Micellization of Anionic Sulfonate Gemini Surfactants and Their Interactions With Anionic Polyacrylamide

Anionic sulfonate gemini surfactants 8‐s‐8(SO₃)₂ and 12‐s‐12(SO₃)₂ (s = 3, 6) were synthesized, and their micellization in aqueous solution at 25.0 °C and pH 9 was investigated. The results show that the critical micelle concentrations (CMC) of 8‐s‐8(SO₃)₂ are more than 2 orders of magnitude larger than those of 12‐s‐12(SO₃)₂, but the spacer length has a relatively small impact on the CMC. Moreover, the interactions of n‐s‐n(SO₃)₂ (n = 8, 12; s = 3, 6) with anionic polyacrylamide (PAM) at 25.0 °C and pH 9 were investigated using surface tensiometry, rheolgy, and scanning electron microscopy (SEM). The results indicate that the surface tension and rheological properties of PAM depend on the concentration of n‐s‐n(SO₃)₂. Below the critical aggregation concentration of C₁, surface tension is sharply reduced, the surface tension of n‐s‐n(SO₃)₂/PAM is lower than n‐s‐n(SO₃)₂ alone, but viscosity is almost unchanged with increasing C_{n‐s‐n(SO3)2}. Above C₁, surface tension reduces very slowly until the saturated concentration of C₂ is reached. Above C₂, surface tension rapidly reduces until C_M is attained, suggesting free n‐s‐n(SO₃)₂ micelles begin to form. In the region of C₁–C_M, the viscosity significantly increases. Above C_M, surface tension is basically unchanged and these curves coincide with those of the single surfactant system. Moreover, the viscosity is almost constant. The SEM images indicate that fibrous aggregates are formed below C₁, then transformed into multilayer fibrous aggregates above C₁, and further into fiber‐braided‐structured and spider‐web‐structured aggregates above C_M. The variation of viscosity is closely associated with the transformation of aggregates.     

一种不对称阴离子Gemini表面活性剂的合成及表面活性研究

以α-溴代十四酸乙酯和4-癸基苯酚为原料,经Williamson醚化、磺化及皂化反应制备了一种不对称阴离子Gemini表面活性剂α-(4-癸基-2-磺基)-苯氧基十四酸钠,简写为C12CO2Na-p-C10SO3Na,考察了醚化反应条件,并用FTIR和1HNMR表征了中间体及目标产物结构。结果表明,醚化反应的最佳条件为:以N,N-二甲基甲酰胺(DMF)和甲苯作溶剂,无水K2CO3作缚酸剂,物料比n(α-溴代十四酸乙酯)∶n(4-癸基苯酚)=1.05∶1,回流反应3 h,醚化产物收率为77.2%(以4-癸基苯酚计)。采用吊片法测定了目标产物的表面活性,其表面张力最低可降至26 mN/m左右,临界胶束浓度(CMC)为3.28×10-6mol/L,比相应常规单链表面活性剂十四烷酸钠和间癸基苯磺酸钠的CMC低3个数量级,体现出Gemini表面活性剂优异的表面活性。     

Synthesis,Micellization, and Surface Activity of Novel Linear-Dendritic Carboxylate Surfactants

Two generations of novel linear-dendritic carboxylate surfactants C₁₈-G₁-(COONa)₂ and C₁₈-G₂-(COONa)₄ have been synthesized by the divergent method and their structures are characterized by ¹H Nuclear Magnetic Resonance and Infrared analysis. The electrical conductivity measurement is used to measure the Krafft temperatures of C₁₈-G₁-(COONa)₂ and C₁₈-G₂-(COONa)₄, which are much smaller than those of the corresponding conventional surfactant sodium stearate. The markedly enhanced solubility of two linear-dendritic surfactants is ascribed to the high hydrophilicity of surfactant headgroups induced by the carboxylate and ester groups. The critical micelle concentration (CMC) values obtained from both the electrical conductivity and surface tension measurements indicate that the micellizations of linear-dendritic surfactants become favorable with the increase in the number of the surfactant headgroup. However, the surface activity parameters including the surface tension at the CMC, maximum surface excess, and minimum surface area reveal that C₁₈-G₁-(COONa)₂ exhibits greater efficiency in absorbing at the air/water interface compared to C₁₈-G₂-(COONa)₄, owing to their different steric repulsions of the surfactant headgroups. In addition, C₁₈-G₁-(COONa)₂ and C₁₈-G₂-(COONa)₄ have higher emulsifying ability than the conventional surfactants sodium stearate and sodium octadecyl sulfate.     

Synthesis and Surface Activities of Novel Succinic Acid Double-Tailed Sulfonate Fluorinated Surfactants

In this study, four environmentally friendly succinic acid double-tailed sulfonate fluorinated surfactants were synthesized from maleic anhydride, fluoroalkyl alcohols, namely 1-(1H,1H,7H-Dodecafluoroheptyloxy) ethanol, 1-(1H,1H,5H -octafluoropentyloxy) ethanol, 1-(1H,1H,3H-tetrafluoropropoxy) ethanol, and 1-(1H,1H -trifluoroethyoxy) ethanol, and sodium hydrogensulfite. The surfactant structure was characterized by FT-IR, ¹H NMR, and ¹⁹F NMR . Thermogravimetric results showed that the fluorinated surfactants were stable up to relatively high temperature. The Krafft points of the four novel succinic acid double-tailed sulfonate fluorinated surfactants were all below 0 °C. The lowest CMC value for the synthesized four double-tailed fluorine surfactants is about 0.076 mmol L^?1, far less than that of ammonium perfluorooctanoate (PFOA), demonstrating that double-tailed surfactants have higher surface activity than surfactants with one fluoroalkyl chain. The replacement of alkyl groups with oxyethylene groups enhances the hydrophilicity of the obtained fluorinated surfactants. Based on these findings, the synthesized surfactants may be environmentally friendly alternatives to PFOA and exhibit promising potential in industry applications.     

一种阴离子表面活性剂的合成与性能研究

合成了一种阴离子型双醚双苯磺酸盐Gemini表面活性剂,测定该系列Gemini表面活性剂水溶液的表面张力(γcmc)分别为:32.00mN/m、28.41 mN/m、29.76 mN/m、33.20 mN/m,临界胶束浓度(cmc)分别为:0.79mmol/L、0.87 mmol/L、1.02 mmol/L、0.84 mmol/L;该Gemini表面活性剂(DPDAS-12)可在无碱,浓度为0.35%条件下,将油/水界面张力降至1.2×10-3mN/m的超低水平;可有效改变岩石表面润湿性,可将亲油表面(θ=114°)改变为弱亲油(θ=69.3°),可将亲水表面(θ=26.0°)改变为弱亲水表面(θ=34.0°)。     

Surface Properties and Solubility Enhancement of Anionic/Nonionic Surfactant Mixtures Based on Sulfonate Gemini Surfactants

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.     

Properties of a Binary System Containing Anionic and Cationic Gemini Surfactants

Surface tension, fluorescence, and dynamic light scattering were used to investigate the properties of a binary surfactant system comprising an anionic gemini surfactant (DLMC) and cationic gemini surfactant (II‐12‐EO₂). Surface tension measurements afforded the critical micelle concentration (cmc) of the mixture and the values are all lower than those of pure constituent surfactants. For the mixtures of II‐12‐EO₂/DLMC, the micelle aggregation number decreases with the increase of II‐12‐EO₂, and the micropolarity of the micelle is lowest when the molar fraction of II‐12‐EO₂ is 0.5; the hydrodynamic radius (R_h) of the mixed micelle first increases and then decreases with the addition of II‐12‐EO₂, and larger micelles are obtained when the molar fraction of II‐12‐EO₂ is 0.5 or 0.7.     

阴离子磺酸盐双子表面活性剂的合成研究

以乙二胺,顺丁烯二酸酐、亚硫酸氢钠和十二醇为原料,通过三步法合成阴离子磺酸盐双子表面活性剂。通过正交实验考察了反应物投料比、反应温度和反应时间对目标产物收率的影响。研究表明合成目标产物的最优工艺条件为:中间体二乙胺双-(酰基丙酸-α-磺酸钠)b:十二醇摩尔比为1∶2.2,反应温度为145℃,反应时间为6h。产物结构经IR、1 H NMR表征为目标产物。     

氟化季铵盐表面活性剂的合成及其表面活性

以三氟乙酸乙酯和N,N-二甲基乙二胺为原料,经酰化反应制得中间体NDAET;然后将NDAET与溴代十二烷发生季铵化反应得到氟化季铵盐表面活性剂N,N-二甲基-N-{2-[(2,2,2-三氟乙酰基)氨基]乙基}-1-十二烷基铵溴化物(NDAET-12)。通过FTIR、13CNMR、1HNMR对其结构进行了表征。考察了反应物物质的量比、反应时间、反应温度、溶剂用量对NDAET-12产率的影响。在单因素实验的基础上,采用正交实验对NDAET-12的合成工艺进行了优化。NDAET-12的最佳合成工艺条件为:n(NDAET)∶n(溴代十二烷)=1.0∶1.3,NDAET质量为2.76g,反应时间12h,反应温度90℃,溶剂用量为20mL。在该条件下进行平行验证实验,得到NDAET-12的平均产率为86.75%。热重分析表明,NDAET-12是一种热稳定性较好的表面活性剂。对NDAET-12的临界胶束浓度(CMC)、表面活性和乳化性能进行了测定。NDAET-12的CMC为0.8 g/L,γCMC=25.15 mN/m,表面活性较好。与十二烷基三甲基溴化铵(DTAB)和十六烷基三甲基溴化铵(CTMAB)相比,NDAET-12从乳化体系中分出10mL所需要的时间最长,为473s,具有优异的乳化性能。     

Synthesis and Surface Properties of Anionic Gemini Surfactants having N-acylamide and Carboxylate Groups

A straightforward synthetic strategy to an anionic gemini surfactant having both N-acylamide and carboxylate groups in a molecule has been demonstrated. The surface properties of the anionic gemini surfactant, such as CMC (critical micelle concentration), C₂₀ (the concentration required to reduce the surface tension of the solvent by 20 mN/m), γ _CMC (the surface tension at the CMC), ∏ _CMC (the surface pressure at the CMC), Γ _max (the maximum surface excess concentration at the air/aqueous solution interface), A _min (the minimum area per surfactant molecule at the air/water interface), and the CMC/C₂₀ ratio (a measure of the tendency to form micelles relative to adsorbtion at the air/water interface), have been studied. The influence of the different concentrations of NaCl on the surface properties of the gemini surfactant has been discussed. The results have shown that the CMC values decreased with an increase in the concentration of NaCl indicating that the Na⁺ preferentially adsorbs onto the surface of the charged aggregate and facilitates the aggregate growth by suppressing the main impediment of electrostatic repulsion among head groups. Additionally, the values of Γ _max are always higher in salt solutions as compared to those in pure water due to their salting out effect. The larger pC₂₀ value indicates that the surfactant adsorbs more efficiently at the air/water interface and reduces surface tension more efficiently. In addition, the geminis in water show little or no break in their specific conductance versus surfactant molar concentration plots. This is attributable to protonation of the carboxylate group and strong Na⁺ release during micellization.     

Synthesis and Surface Activities of Novel Succinic Acid Monofluoroalkyl Sulfonate Surfactants

Two environmentally friendly succinic acid monofluoroalkyl sulfonate surfactants were synthesized from maleic anhydride and polyethylene glycol mono (1H,1H,7H‐dodecafluoroheptyl) ether, i.e. H(CF₂)₆CH₂OCH₂CH₂OCOCH(SO₃Na)CH₂COOH (FEOS‐1) and H(CF₂)₆CH₂(OCH₂CH₂)₃OCOCH(SO₃Na)CH₂COOH (FEOS‐3). The obtained surfactants were characterized by FT‐IR, ¹H NMR, ¹³C NMR and ¹⁹F NMR in detail. The synthesized fluorinated surfactants have a high thermal stability on the basis of thermogravimetric analysis. Their surface properties were examined and the results show that FEOS‐1 and FEOS‐3 surfactants can reduce the surface tension of water to 25.55 mN m^?1 at 10.25 mmol L^?1 and 21.63 mN m^?1 at 8.33 mmol L^?1, respectively; meanwhile, the introduction of oxyethylene groups enhances the hydrophilicity and micellar forming ability and the longer oxyethylene chains the better surface properties. The Krafft points (K_p) of FEOS‐1 and FEOS‐3 were both below 0 °C, which was lower than perfluoro‐n‐heptanesulfonic acid sodium salt (n‐C₇F₁₅SO₃Na, K_p = 56.5 °C) at a similar length of fluorocarbon chains. Comparison studies on two surfactants above and the conventional fluorocarbon surfactants, perfluorooctanoate of ammonium (PFOA) show that the surfactants have comparable properties to PFOA, thus offering an environmentally friendly synthesizing alternatives to PFOA.     

A New Anionic Oxalamide Lauryl Succinate Sodium Sulfonate Gemini Surfactant: Microwave-Assisted Synthesis and Surface Activities

An anionic Gemini surfactant, oxalamide lauryl succinate sodium sulfonate, was synthesized successfully through amidation, esterification and sulfonation reactions under microwave irradiation conditions by using maleic anhydride, ethylenediamine, lauryl alcohol, sodium sulfite as the starting materials. The best reaction conditions for synthesize the target product were obtained by single factor and orthogonal optimization methods. FTIR, elemental analysis and ¹H‐NMR analysis were used to confirm the chemical structure of the surfactant. The critical micelle concentration (CMC) in aqueous solution, surface tension, emulsification capacity and foaming power were determined. The critical micelle concentration and γ_CMC are respectively equal to 3.5 × 10^?4 mol L^?1 and 21.5 mN m^?1. It was found that microwave‐assisted synthesis is an efficient means of preparation of this anionic Gemini surfactant with shorter times and higher yields.     

Synthesis and Surface Activity of Cationic Amino Acid-Based Surfactants in Aqueous Solution

I studied the possibility of using amino acid-based surfactants as emulsifiers at the same time as preservatives. Fourteen lipopeptides were synthesized employing a solid phase peptide synthesis procedure. All compounds were designed to be positively charged from +1 to +4 and acylated with fatty acid chain—palmitic and miristic. The surface activity of the obtained lipopeptides was tested using a semi-automatic tensiometer to calculate parameters describing the behavior of lipopeptides in the air/water interface. Such parameters as CMC, surface tension at the CMC point (σ _CMC), effectiveness (π _CMC), and efficiency (pC20) were measured. Emulsifying properties of all lipopeptides were also examined. The studies reveal that the surface active properties of synthesized compounds strongly depend on the length of alkyl chains as well as on the composition of amino acid polar heads. The critical micelle concentration decreases with increasing alkyl chain length of lipopeptides with the same polar head. The effectiveness and efficiency decrease when the number of amino acids in the polar head increases. All lipopeptides established a very weak emulsification power and created unstable water/Miglyol 812 and water/paraffin oil emulsions. Results suggest that lipopeptides cannot be used as emulsifiers; nonetheless, it is possible to use them as auxiliary surfactants with disinfectant properties in combination with more potent emulsifiers.     

季铵盐双子表面活性剂的合成和表面活性

以吗啉和溴代烷为原料,合成了两种季铵盐双子表面活性剂(m-6-m,m=10,12),并用IR和1HNMR表征了其结构。测得28℃时,12-6-12和10-6-10的表面张力(γCMC)分别为26.45 mN/m和25.55 mN/m;临界胶束浓度(CMC)分别为1.0 mmol/L和3.1 mmol/L;pC20值分别为3.48和3.03;比表面过剩(Γmax)分别为2.72×10-6mol/m2和2.80×10-6mol/m2;分子最小截面积(Amin)分别为0.611 nm2和0.593 nm2。结果表明,该季铵盐双子表面活性剂与相同离子头基及烷基链的单季铵盐表面活性剂相比,CMC低一个数量级,γCMC相差不大。     

Synthesis,Surface and Antimicrobial Activities of Novel Cationic Gemini Surfactants

A series of novel cationic gemini surfactants [C_nH_2n+1–O–CH₂–CH(OH)–CH₂–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? [ 3a (n = 12), 3b (n = 14) and 3c (n = 16)] having a 2‐hydroxy‐1,3‐oxypropylene group [?CH₂–CH(OH)–CH₂–O–] in the hydrophobic chain have been synthesized and characterized. Their water solubility, surface activity, foaming properties, and antibacterial activity have been examined. The critical micelle concentration (CMC) values of the novel cationic gemini surfactants are one to two orders of magnitude smaller than those of the corresponding monomeric surfactants. Furthermore, the novel cationic gemini surfactants have better water solubility and surface activity than the comparable [C_nH_2n+1–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? (n‐4‐n) geminis. The novel cationic gemini surfactants 3a and 3b also exhibit good foaming properties and show good antibacterial and antifungal activities.     

Surface Activity,Aggregation, and Wetting Behavior of Sodium P-Perfluorononenyloxy Benzene Sulfonate

The physicochemical properties of sodium p-perfluorononenyloxy benzene sulfonate (OBS) in aqueous solution were investigated. Compared to linear alkylbenzene sulfonate (LAS), OBS has a lower critical micelle concentration (CMC) and a low surface tension at the CMC. At the same concentration, OBS shows lower dynamic surface tension than LAS indicating faster wetting kinetics. In aqueous solution, OBS forms large spherical vesicles above the CMC. OBS shows excellent dynamic wetting properties on low-energy surfaces. The superior properties of OBS make it ideal for use in many industry fields.     

Synthesis, Surface and Thermodynamic Properties of Substituted Polytriethanolamine Nonionic Surfactants

Three series of nonionic surfactants derived from polytriethanolamine containing 8, 10, and 12 units of triethanolamine were synthesized. Structural assignment of the different compounds was made on the basis of FTIR and ¹H‐NMR spectroscopic data. The surface parameters of these surfactants included critical micelle concentration (CMC), surface tension at the CMC (γ_CMC), surfactant concentration required to reduce the surface tension of the solvent by 20 mN m^?1 (pC₂₀), maximum surface excess (Γ_max), and the interfacial area occupied by the surfactant molecules (A_min) using surface tension measurements. The micellization and adsorption free energies were calculated at 25 °C.     

Synthesis and Performance of a Multi-Purpose Gemini Precursor and the Derivative Alkylaryl Sulfonate Gemini Surfactants

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.     

Synthesis,Surface Activity,Thermodynamic Parameters,and Performance Evaluation of Branched Carboxylate Gemini Surfactants

Three novel carboxylate gemini surfactants (3C_ntaDA, n = 8, 10, and 12) were synthesized by two simple steps, and their structures were characterized using FT-IR and ¹H NMR. The surface activities of these surfactants were obtained from surface tension measurements at different temperatures, and the surface parameters containing the critical micelle concentration (CMC), surface tension (γ), minimum surface area per molecule ( A_min ), and maximum surface excess concentration ( Γ_max ) were obtained from surface tension measurements. The experimental results show that 3C_ntaDA surfactants have higher surface activities compared with the corresponding conventional surfactants. The thermodynamic parameters of the micellization process were investigated, and the calculated results show that it was an exothermic and spontaneous process. The emulsification and foam performance of these surfactants were also evaluated at different concentrations at 298.15 K.     

Synthesis and Surface Properties of Novel Gemini Imidazolium Surfactants

Five new Gemini imidazolium surfactants were synthesized from imidazole and 1-bromoalkane (C₈, C₁₀, C₁₂, C₁₄, C₁₆) to get 1-alkylimidazole, which was further reacted with 1,3-dichloropropan-2-ol to form the surfactant molecule, 1,1′-(propane-1,3-diyl-2-ol) bis(3-alkyl-1H-imidazol-3-ium) chloride. The structures of the five new surfactants and intermediates were characterized by ¹H-NMR, ¹³C-NMR and IR spectra. Thermal properties of the five new surfactants were studied with thermogravimetric analysis and differential scanning calorimetry, the five new surfactants showed a transition from a crystalline phase to a thermotropic liquid–crystalline phase at around ca. 100 °C, which transformed to an isotropic liquid phase at around ca. 165 °C. The five new surfactants critical micelle concentrations (CMC) in the aqueous solutions were determined by surface tension and electrical conductivity methods. The surface tension measurements provided a series of parameters, including critical micelle concentration (CMC), surface tension at the CMC (γ _CMC), adsorption efficiency  (pC ₂₀), and effectiveness of surface tension reduction (π_CMC). In addition, with application of the Gibbs adsorption isotherm, maximum surface excess concentration (Γ_max) and minimum surface area/molecule (A_min) at the air–water interface were obtained. The parameters β (degree of counterion binding to micelles), ΔG _ads ^θ (Gibbs free energy of adsorption), and ΔG _mic ^θ (Gibbs free energy change of micellization) were also derived. The results indicated that the five new Gemini surfactants exhibited very low CMC and a good efficiency in lowering the surface tension of water. The foamability and foam stability of the five new surfactants were also examined at different CMC.