionalized SAILs such as [Cnmim]Br and [Cneim]Br where n = 12, 14, 16. The values were found to be 3–9 times lower mainly due to the presence of ester chain and also ethyl substituted imidazole ring. Thermodynamic parameters were evaluated by conductivity data at three different temperatures. Further, the aggregation behavior of SAILs with anesthetic drug, lidocaine hydrochloride (LC) has been studied using fluorescence. The fluorescence and UV–visible studies showed strong synergistic interactions operating between SAILs and drug molecules involving H bonding and cation-π interactions. The interactions grew stronger with the elongation of SAIL-chain length (12–16C). Dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements suggested the formation of vesicles in SAIL-LC mixtures. These studies may thus offer an effective candidate which would serve as vectors for drug molecules in terms of their enhanced solubilization, permeability and target-specific delivery.

Carbon mineralization potential of non-edible oil-seed cakes at different composting stages in soil

Non-edible oil-seed cakes of neem, madhuca and simarouba were subjected to natural decomposition by simple pit method in CR design during 2020–21 at UAS, GKVK, Bangalore. The physicochemical parameters temperature, pH, EC, mineral nutrients, lignin contents and phytotoxicity of oil-seed cakes during decomposition were determined at 30 days intervals for 90 days. Simultaneously, samples were also studied for the C-mineralization pattern by measuring CO2-C evolution during 60 days of the aerobic incubation experiment. The first-order kinetic model was used to describe the C-mineralization and calculate potentially mineralizable C. The decomposition of oil-seed cakes led to an increase in mineral nutrients and a decrease in lignin content and toxicity. After 60 days of the addition of soil with oil-seed cakes at different stages of compost, the cumulative C-mineralization occurred in the order neem&lt;madhuca&lt;simarouba. The kinetic model suggested the presence of potentially mineralizable C (C0) in the undecomposed simarouba oil-seed cake than in the neem and madhuca. This C0 decreased at 90 days of composting in all oil-seed cakes. The NMC was high in undecomposed oil-seed cakes in the order S-0&gt;M-0&gt;N-0. The CMC value of mature compost (90 days) was lower in neem and simarouba (6%) than in madhuca oil-seed cakes (22%). The low C-mineralization potential of raw and composted neem oil-seed cake suggested its superiority in the improvement of SOC. However, complete composting of oil-seed cakes of madhuca and simarouba was necessary for C-sequestration.

Characterization of Lipopeptides Biosurfactants Produced by a Newly Isolated Strain Bacillus subtilis ZNI5: Potential Environmental Application

Aiming the production of lipopeptides biosurfactants (BioS), we isolated a new strain identified as Bacillus subtilis ZNI5 from a hydrocarbon contaminated soil. Lipopeptides purification by anionic exchange chromatography and identification by Reverse Phase High Performance Liquid Chromatography–Mass Spectrometry (RP-HPLC–MS) permitted the selection of different homologues divided into four families. The first family corresponds to Surfactin isoforms with molecular weights of 1007, 1021 and 1035 Da; the second family correspond to Iturin isoforms with molecular weights of 1028, 1042 and 1056 Da; the third family correspond to a single isoform called Licheniformin with molecular weight of 1410 and the fourth family correspond to newly identified isoforms named Inesfactin with molecular weights of 973 and 987 Da. Regarding the functional properties of the ZNI5 BioS, it was characterized as a powerful surface-active agent that decreases the Surface Tension of water from 72 mN/m to about 32 mN/m with a CMC value of 350 mg/L more efficient than chemical surfactants (Triton X100; CTAB and SDS). Moreover, it has the capacity to disperse oil to about 80 mm at a concentration of 800 mg/L showing close efficiencies to the listed chemical surfactants. In addition, the physic–chemical characterization of the surface activities of ZNI5 BioS showed great thermal, pH and salts activity and stability enabling its use in the bioremediation fields and for diverse industrial applications.

Binary system of alkyl polyether carboxylate and quaternary ammonium with ultra-low interfacial tension at high temperature and a wide range of salinity

A novel formula of anionic surfactants with propoxy (PO) and ethoxy(EO) groups and cationic surfactants was developed and temperature and salt resistance performance of the formula has been studied with both model oil and crude oil. An obvious synergistic effect was evidenced by CMC values and interaction parameters of nonylphenol polyether carboxylate, hexadecyltrimethylammonium chloride and their mixtures. Effect of molar ratio of anionic surfactant and cationic surfactant, temperature, salinity, concentration and oil-water ratio on phase behavior and interfacial tension were investigated systematically. The results demonstrate that ultra-low interfacial tension and excellent phase behavior were obtained at temperature up to 120 °C and a wide range of salinity, which shows promising for enhanced oil recovery.

Experimental and DFT studies on micellization features of anionic surface active ionic liquid and nonionic surfactant mixtures: Effect of imidazolium cations

The micellization characteristics of nonionic surfactant (Triton TX-100, p-octyl polyethylene glycol phenyl ether) and two anionic surface active ionic liquids (SAILs) were investigated by surface tension measurements, steady state fluorescence tests, dynamic light scattering (DLS), HNuclear magnetic resonance, and density functional theory (DFT) calculations. The anionic SAILs were 1-ethoxycarbonyl-3-methylimidazolium dodecyl sulfate ([Etmim][C12H25SO4]) and 1-ethoxycarbonyl-3-butylimidazolium dodecyl sulfate ([Etbim][C12H25SO4]). CMCmix values of SAIL/TX-100 mixtures were between CMC values of individual surfactants, and decreased with the increase of the molar fraction of TX-100. The negative β values (interaction parameter) of SAIL/TX-100 mixtures indicated good synergistic effect amid SAIL/TX-100 mixtures. [Etbim][C12H25SO4] showed stronger attractive interactions than [Etmim][C12H25SO4] during SAIL/TX-100 micellization. The mixed micelles contained a larger molar fraction of TX-100 over the entire range of composition. At same molar fraction of TX-100, X1 values of [Etbim][C12H25SO4]/TX-100 mixtures were lower than those of [Etmim][C12H25SO4]/TX-100 mixtures. With addition of SAIL, the particle sizes of SAIL/TX-100 micelles decreased. With the increase of SAIL concentrations, the particle sizes of SAIL/TX-100 micelles decreased. In presence of SAILs ([Etmim][C12H25SO4] or [Etbim][C12H25SO4]), all protons of TX-100 moved downfield. The chemical shifts of protons in [Etmim][C12H25SO4] or [Etbim][C12H25SO4] slightly moved upfield. DFT simulations demonstrated the presence of hydrogen bonds between the imidazolium cation of SAILs and EO chain of TX-100, and between sulfate anion group(-SO4-) of SAILs and hydrogen atoms in TX-100. The information will shed light on the rapid screening of novel anionic SAIL/surfactant mixtures for practical applications.

The ternary mixed micelle of tween 20- sodium deoxycholate- sodium cholate: The molar excess thermodynamic potencials

Micellisation of the ternary mixture Tween-20, sodium deoxycholate and sodium cholate is examined in the temperature interval T = (278.15–318.15) K. Experimentally are determined: critical micelle concentration (cmc) of ternary mixtures of examined surfactants and critical micelle concentrations of binary mixtures and monocomponent surfactants. Based on the Regular solution theory, the parameters of the ternary mixed micelle are calculated from the measured cmc values. The non-ionic surfactant dominates in the amount of ternary mixed micelle. Both bile acid anions in the binary mixed micelle with Tween 20 have synergistic interactions, i.e. have negative interaction coefficients of similar magnitudes. However, sodium deoxycholate is a bile salt which, regardless of the composition of the initial ternary mixture of surfactants, represents the main amount of bile salt in the ternary mixed micelle. The entry of bile acid anions into the ternary micellar pseudophase determines which bile acid anion can reduce the total Gibbs energy of the aqueous surfactant solution, rather than their contribution to the thermodynamic stabilization of real ternary mixed micelles, relative to the hypothetical ideal state of the same micelle.

Transition from antagonistic to synergistic interaction in mixed micellar system by increase in alkyl chain length of alkyl trimethylammonium bromide

Herein, the electrical conductivity technique used to measure the critical micelle concentration (cmc) for pure cationic surfactants (Dodecyl/cetyltrimethylammonium bromides) and phenothiazine drug (Promethazine hydrochloride), as well as their different mole fractions in 10−3 ​mol/kg 1-methyl-3-octylimidazolium chloride (C8mim.Cl) at different temperatures. By using the cmc values the regular solution theory used to evaluate the micellar mole fraction for DTAB/CTAB-PMT mixed systems. The clint's model used to calculate the ideal critical micelle concentration (cmc∗) that helps to evaluate the ideal micellar mole fraction for studied mixed systems, both explain the deviation from ideality. In addition, interaction parameter βm helps to confirm the nature of interaction (either antagonistic or synergistic) for the studied systems. The calculated parameters confirm a transition in the binding nature from antagonistic to synergistic with the increase in alkyl chain length of cationic surfactant i.e., component of the binary mixed system. The ease of micellization for the studied systems discussed by the standard Gibb's energy of micellization (ΔGm0), as well as the standard enthalpy and standard entropy of micellization were (ΔHm0) and (ΔSm0), respectively to discuss the stability of the studied systems.