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Nonylphenol ethoxylates (NPEOn), typically NPEO10, are the second popular nonionic surfactants that have been banned or restricted from use and production by Europe since 1990 due to their poor degradability and high genetic toxicity. The hypothesis of this work is that the nonylcyclohexanol ethoxylates (NCEOn) may possess similar interfacial properties but lower biotoxicity and better biodegradability compared with NPEOn according to their structures. To verify this and to find the optimal alternative of NPEO10, the interfacial properties of NCEOn were compared with the typical commercial ethoxylates nonionic surfactants, such as nonylphenol ethoxylated‐10 (NPEO10), alcohol ethoxylated‐9 (AEO9), secondary alcohol ethoxylated‐9 (SAE9), and isomeric alcohol ethoxylated‐9 (TO9). It is the NCEO7 that shows excellent emulsifying ability similar to that of NPEO10. NCEO11 performed stronger detergency than other assayed commercial nonionic surfactants. Additionally, NCEOn possessed lower biological toxicity to aquatic organisms. Hence, NCEOn could be considered as a green substitute for NPEOn in the assayed application fields. [ABSTRACT FROM AUTHOR]

To develop a convenient and reversible strategy for phase separation and re-emulsification of surfactant-based emulsions, we established a method for pH switching of emulsions formed from a pH-switchable anionic surfactant, potassium dodecyl seleninate (CSeOK). Upon acidification, CSeOK was protonated to give a precipitate of dodecyl seleninic acid (CSeOH); upon basification, CSeOH was neutralized restore CSeOK. The pH-switchable window of the emulsion thus obtained was a pH range of 7 to 8. Reversible changes in both interfacial tension by ~10.2 mN m, as well as the mechanical, steric, and/or electrical barriers formed by CSeOK at the interface of the oil-aqueous solution account for the fully reversible phase separation and re-emulsification of the CSeOK-based emulsions. A stable emulsion (i.e. the time needed to separate 1 mL of HO from 6 mL of emulsion at 25 °C is larger than 1 h) could be cycled at least 25 times when the pH was varied between 7 and 8. [ABSTRACT FROM AUTHOR]

In order to determine the structure-performance relationship of nonionic-zwitterionic hybrid surfactants, N, N-dimethyl- N-dodecyl polyoxyethylene ( n) amine oxides (CEOAO) with different polyoxyethylene lengths (EO, n = 1-4) were synthesized. For homologous CEOAO, it was observed that the critical micelle concentration (CMC), the maximum surface excess (Γ), CMC/ C, and the critical micelle aggregation number ( N) decreased on going from 1 to 4 in EO. However, there were concomitant increases in surface tension at the CMC ( γ), minimum molecular cross-sectional area ( A), adsorption efficiency (p C), and the polarity ([ I/ I]) based on the locus of solubilization for pyrene. The values of log CMC and N decreased linearly with EO lengthening from 1 to 4, although the impact of each EO unit on the CMC of CEOAO ( n = 1-4) was much smaller than that typically seen for methylene units in the hydrophobic main chains of traditional surfactants. Compared to the structurally related conventional surfactant N, N-dimethyl- N-dodecyl amine oxide (CAO), CEOAO ( n = 1-4) have smaller CMC, A, and CMC/ C, but larger p C, Γ, and N with a higher [ I/ I]. This may be attributed to the moderately amphiphilic EO ( n = 1-4) between the hydrophobic C tail and the hydrophilic AO head group. [ABSTRACT FROM AUTHOR]

Bioactive and biocompatible conjugated linoleic acid (CLA) has been only considered as a food or medicine ingredient due to its rare natural occurrence. In this work, the surface activities and pH-induced self-assembling behaviors of the semi-synthetic CLA molecules into micelles or vesicles were systematically investigated. First, the self-assembling of CLA was studied in detail, and it was found that aside from temperature and ionic strength, pH is the prominent factor affecting the self-assembling of CLA. Moreover, stable CLA ufasomes (unsaturated fatty acid liposomes) in uniform size were obtained by self-crosslinking of the CLA ufasomes, and the morphologies of the crosslinked CLA assemblies were recorded by transmission electron microscopy, which made known the pH-induced formation of the CLA ufasomes or the CLA micelles. The crosslinked CLA assemblies presented improved properties such as a higher calcium stability, a lower lime soap dispersing requirement and a better solubilization ability than that of the CLA molecules themselves or the pre-crosslinked linoleic acids. These investigations could be helpful for comprehensively understanding effects of environment factors on self-assembling behaviors of conjugated fatty acids and responsive polymerization of polymerizable surfactants. [ABSTRACT FROM AUTHOR]

The phenol-formaldehyde condensation reaction to synthesize a gemini precursor was renewed by using high efficient and environmentally benign resin catalysts instead of protonic acids, and the conversion, yield and selectivity of the reaction were all upgraded from the 60 % by the traditional way to over 90 % by the new way. Three alkylaryl sulfonate gemini surfactants were derived from the above gemini precursor by O-methylation, sulfonation and neutralization, that is, sodium salt of sulfonated bis(2-hydroxy-5-nonylphenyl)methane (SBHNM), sodium salt of sulfonated bis(2-hydroxy-5-dodecylphenyl)methane (SBHDM) and sodium salt of sulfonated bis(2-methoxy-5-nonylphenyl)methane (SBMNM). And their performances in aqueous solution were further investigated. The results show that the three gemini surfactants exhibit higher effectiveness and efficiency in surface tension reduction than a monomeric reference surfactant sodium dodecylbenzene sulfonate (SDBS). Furthermore their critical micelle concentration values are at least one order of magnitude lower than that of SDBS. It is also shown that O-methylation of the hydroxyl group in the gemini precursor is effective at improving the surface activity of the gemini surfactants, such as efficiency in surface tension reduction, foam stability and calcium stability. It is suggested that the synthesized hydrophobic skeleton could be a multi-purpose gemini precursor from which various gemini surfactants could be derived by further hydrophobic or hydrophilic modification. [ABSTRACT FROM AUTHOR]

Low-foam penetrating agents have been sought after for many industrial applications. In this paper, we were aiming at a low-foam penetrating agent with excellent wetting ability and hydrolysis resistance, various silicon-terminated penetrating agents were designed and synthesized starting from a popular commercial penetrating agent, octyl/decyl polyethylene oxide (OEO). All the products present much better low-foam performances than that of the precursor OEO. Statistically, multi-OEO substituted products present the best low-foam performance but a slightly weaker wetting ability. Except octyl/decyl polyethylene oxide trimethyl silicane, all the other five products maintain excellent wetting ability and show good hydrolysis resistance at neutral pH and ambient temperature. Di(octyl/decyl polyethylene oxide) dimethyl silicane is the preferred low-foam penetrating agent based on its structure-performance and cost, which reduced the foam volume of OEO from 75 to 4 mL (on the 100 mL volume base) at neutral pH and ambient temperature with a similar wetting ability. [ABSTRACT FROM AUTHOR]

Four diakylimidazolium ionic liquids, namely 1-alkyl-3-dodecylimidazolium bromides ([CCim]Br) with the same dodecyl long-chain tail (C) and the short alkyl side chain (C, n = 1-4), were synthesized, and their molecule structures were confirmed by ESI-MS, H-NMR and elemental analysis. The physicochemical properties of [CCim]Br ( n = 1-4) were determined by means of surface tension and fluorescence probe methods, respectively. It was found that elongation of the side chain length will bring about an enhancement of surface activity. Along with the side chain length increasing, the critical micelle concentration (CMC), surface tension at CMC ( γ), the maximum surface excess (Γ), micellar aggregation number ( N) and micellar microenvironment polarity of [CCim]Br decrease, while adsorption efficiency (p C), surface pressure at CMC (Π), the minimum molecular cross-sectional area ( A) at air-solution interfaces and CMC/ C ratio increase. [ABSTRACT FROM AUTHOR]

Zwitterionic imidazolium-based surfactants, namely 1-carboxymethyl-3-alkyl imidazolium inner salts (CimCM, n = 10, 12, and 14), were synthesized. Their molecule structures were characterized by means of electrospray ionization mass spectrometry (ESI-MS), H nuclear magnetic resonance (H NMR) and elemental analysis. Compared to the structurally related N-alkylbetaines (CHN(CH)CHCOO), the CMCs of CimCM are smaller than those of N-alkylbetaines. The effect of the long-chain length on the typical physicochemical properties of CimCM was studied. It is found that the lengthening of the long-chain enhances the surface activity of CimCM. The tendency for CimCM surfactants is similar to the case of the structurally related traditional zwitterionic N-alkylbetaines. [ABSTRACT FROM AUTHOR]

A novel zwitterionic imidazolium-based ionic liquid (IL) surfactant, 1-carboxymethyl-3-dodecylimidazolium inner salt, was synthesized. The molecule structure was confirmed by means of electrospray ionization mass spectrometry, H nuclear magnetic resonance and elemental analysis. The isoelectric point (pI) is 3.8 ± 0.1 at 35 ± 0.1 °C. The other important physicochemical parameters such as the critical micelle concentration (CMC), the surface tension at CMC (γ), the adsorption efficiency (p C), the surface pressure at CMC (Π), the maximum surface excess (Γ), the minimum molecular cross-sectional area ( A), the value of CMC/ C and the average number of aggregation ( N) were determined by surface tension and steady-state fluorescence probe methods, respectively. [ABSTRACT FROM AUTHOR]

This paper deals with the synthesis and self-aggregation of a hydroxyl-functionalized imidazolium-based ionic liquid (IL) surfactant, namely 1-hydroxyethyl-3-dodecylimidazolium chloride ([COHCim]Cl). The molecular structure was confirmed by means of electrospray ionization mass spectrometry (ESI-MS), H nuclear magnetic resonance (H NMR) and elemental analysis. Many important physicochemical parameters, such as the critical micelle concentration (CMC), the surface tension at CMC (γ), the adsorption efficiency (p C), the surface pressure at CMC (Π), the maximum surface excess (Γ), the minimum molecular cross-sectional area ( A), the value of CMC/ C, the average number of aggregation ( N) and the micellar microenvironment polarity were determined by surface tension-concentration curves, fluorescence spectra, and electrical conductivity. The phenomena of the second CMC, the concentration dependence of N, and the critical average aggregation number ( N) of imidazolium-based IL surfactants are reported for the first time in this paper. [ABSTRACT FROM AUTHOR]

Here, we present experimental surface tension isotherms of mixed solutions of a zwitterionic surfactant α-decylbetaine (DB) and an anionic surfactant sodium dodecyl sulfate (SDS) in different molar ratios. These mixed solutions show a composition dependency with respect to both surface tension effectiveness and critical micelle concentration. The pseudo-regular solution theory has been used to evaluate the interaction parameters in the micelle, β and at the surface, β. The results revealed that the mixed solutions of DB/SDS behave synergistically in both surface tension reduction effectiveness and mixed micelle formation at all mole fractions investigated. The values of adsorption area per surfactant molecule at air/solution interface were estimated, which provides some useful information on evaluating the interaction between DB and SDS in mixed adsorbed monolayers. The solubilization behaviors of toluene in DB/SDS mixed solutions were also investigated to help in understanding the structure of mixed micelles of DB and SDS. [ABSTRACT FROM AUTHOR]

A nucleophilic substitution reaction was developed to synthesize the zwitterionic surfactant using a renewable natural fatty acid rather than a petroleum derivative as the raw material. The kinetics and mechanism of the nucleophilic substitution reaction of trimethylamine α-chlorododecyl carboxylate with trimethylamine were investigated in protic and dipolar aprotic solvents including water, ethanol and N, N-dimethyl formamide. The rate equations were derived using initial rates and the activation parameters in different solvents were determined empirically and compared with each other to obtain important information about the reaction mechanism. The overall second-order reaction number and the negative activation entropy supported a bimolecular nucleophilic substitution (SN2) mechanism, combined with the pseudo-first-order kinetics for each reactant. The experimental results also showed that the reaction reactivity diminishes with the decrease in polarity of protic solvents. The typical dipolar aprotic solvent dimethyl formamide distinctively promoted the reaction in. This fact was successfully explained by the solvation rule for SN2 reactions. [ABSTRACT FROM AUTHOR]

An effective and economic two-step route was developed to synthesize the long alkyl chain betaine zwitterionic surfactant directly from natural fatty acids. The optimal processing conditions for synthesizing the intermediate and final product were probed and the yields of 96.4% and 88.3% were obtained for each step, respectively. The surface active behavior of the synthesized decylbetaine surfactant was investigated using the surface tension method. The related thermodynamic parameters were calculated and discussed. The fluorescence probe technology was applied to determine the micropolarity of decylbetaine micelles. [ABSTRACT FROM AUTHOR]

Sodium stearyl polyoxypropylene acetates (SC18PpC, p = 3, 6, 9) were synthesized through a two‐step process involving propoxylation of stearyl alcohol and subsequent carboxymethylation. Stearyl polyoxypropylene acetic acids (C18PpC, p = 3, 6, 9), the acidified products of SC18PpC, were characterized by FT‐IR, 1H‐NMR, and ESI‐MS. The properties of SC18PpC were extensively investigated and compared with sodium dodecanoate (SD) and sodium stearate (SS). The solubility of SC18PpC in cold water was enhanced. Kraft temperature (Tk) of SC18P3C is 40°C which is significantly lower than SS, and Tk of SC18PpC (p = 6, 9) are even less than 0°C. SC18PpC exhibits overall greater hard water resistance compared to SD and SS with the hardness of 0 to 450 mg/L. The hard water resistance of SC18PpC escalates proportionally with the length of the spacer, and the aqueous solution of SC18P9C retains its clarity even when exposed to the hard water of 450 mg/L, the maximum hardness level of Chinese tap water. SC18PpC demonstrates efficiency and effectiveness in reducing surface tension, as well as better foaming, emulsification and wetting power compared to SD and SS. These improved properties make SC18PpC (p = 3, 6) more effective in detergency on three typical soiled fabrics compared to that of sodium soap. Specifically, the detergency to sebum‐stained fabric of SC18P3C exhibits 1.5 times and 1.3 times improvement compared to SD and SS, respectively. Therefore, it is recommended to incorporate SC18PpC (p = 3, 6) in the detergent formulations for washing intimate apparel in tap water. [ABSTRACT FROM AUTHOR]