Mixtures Of Anionic Surfactants Research Articles

Revealing New Structural Insights from Surfactant Micelles through DLS, Microrheology and Raman Spectroscopy

The correlation between molecular changes and microstructural evolution of rheological properties has been demonstrated for the first time in a mixed anionic/zwitterionic surfactant-based wormlike micellar system. Utilizing a novel combination of DLS-microrheology and Raman Spectroscopy, the effect of electrostatic screening on these properties of anionic (SLES) and zwitterionic (CapB) surfactant mixtures was studied by modulating the NaCl concentration. As Raman Spectroscopy delivers information about the molecular structure and DLS-microrheology characterizes viscoelastic properties, the combination of data delivered allows for a deeper understanding of the molecular changes underlying the viscoelastic ones. The high frequency viscoelastic response obtained through DLS-microrheology has shown the persistence of the Maxwell fluid response for low viscosity solutions at high NaCl concentrations. The intensity of the Raman band at 170 cm−1 exhibits very strong correlation with the viscosity variation. As this Raman band is assigned to hydrogen bonding, its variation with NaCl concentration additionally indicates differences in water structuring due to potential microstructural differences at low and high NaCl concentrations. The microstructural differences at low and high NaCl concentrations are further corroborated by persistence of a slow mode at the higher NaCl concentrations as seen through DLS measurements. The study illustrates the utility of the combined DLS, DLS-optical microrheology and Raman Spectroscopy in providing new molecular structural insights into the self-assembly process in complex fluids.

Enhanced solubilization and desorption of pyrene from soils by saline anionic–nonionic surfactant systems

• Saline surfactant shows lower CMC values than fresh surfactant. • The lower β values of saline surfactants, the higher pyrene solubilization. • STPP reduces surfactant sorption onto soil and enhances pyrene desorption. This study investigates the influence of salinity on micellar behavior, enhanced solubilization and desorption of pyrene within single and mixed saline anionic–nonionic surfactants. Various interaction parameters linked to the micellarization and solubilization process have been correlated through theoretical treatments to quantify micellar characteristics and solubilization capabilities of the systems. Results show that the experimental critical micelle concentration ( CMC ) values of the saline system were lower than that of non-saline system, indicating more attractive interactions of individual surfactants and higher stability of mixed micelles in the presence of salts. Pyrene solubility in saline surfactant solutions exceeded that in a non-saline solution. Less electrostatic repulsion of saline mixed micelles may be responsible for the reduced CMC of the mixed micelles, the increase of molar solubilization ratio ( MSR ) and micelle–water partition coefficient ( K m ). The saline micelles enhanced desorption of pyrene from kaolin-rich soil, and the pyrene desorption increased with the increase of salinity. Furthermore, the presence of salinity reduced the sorption of surfactant onto kaolin-rich soil; e.g. from 15.34 to 11.07 mg of surfactant/g of soil at a mass ratio of 5:5 mixture of anionic and nonionic surfactants. The results of this study provide new insights for estimating the utility of mixed surfactants treatments for soil remediation.

Detergency of Vegetable Oils and Semi‐Solid Fats Using Microemulsion Mixtures of Anionic Extended Surfactants: The HLD Concept and Cold Water Applications

AbstractIn spite of the increasing interest in cold temperature detergency of vegetable oils and fats, very limited research has been published on this topic. Extended surfactants have recently been shown to produce very promising detergency with vegetable oils at ambient temperature. However, the excessive salinity requirement (4–14 %) for these surfactants has limited their use in practical applications. In this work, we investigated the mixture of a linear C10–18PO–2EO–NaSO4 extended surfactant and a hydrophobic twin‐tailed sodium dioctyl sulfosuccinate surfactant for cold temperature detergency of vegetable oils and semi‐solid fats. Four vegetable oils of varying melting points (from −10 to 28 °C) were studied, these were canola, jojoba, coconut and palm kernel oils. Anionic surfactant mixtures showed synergism in detergency performance compared to single surfactant systems. At temperatures above the melting point, greater than 90 % detergency was achieved at 0.5 % NaCl. While detergency performance decreased at temperatures below the melting point, it was still superior to that of a commercial detergent (up to 80 vs. 40 %). Further, results show that the experimental microemulsion phase behaviors correlated very well with predictions from the hydrophilic–lipophilic deviation concept.

Solubility enhancement of anthracene and pyrene in the mixtures of a cleavable cationic gemini surfactant with conventional surfactants of different polarities

Schematic representation for solubilization of the PAHs in mixed micelles of ester-linked cationic gemini with conventional surfactants. • An ester-containing gemini surfactant of lower toxicity was used for the study. • Interaction of 12-E2-12 with erythrocytes shows less toxicity than other surfactants. • PAHs solubilization performed in equimolar gemini-conventional surfactant mixtures. • Aqueous solubility of PAHs is increased for all the pure/mixed surfactant systems. • Solubility enhancement of pyrene is higher than anthracene. In this study, the solubilization of anthracene and pyrene was investigated in micellar solutions of ethane-1,2-diyl bis( N , N -dimethyl- N -dodecylammoniumacetoxy) dichloride (C 12 H 25 (CH 3 ) 2 N + (CH 2 COOCH 2 ) 2 N + (CH 3 ) 2 C 12 H 25 ·2Cl − , 12-E2-12) and its equimolar binary mixtures of conventional cationic, anionic and nonionic surfactants in water. Critical micelle concentration ( cmc ) and other physicochemical parameters were determined by the surface tension and conductivity measurements at 30 °C. Much lower cmc value was obtained for 12-E2-12 than the corresponding monomeric surfactant dodecyltrimethylammonium chloride (DTAC). Lower experimental cmc than the ideal cmc and the negative interaction parameters imply synergistic interaction between the surfactants in the binary solutions. Order of solubilization capacity of the pure/mixed surfactant micelles, for anthracene and pyrene, are not the same. Among the pure surfactants, Brij 58 has highest and SDBS has least efficiency for dissolution of the solutes. The mixed systems 12-E2-12 + SDS and 12-E2-12 + Brij 58 have highest dissolution power for anthracene and pyrene, respectively. Solubility enhancement was observed for both the solutes in the equivalent binary mixtures of the dicationic gemini 12-E2-12 with the anionic conventional surfactants SDS and SDBS. To determine the toxicity of 12-E2-12 and to quantify its interaction with erythrocytes, we have performed the hemolytic assessment. As regards the hemolytic activity and biodegradability test, 12-E2-12 is less toxic and readily biodegradable.

Physicochemical Properties of Amphiphilic Drug and Anionic Surfactant Mixtures: Experimental and Theoretical Approach

Herein, we have reported the mixed micelle formation of amphiphilic phenothiazine drug promethazine hydrochloride (PMT) and anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOT) mixtures at different compositions and temperatures (288.15, 293.15, 298.15, 303.15, and 308.15 K). A conductometric method is used to evaluate the critical micelle concentration (CMC) of binary mixtures. An attractive interaction between PMT and AOT mixed systems was indicated by the experimental and ideal critical micelle concentration (CMC and CMCid) values. The micellar mole fraction of anionic surfactant (, , , and ) was evaluated by different proposed models, and they prove the greater contribution of AOT in mixed micelle and increase with the increase in AOT concentration. Activity coefficients (f 1 and f 2) calculated by all recommended models were found to be always less than unity, signifying nonideality in the mixed systems. Different thermodynamic parameters have also been evaluated using the respective CMC values as a function of temperature. values were always found to be negative for all the systems; however, for pure drug as well as PMT–AOT mixed systems is negative at lower temperatures and positive at higher temperatures. The values are positive at all temperatures but their magnitude is higher at T = 303.15 K and above.

Experiment and simulation of the simultaneous removal of organic and inorganic contaminants by micellar enhanced ultrafiltration with mixed micelles

ABSTRACTLead, chromium, and chlorobenzene (CB) were removed simultaneously by micellar enhanced ultrafiltration with a mixture of anionic and nonionic surfactants. The process parameters, including the molar ratio of the nonionic surfactant to the ionic surfactant (α), surfactant to metal ion (S/M) molar ratio, applied pressure, and inlet flow rate, were investigated. As α was varied from 0 to 1.5, the rejection of the metal ions increased. The optimum α value was 0.5. The permeate flux decreased by 28% with increasing α from 0 to 1.5. The S/M ratio was optimized at 10 in the presence of CB. The addition of CB increased the rejection of surfactants and decreased the metal‐ion rejection. The effect of the applied pressure and inlet flow were studied and found to be optimum at 1 bar and 150 mL/min, respectively. The optimized parameters were applied to the steady‐state process. The multiple‐solute model was applied to the steady‐state data. The relative error for solute rejection was varied from 5 to 9%, and the relative error for flux was 5%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41435.

Dynamic interfacial tensions of binary nonionic–anionic and nonionic surfactant mixtures at water–alkane interfaces

The influences of nonionic surfactant on interfacial properties of anionic–nonionic surfactant against alkanes are studied by measuring the dynamic interfacial tension (IFT). The surfactants chosen are fatty alcohol polyoxyethylene carboxylate (C12EO3C) and fatty alcohol polyoxyethylene (C12E3) with various counterions, Na+, Mg2+, and Ca2+. On the basis of our experimental results, one can find that the addition of nonionic surfactants C12E3 could achieve an ultralow IFT value at some specific alkane carbon numbers under NaCl condition and the obvious synergistic effect on reducing IFT can be observed during all experimental alkane carbon numbers. However, for MgCl2 systems, the ultralow IFT values can be achieved by pure C12EO3C solutions and one can observe synergistic effect and antagonistic effect on IFTs at higher and lower alkane carbon numbers respectively by adding nonionic surfactant. On the other hand, for CaCl2 systems, the addition of 0.05% C12E3 shows the same influence on the IFTs as that of NaCl systems, while the similar effect as that of MgCl2 systems will be observed when adding 0.1% C12E3. An interfacial model combined two mechanisms, controlling hydrophilic–lipophilic balance and forming mixed adsorption film, responsible for varying IFT has been provided based on the difference of ion radius. By adding nonionic surfactant, the mechanisms of forming mixed adsorption film and controlling hydrophilic–lipophilic balance play crucial roles in effecting IFTs for NaCl systems and MgCl2 systems, respectively. Moreover, for CaCl2 systems, the responsible mechanism of forming mixed adsorption film will change into controlling hydrophilic–lipophilic balance with the increase of nonionic surfactant concentration.

γ-ray synthesis and size characterization of CdS quantum dot (QD) particles using flow and sedimentation field-flow fractionation (FFF)

Quantum dot (QD) emits light of characteristic wavelength which depends on the size of the QD particles, and thus the quality control of QD requires accurate determination of its size distribution. Field-flow fractionation (FFF) is a separation technique that is well suited for the characterization of colloidal particles. In this study, CdS-QD particles were synthesized by a simple one-step γ-ray irradiation. Then asymmetrical flow FFF (AsFlFFF) and sedimentation FFF (SdFFF) were tested as tools for characterization of the particles. The single crystallite size of CdS-QD was measured to be about 4nm by X-ray diffraction (XRD), UV-VIS absorption spectroscopy, and transmission electron microscopy (TEM). TEM images indicate that the particles were agglomerated to form larger secondary particles (~110nm). Effects of the various experimental parameters of FFF including the type of dispersing agent, the ionic strength of the carrier liquid, and strength of external field were investigated. It was found that, among the dispersing agents tested, a mixture of anionic and nonionic surfactants tends to give better elution of CdS particles than anionic or nonionic surfactants. Results suggest that FFF can provide some advantages over dynamic light scattering (DLS) or TEM for size characterization of CdS particles, and with a proper optimization, FFF (AsFlFFF or SdFFF) could become a useful tool for stability study as well as size analysis of nanoparticles such as the CdS particles synthesized in this study.

Nonaromatic Hydrotropic Cationic Ammonium Salts as a Rheology Modifier for an Anionic/Zwitterionic Surfactant Mixture

In this article, we report additive-induced micellar growth and rheology modification for mixtures of anionic (sodium dodecyl sulfate, SDS) and zwitterionic (N-alkylated glycine derivative, Empigen BB or EBB) surfactants. Two nonaromatic hydrotropic salts (hexyltrimethylammonium bromide, C6TAB, and/or dibutylenebis(dimethylbutylammonium bromide), 4-4-4) are used as novel additives to induce micellar growth in these systems. Nuclear magnetic resonance (NMR), photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), the Weissenberg effect, and rheology measurements were employed to assess mixed micelle formation, micellar growth, and rheology modifications. Finally, the manner in which the surfactants and hydrotropes self-assemble into aggregates has also been deduced from 2D NMR NOESY measurements. In this study, both hydrotropic ions have been found to contribute to similar structural modifications in the mixed micelles of the anionic and zwitterionic surfactants. However, the extent of the rheology modification in solution is found to be quite different when the gemini hydrotrope (4-4-4) versus the monomeric hydrotrope (C6TAB) is employed.

Controlling the Morphology of Membranes by Excess Surface Charge in Cat–Anionic Fluorinated Surfactant Mixtures

The segregation and phase sequence of semifluorinated cat-anionic surfactant membranes at different excess surface charges was investigated by freeze-fracture transmission electron microscope (FF-TEM), X-ray diffraction (XRD), and nuclear magnetic resonance (NMR). The thermal behavior of the membranes was evaluated by conductivity, rheology, and deuterium nuclear magnetic resonance ((2)H NMR). The experimental results show that the cat-anionic fluorinated surfactant mixtures can form faceted vesicles and punctured lamellar phase when there is excess surface charge. The cationic and anionic fluorinated surfactants are stiff in the membranes, like phospholipids in the frozen "crystalline" or "gel" phase. For the system with excess cationic surface charge, the gel-like faceted vesicles and punctured lamellae can transform into smooth-shaped vesicles at 65 °C. However, for the system with no excess charge or with excess anionic surface charge, no phase transformation occurs even at 90 °C. A model was established to demonstrate the mechanism of the formation and transition of the aggregates with different morphologies. The segregation-crystallization mechanism works well with other cosmotropic counterions from the Hofmeister series. The observations provide a better understanding of how to control the membrane morphology of the aqueous solutions of cat-anionic surfactant mixtures.

Stability of manganese dioxide by guar gum in the absence or presence of surfactants

Stability of the manganese dioxide (MnO2) suspensions by non-ionic guar gum (GG) in the absence or presence of the surfactants: anionic sodium dodecyl sulphate (SDS), cationic hexadecyltrimethylammonium bromide (CTAB) and non-ionic Triton X-100 (t-octylphenoxypolyethoxyethanol) and their equimolar mixtures (SDS/TX-100; CTAB/TX-100) was measured using turbidity. The obtained results of the manganese dioxide suspensions stability were discussed together with the adsorption data and with the data concerning the thicknesses of the adsorption layers. In order to gain more information about the structure of the electric double layer surface charge density and the zeta potential measurements were performed. The obtained results show that the addition of guar gum to the MnO2 suspensions increases MnO2 stability. The larger this increase is, the higher is the concentration of the polymer (concentration range 10–200 ppm). Moreover, the addition of single surfactants also causes the increase in the effectiveness of stabilizing the manganese dioxide suspensions. The reason for that is formation of multilayer complexes between the polymer and the surfactants. In such a system both the adsorption of polymer and the thickness of polymer adsorption layer increase. The greatest increase in the stability of MnO2/GG suspensions was provided by the mixture of anionic and non-ionic surfactants due to a strong synergistic effect. Also, mixing the polymer and two surfactants reduces the stability of the suspension.

Facile Directed Assembly of Hollow Polymer Nanocapsules within Spontaneously Formed Catanionic Surfactant Vesicles

Surfactant vesicles containing monomers in the interior of the bilayer were used to template hollow polymer nanocapsules. This study investigated the formation of surfactant/monomer assemblies by two loading methods, concurrent loading and diffusion loading. The assembly process and the resulting aggregates were investigated with dynamic light scattering, small angle neutron scattering, and small-angle X-ray scattering. Acrylic monomers formed vesicles with a mixture of cationic and anionic surfactants in a broad range of surfactant ratios. Regions with predominant formation of vesicles were broader for compositions containing acrylic monomers compared with blank surfactants. This observation supports the stabilization of the vesicular structure by acrylic monomers. Diffusion loading produced monomer-loaded vesicles unless vesicles were composed from surfactants at the ratios close to the boundary of a vesicular phase region on a phase diagram. Both concurrent-loaded and diffusion-loaded surfactant/monomer vesicles produced hollow polymer nanocapsules upon the polymerization of monomers in the bilayer followed by removal of surfactant scaffolds.

Behavior of Emulsification and Thickening of Crude Oil in Mixed Cationic and Anionic Surfactant Systems

We report the emulsification and thickening of crude oil using mixtures of cationic and anionic surfactants, which have high water content. The solubility of the mixed surfactants in simulated oil field water was improved by adjusting the surfactant molecular structure. The suitable concentration and mixing ratio ranges of various mixed systems were determined, and water in oil(W/O) lactescence with high water content was obtained. In addition, we studied the effects of temperature, pH value, ionic strength, and oil/water volume ratio on the emulsification and thickening processes. A series of mixed systems with good emulsification and thickening ability were determined and optimized. Notably, some of the systems increased the viscosity of the emulsion by up to 80 times. This has significance for the improvement of oil recovery.

Phase behavior and microstructures in a mixture of anionic Gemini and cationic surfactants.

We report in this work the phase behavior and microstructures in a mixture of an anionic Gemini surfactant, sodium dilauramino cystine (SDLC), and a conventional cationic surfactant, dodecyl trimethyl ammonium chloride (DTAC). Observation of the appearance shows that the phase behavior of the SDLC-DTAC mixed cationic surfactant system transforms from an isotropic homogeneous phase to an aqueous surfactant two-phase system (ASTP) and then to an anisotropic homogeneous phase with the continuous addition of DTAC. The corresponding aggregate microstructures are investigated by rheology, dynamic light scattering, transmission electron microscopy and polarization microscopy. It has been found that a wormlike micelle, in the isotropic homogeneous phase, occurs linear to the branch growth. The aggregate microstructures in the ASTP lower and upper phases are branched wormlike micelles and vesicles, respectively. The micelle transformed into a vesicle upon varying the phase volume percentage until a lamellar liquid crystal formed in the anisotropic homogeneous phase. The macroscopic phase behavior and microscopic aggregate structure are related to the understanding of the possible mechanisms for the above phenomena.

Swelling of Lamellar Gel from Catanionic Hydro- and Perfluoro-Carbon Surfactant Mixtures by Refractive-Index Matching

Bilayer swelling behavior of cationic and anionic surfactant mixtures in solution induced by adding glycerin was investigated. The measurements were performed a system, cationic tetradecyltrimetylammonium bromide (TTABr), and anionic sodium perfluorodecanoate (C9F19CO2Na) surfactant mixtures with their stoichiometric mole ratio being exactly 1 in aqueous solution. The non-precipitated phase of cationic and anionic hydro- and perfluoro-carbon surfactant mixtures being the mole ratio of 1:1 could be identified to be lamellar gel phase, which was characterized by freeze-fracture transmission electron microscopy (FF-TEM) and x-ray diffraction (XRD) measurements. Deuterium nuclear magnetic resonance (2H NMR) and rheology were used to characterize the phase transition from the lamellar gel to smaller vesicles. Phase transition from lamellar gel to smaller vesicles can be induced by adding glycerin to replace water. The addition of glycerin lowers the turbidity of the dispersion and swells the interlamellar distance between bilayers, which could be explained by matching of refractive index between solvent and bilayers.

Fragrance solubilization in temperature insensitive aqueous microemulsions based on synergistic mixtures of nonionic and anionic surfactants

Well-defined tetraethylene glycol monooctylether (C8E4) and its commercial polydispersed counterpart (Dehydol® O4) were used to solubilize fragrances. Addition of small amounts (≤1wt.%) of the ionic surfactants, sodium dodecylsulfate (SDS) or sodium lauryl ether sulfate (SLES), permits the formulation of temperature insensitive fragrance in water microemulsions. The investigation of the pseudo-ternary surfactants/β-pinene/water systems allows the determination of the optimum temperature T* as well as the assessment of the efficiency of the surfactant mixtures to solubilize β-pinene. A mixture of Dehydol O4 and SDS (9/1wt.%) can solubilize 6.5wt.% of β-pinene in water within the temperature range of 25–80°C. This synergistic formulation was also applied to the solubilization of p-cymene, the essential oils pinus pinaster and pinus sylvestris and a true fragrant mixture composed of 9 terpenes and terpenoids in dipropylene glycol.

Fabrication of positively charged catanionic vesicles from ion pair amphiphile with double-chained cationic surfactant

In this study, a pseudodouble-chained ion pair amphiphile, hexadecyltrimethylammonium-dodecylsulfate (HTMA-DS), was prepared from a mixture of cationic surfactant, hexadecyltrimethylammonium bromide, and anionic surfactant, sodium dodecylsulfate. Positively charged catanionic vesicles were then successfully fabricated from HTMA-DS with the addition of cationic surfactants, dialkyldimethylammonium bromide (DXDAB), including ditetradecyldimethylammonium bromide (DTDAB), dihexadecyldimethylammonium bromide, and dioctadecyldimethylammonium bromide (DODAB), with a mechanical disruption approach. The control of charge characteristic and physical stability of the catanionic vesicles through the variations of DXDAB molar fraction and alkyl chain length was then explored by size, zeta potential, and Fourier transform infrared analyses. It was found that the molecular packing and/or molecular interaction of HTMA-DS with DXDAB rather than the electrostatic repulsion between the charged vesicles dominated the physical stability of the mixed HTMA-DS/DXDAB vesicles. The presence of DTDAB, which possesses short alkyl chains, could adjust the packing of the unmatched chains of HTMA+ and DS− and promote the vesicle formation. However, the weak molecular interaction due to the short chains of DTDA+ could not maintain the vesicle structures in long-term storage. With increasing the alkyl chain length of DXDAB, it was possible to improve the vesicle physical stability through the enhanced molecular interaction in the vesicular bilayer. However, the long alkyl chains of DODAB unmatched with those of HTMA-DS, resulting in the vesicle disintegration in long-term storage. For the formation of stable charged catanionic vesicles of HTMA-DS/DXDAB, a good match in hydrophobic chains and strong molecular interaction were preferred for the vesicle-forming molecules.

Phase transition of sodium bis(2-ethyl-1-hexyl) sulfosuccinate and sodium deoxycholate mixtures in aqueous solutions

The aggregation behavior of two anionic surfactant mixtures, sodium bis(2-ethyl-1-hexyl) sulfosuccinate (AOT) and sodium deoxycholate (SDC), in aqueous solution was investigated at room temperature. The mixture aqueous solution goes through a series of phase transition from a planar lamellar Lα phase to an L1/Lα two-phase, and finally to the transparent isotropic solution with the increase in SDC molar fraction. The surface tension measurements show that the mixtures have synergistic surface activity. The small-angle X-ray scattering (SAXS) and 2H nuclear magnetic resonance (2H NMR), and freeze-fracture transmission electron microscopy (FF-TEM) clearly demonstrate a phase transition from lamellar structure to hexagonal structures with the addition of SDC to the AOT Lα phase. The rheological measurements show the highly viscoelastic property of the Lα phase formed by AOT, for which the viscosity decreases with the increase in the proportion of SDC because of the re-arrangement of the planar bilayers. The structure transition of AOT and SDC mixtures might be a result of the balance of the repulsive force between the negative headgroups of AOT and SDC, the hydrophobic interaction between the double chains of AOT and the steroid skeleton of DS−, and steric effect of DS−.

Research on the Micellar Dispersal Behaviors in Mixed Surfactant System by Cyclic Voltammetry

Cyclic voltammetry method was used to investigate the dispersal behaviors of micelles in mixed solutions of cationic surfactant CTAB (cetyltrimethyl ammonium bromide) and anionic surfactant SDS (sodium dodecyl sulfate) at 313 K using ferrocene as the probe. Voltammetric behaviors of ferrocene on the electrode were reversible, indicating the diffusion of ferrocene in the mixtures of cationic and anionic surfactants was controlled by the microstructures of the mixtures. The results showed that the anionic micellar diffusion coefficient initially decreased and then increased with CTAB content due to the structural transformation of micelles. However, the cationic micellar diffusion coefficient curve appeared a monotonous decreasing trend with the increase of the CTAB content in the experimental range, and the diffusion coefficient of cationic micelle was smaller than that of anionic micelle.

Phase property, composition and temperature-induced phase inversion of ATPS-C formed by aqueous cationic–anionic surfactant mixtures

Three quaternary ammonium surfactants, N-alkyl-N, N-2-dihydroxyethyl-N-methyl ammonium bromide (CnDHAB, n=12, 14, and 16) and sodium dodecyl sulfate (SDS) have been used to form aqueous two-phase systems of cationic–anionic surfactant mixtures with cationic surfactant in excess (ATPS-C). Densities, viscosities, interfacial tensions and ion concentrations of/between the two separate phases were measured and microstructures were observed as a function of temperature to elucidate the temperature effect on ATPS-C and the phase inversion. The density of the surfactant-concentrated phase decreases against the temperature faster than that of the dilute phase, which can lead to the phase inversion at a certain temperature. The ultralow interfacial tension between the separated phases can be determined, which exhibits a minimum near the phase inversion temperature. It is followed that the property differences between the separated phases are the lowest around the phase-inversion temperature. Composition analyses manifest that the inorganic ions transferring from the concentrated phase to the dilute phase with increasing the temperature. These transformations make main contributions to the change of density difference between the separate phases. Combining the results of viscosity measurement, dynamic light scattering (DLS), and transmission electron microscopy (TEM), it is evident that network structures and large aggregates are destroyed and smaller spherical micelles or vesicles can be observed in the concentrated phase with increasing the temperature. In the dilute phase, vesicles can be observed and most of the aggregates are irregular micelles especially at lower temperatures before the phase inversion occurs.