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The unique structure and macro-rheological properties make worm-like micelles an important basic system for surfactant applications, which are widely used in many fields and have received extensive attention from researchers. In this paper, α-olefin sodium sulfonate (AOS) and cocamidopropyl betaine (CAPB) were mixed in aqueous solution to prepare viscoelastic worm-like micelles, which can be observed by cryogenic-transmission electron microscopy (cryo-TEM). It was found that the concentration of AOS and temperature have a greater impact on the formation and rheological behavior of worm-like micelles. The typical characteristics of wormlike micelles were shown in the range of AOS concentration from 0.7 wt% to 1.7 wt%; when the temperature was too high, the worm-like micelles were destroyed. In addition, the surface tension, foaming property and wettability of AOS/CAPB mixed solutions with different ratios were studied. The two show excellent synergistic effect, in which electrostatic interaction is the decisive factor, which can provide basic data for practical applications. This work further enriches the basic theoretical research on the preparation of worm-like micelles from anionic-zwitterionic surfactant systems. [ABSTRACT FROM AUTHOR]

Sodium isotridecyl polyoxyethylene ether sulfate (iC13EOnS, n = 5, 7, and 9) with different ethylene oxide (EO) numbers were synthesized by SO3 membrane sulfation process for the first time. The effects of EO number on the equilibrium surface tension, dynamic surface tension, contact angle, and alkali/salt resistance of iC13EOnS were investigated. With the increase of EO consumption, γcmc increased, but the adsorption efficiency (pC20) of surfactant increased. The increase of EO number significantly improved the alkali resistance and salt resistance of iC13EOnS. Additionally, the influence of different electrolytes and their concentrations on the IFT between iCl3EOnS solution and n-decane was also studied. At the same salt concentration, iC13EOnS with shorter EO chains exhibited lower interfacial tension. These results show that the performance of the product can be adjusted by changing the number of EO groups. The study on the relationship between EO number and the performance of iC13EOnS in this article will help to improve the application efficiency of this surfactant. [ABSTRACT FROM AUTHOR]

The anionic-nonionic surfactants have attracted great interest due to its particular molecular structure. To compare the effect of anionic headgroup on the performance of anionic-nonionic surfactants, the adsorption behavior at air/water and oil/water interface, spreading performance and thermal stability of anionic-nonionic surfactants, sodium alkyl polyethylene oxide carboxylate (AE 3 C), sodium alkyl polyethylene oxide sulfate (AE 3 S), and sodium alkyl polyethylene oxide sulfonate (AE 3 SO), were investigated by surface tension, interfacial tension, contact angle techniques and thermogravimetric analysis. The results of static surface tension and interfacial tension show that the AE 3 C has the best interfacial activity. Adsorption process for surfactants concentration above cmc is a mixed diffusion–kinetic adsorption mechanism, and below cmc is diffusion-controlled mechanism. Spreading ability on paraffin films of the three surfactants decreases in the order AE 3 C > AE 3 S > AE 3 SO. The thermal stability is in the sequence of AE 3 C > AE 3 SO > AE 3 S. [ABSTRACT FROM AUTHOR]

surface tension, interfacial tension and emulsification of extended surfactants, sodium dodecyl polypropylene oxide sulfate (C 12 P m S, m = 4, 8 and 12) and sodium dodecyl polypropylene oxide–polyethylene oxide sulfate (C 12 P 8 E 2 S), were investigated. The influence factors such as propylene oxide (PO) number, calcium chloride (CaCl 2 ) concentration, and surfactant concentration were studied in detail. It was found that surface activity of C 12 P m S increases with the increase of number of PO units. The interfacial tension (IFT) between C 12 P m S solution and decane all reaches ultralow range (<10 −2 mN/m) at optimum NaCl concentration. Ultralow IFT between C 12 P 8 S solution and Shengli crude oil could be reached in a wide range of CaCl 2 concentrations without alkali. IFT between C 12 P 8 E 2 S solution and crude oil could reach ultralow value without alkali in a wide range of CaCl 2 concentrations and surfactant concentrations. For C 12 P 8 S and C 12 P 8 E 2 S, oil drop during the measurement of IFT was lengthened and broken in which IFT was below 10 −4 mN/m. Emulsion between crude oil and C 12 P m S solution could form in a wide range of CaCl 2 concentrations. Low IFT is not related to emulsion formation. However, ultralow IFT helps to increase the emulsion stability. [ABSTRACT FROM AUTHOR]

The equilibrium and dynamic surface tension of nonylphenol polyethylene oxides sulfonate (NPE n S, n = 3, 5 and 7) were investigated; and, the effect of electrolytes (NaCl, MgCl 2 and CaCl 2 ) on the interfacial tension between NPE n S solution and dodecane was discussed. It was found that the critical micelle concentration (cmc) of NPE n S is almost the same. The surface tension at cmc and minimum area per molecule increase with increasing the EO number. The time required to attain the equilibrium surface tension decreases with increasing surfactant concentration and the EO number. Adsorption process for NPE n S concentration above cmc is a mixed diffusion-kinetic adsorption mechanism. Interfacial tension between NPE n S solution and dodecane increases with the increase of EO number at studied electrolyte concentrations (NaCl concentration from 10 to 210 g/L, CaCl 2 and MgCl 2 concentration from 0.1 to 10 g/L). Most of IFT measured keeps in the order of 10 − 1 mN/m magnitudes in a wide range of electrolytes concentrations, which indicates that NPE n S is insensitive to electrolyte and suitable for co-surfactant in high salinity reservoirs. [ABSTRACT FROM AUTHOR]

Dialkylated diphenylether disulfonate with different alkyl chain lengths (C-DADS, n = 8, 10 and 12) has been synthesized by Friedel-Crafts alkylation of olefins (C, C and C) and diphenyl oxide, followed by sulfonation and neutralization with fuming sulfuric acid. Sulfated zirconia solid acids were prepared and used to catalyze the alkylation reaction. The structure of sulfated zirconia solid acids was identified by infrared spectroscopy. The title compounds were confirmed by infrared spectroscopy and electrospray ionization-mass spectrometry. Equilibrium surface tension measurements show that the critical micelle concentration (CMC) decreases with an increase in chain length, and the surface tension at CMC ( γ) of C-DADS is the lowest. The minimum area per molecule ( A) values of C-DADS increase, while the surface excess concentration ( Γ) values decrease with the increase of the alkyl chain length. C-DADS has the highest pC and CMC/C among C-DADS. [ABSTRACT FROM AUTHOR]

Three anionic surfactants of the monododecyl diaryl disulfonate type (MDDADS-n, n = 0, 1, 2) were synthesized. The structural characters of MDDADS-n surfactants were verified by electrospray ionization/mass spectrometry. The effect of the spacer group on the surface activity, salinity and hardness tolerance and mimic oil washing efficiency were investigated. The results showed that the critical micelle concentration (CMC), surface tension at CMC, C and the minimum area per molecule of the anionic surfactants increased when the spacer group length increased. There was less effect on mimic oil washing efficiency of MDDADS-n when the spacer group changed; meanwhile, they displayed higher mimic oil washing efficiency in salt solution (NaCl or CaCl) than that of sodium dodecylbenzenesulfonate (SDBS); all MDDADS-n surfactants showed much lower sensitivity to water hardness than SDBS, what would be beneficial to enhancing oil recovery in a high salinity oil field. [ABSTRACT FROM AUTHOR]

• A new surfactant was synthesized by inserting propoxy group after ethoxy group of aliphatic alcohol ether sodium sulfate. • The cmc of surfactants has a linear negative correlation with the appropriate amount of propoxy group. • The new surfactants have low foaming, salt resistance, strong emulsification resistance, and good wettability at high temperatures. In recent years, the Polyoxypropylene (PO) group has been introduced between the hydrophobic group and the polyoxyethylene (EO) group of traditional surfactants to enhance interfacial properties. However, literature on surfactants introducing PO chains between EO and hydrophilic groups remains scarce. In this study, three variants of natural alcohol polyoxyethylene polyoxypropylene ether sulfate (C 1214 E 3 P n S), each with different PO addition numbers, were synthesized from natural alcohol ether through sulfation and neutralization reactions. The adsorption behavior of C 1214 E 3 P n S with different PO addition numbers was investigated and compared to AES by measuring surface tension, dynamic surface tension, and contact angle. The results indicate that as the number of PO increases, both the critical micelle concentration and maximum adsorption capacity decrease. Additionally, pC 20 and the number of PO groups introduced in the surfactant show a linear negative correlation, indicating a decline in surfactant efficiency. Due to an adsorption barrier, C 1214 E 3 P n S is governed by a mixed diffusion-kinetics adsorption mechanism. According to the application performance of C 1214 E 3 P n S, as the number of PO increases, wettability and foam stability have decline, while emulsifying performance is significantly enhanced. In conclusion, surfactants such as C 1214 E 3 P n S do not favor adsorption at the solid–liquid interface, but enhance the properties at the oil–water interface. [ABSTRACT FROM AUTHOR]