On the measurement of critical micelle concentrations of pure and technical-grade nonionic surfactants

The critical micelle concentrations (CMC) of nine commercial nonionic surfactants (Tween 20, 22, 40, 60, and 80; Triton X-100; Brij 35, 58, and 78) and two pure nonionics [C₁₂(EO)₅ and C₁₂(EO)₈] were determined by surface tension and dye micellization methods. Commercially available nonionic surfactants (technical grade) usually contain impurities and have a broad molecular weight distribution owing to the degree of ethoxylation. It was shown that the surface tension method (Wilhelmy plate) is very sensitive to the presence of impurities. Much lower CMC values were obtained with the surface tension method than with the dye micellization method (up to 6.5 times for Tween 22). In the presence of highly surfaceactive impurities, the air/liquid interface is already saturated at concentrations well below the true CMC, leading to a wrong interpretation of the break in the curve of surface tension (γ) vs. concentration of nonionic surfactant (log C). The actual onset of micellization happens at higher concentrations, as measured by the dye micellization method. Furthermore, it was shown that when a commercial surfactant sample (Tween 20) is subjected to foam fractionation, thereby removing species with higher surface activity, the sample yields almost the same CMC values as measured by surface tension and dye micellization methods. It was found that for monodisperse pure nonionic surfactants, both CMC determination methods yield the same results. Therefore, this study indicates that precaution should be taken when determining the CMC of commercial nonionic surfactants by the surface tension method, as it indicates the surface concentration of all surface-active species at the surface only, whereas the dye method indicates the presence of micelles in the bulk solution.     

唑型双子表面活性剂的合成和性能研究

以咪唑、以咪唑,溴乙酸,溴代十四烷和二元醇为主要原料,采用三步法合成了三种新的咪唑型双子表面活性剂,简记[C_(14)-n-C_(14)]Br_2。通过核磁氢谱和红外光谱对三种产物的结构进行表征,证明合成的产物为目标产物。并采用表面张力法得出三种表面活性剂的表面张力曲线,进而计算临界胶束浓度(CMC)等一系列表面性能参数,结果表明,连接基越短的咪唑型双子表面活性剂拥有更低的CMC,更高的界面活性。     

双烷基双硫酸酯钠表面活性剂的合成

以1,2-环氧十四烷烃和几种短碳链二醇为原料,合成了系列二烷基二羟基化合物,然后用氯磺酸作为磺化剂制得5种疏水链相同、连接基团不同的双烷基双硫酸酯钠表面活性剂,并用核磁共振氢谱(1HNMR)、傅立叶变换红外光谱(FTIR)和电喷雾质谱(ESI-MS)对其结构进行了鉴定。用Wilhelmy-Plate法测定了25℃时,5种表面活性剂水溶液的表面张力。实验发现,双直链烷基双硫酸酯钠有很低的临界胶束浓度约10-5mol/L,表明该类表面活性剂具有较好的表面活性。     

长链烷基苯磺酸钠Gemini表面活性剂的合成和表面活性

以脂肪酸、苯酚、乙二醇为原料,经酰化反应、酯化反应、Fries重排、氢化还原反应、磺化以及中和反应等步骤,合成出3种长链烷基苯磺酸钠Gem in i表面活性剂。用IR、1HNMR和ESI-MS对产物进行了结构鉴定。以W ilhelmy-p late法测定了30℃时它们在水溶液中的临界胶束浓度(CMC)和临界胶束浓度下的表面张力(γCMC)。纯水溶液中其临界胶束浓度(CMC)为10-4~10-5mol/L,γCMC为35~37 mN/m;随着苯环上长链烷基碳数(n=8、10、12)的增加,CMC分别为5.94×10-4、1.53×10-5、0.46×10-5mol/L;γCMC分别为36.9、34.4、34.4 mN/m。结果表明,此类表面活性剂具有比较好的表面活性。     

Synthesis and Antibacterial Activity of Novel Amido-Amine-Based Cationic Gemini Surfactants

A series of novel cationic gemini surfactants were synthesized from corresponding amido-amines in a single step reaction. The amido-amines were obtained from long chain carboxylic acids and 3-N,N-dimethylamino-1-propyl-amine with excellent isolated yield (up to 95 %). All the synthesized quaternary ammonium compounds (QACs) were further investigated for surface active properties. The critical micelle concentration (CMC) and the effectiveness of surface tension reduction were determined. The surface tension measurements of newly synthesized gemini surfactants showed good water solubility, and low CMC values, had great efficiency in lowering the surface tension and a strong adsorption at the air/water interface than the corresponding monomeric surfactants. Further, the antibacterial activity of the synthesized QACs against both Gram-positive and Gram-negative bacteria was also investigated.     

对-烷基-苄基聚氧乙烯醚羧酸甜菜碱的合成与表面活性

以脂肪酸、苯、二缩三乙二醇为原料,经酰化反应、黄鸣龙还原反应、氯甲基化反应、威廉逊成醚反应、卤化反应、季铵化反应,合成出了3个对烷基苄基聚氧乙烯醚羧酸甜菜碱两性离子表面活性剂。用IR、1HNMR和ESI-MS对产物进行了结构鉴定。用Wilhelmy-plate法测定了30℃时它们在水溶液中的临界胶束浓度(CMC)和临界胶束浓度下的表面张力(γCMC)。实验表明,纯水溶液中表面活性剂的临界胶束浓度(CMC)为10-4～10-6mol/L,临界胶束浓度下的表面张力(γCMC)为27～30 mN/m;随着苯环上长链烷基碳数(n=8、10、12)的增加,CMC分别为1.12×10-4、1.51×10-5、6.21×10-6 mol/L;γCMC分别为27.9、28.4、29.9 mN/m。结果表明,该类表面活性剂具有比较好的表面活性。     

Simple and Efficient Synthesis and Surfactant Properties of <Emphasis Type="Italic">N</Emphasis>-Alkyl-3-Boronopyridinium Acid Triflates

In this paper, we describe a simple and efficient procedure of original N-alkyl-3-boronopyridinium triflates synthesis and report on the surface properties of these surfactants. Key micellar parameters were obtained, the critical micelle concentrations (CMC values) were determined and compared to conventional ionic surfactants as well as the surface activity of these surfactants (pC ₂₀ value and the surface tension at the CMC). These new boronic functionalized surfactants exhibit a stunning efficiency in their tendency to self-assemble and are significantly more surface active that their conventional analogues. This new family of surfactants represents a new direction in both functionality and performance, and may open perspectives in chemical synthesis and applications.     

Surface tension study of the interaction between two nonionic surfactants and two direct dyes

The complex-forming interaction between two direct dyes, CI Yellow 106 and CI Blue 78, and two nonionic surfactants, namely, polyoxyethylene nonyl phenyl ether (NP-12) and polyoxyethylene stearylamine (R-11), in aqueous solutions was studied. The estimation was made by measuring surface tension and critical micelle concentration (CMC) changes as a function of dye concentration. A decrease of NP-12 surface tension at low concentration and an increase of R-11 surface tension in the presence of both dyes were observed along with a significant decrease of NP-12 CMC values. A difference in the spectrophotometric absorbance of dye solutions in the presence of both surfactants, indicating a change in the environment of the dye chromophore, was also visible. These results confirm the formation of hydrophobic complexes of NP-12 and hydrophilic complexes of R-11 with both dyes.     

Influence of Spacer Nature on the Aggregation Properties of Anionic Gemini Surfactants in Aqueous Solutions

A series of anionic gemini surfactants with the same structure except the spacer nature have been studied. Their solution properties were characterized by the equilibrium surface tension and intrinsic fluorescence quenching method. The critical micelle concentrations (CMC), surface tension at cmc, C₂₀, and the micelle aggregation number (N) were obtained. The surface tension measurements indicate that these gemini surfactants have much lower cmc values and great efficiency in lowering the surface tension of water compared with those of conventional monomeric surfactants. Furthermore, the standard free energy of micellization for anionic gemini surfactants was also determined. The results showed that the nature of the spacer has an important effect on the aggregation properties of gemini surfactants in aqueous solutions. The surfactant with a hydrophilic, flexible spacer was more readily able to form micelle compared with the surfactant with a hydrophobic, rigid spacer, which leads to a lower CMC value, larger N, more negative free energy of micellization, and a more closely packed micelle structure.     

温度及无机盐对LMEE和SDS混合溶液表面张力的影响

通过表面张力的测定,研究了温度和不同无机盐对月桂酸甲酯乙氧基化物(laurylmethylesterethoxylate,简称LMEE)与十二烷基硫酸钠(SDS)复配物表面张力及临界胶束浓度(CMC)的影响。研究表明:混合体系的CMC在很宽的复配比例内出现最低值,25℃、未加无机盐时可使CMC最低降至3 8×10-5mol/L;温度对复配体系表面张力的影响较小,温度上升复配物的CMC略有降低。3种价态无机盐的加入均可使复配物的CMC有所降低,但与单一表面活性剂相比,温度和无机盐对复配物的CMC影响均不大,说明复配体系的抗温变及抗盐能力均有增强。     

Surface Activity of Monomeric and Polymeric (3-alkyloxy aniline) Surfactants

ABSTRACT

The adsorption and micellization processes of 3-alkyloxy aniline namely [3-decyloxy aniline (C10M), 3-dodecyloxy aniline (C12M) and 3-cetyloxy aniline (C16M)] and their polymers [C10P, C12P and C16P] have been investigated using surface tension (γ) measurements at different temperatures. The synthesized monomers and polymers have been characterized by IR and elemental analysis. The surface and thermodynamic parameters of these monomeric and polymeric surfactants are investigated. The results show that the critical micelle concentration (CMC) of the polymeric surfactants is lower than that of monomers. The CMC values decreases as the hydrophobic chain lengthens for both monomeric and polymeric surfactants. The surface parameters show the ability of monomeric and polymeric surfactants to adsorb at the air/water interface and decrease the surface tension. The thermodynamic parameters reveal that the micellization process is spontaneous for all investigated surfactants. The specific conductance measurements show that the specific conductance increases with increasing chain length of the substituted alkyl groups, the synthesized polymeric surfactants have higher values of specific conductance than the corresponding monomers and the specific conductance increases with rising solution temperature.     

Equilibrium and Dynamic Surface Properties of Sulfosuccinate Surfactants

The equilibrium and dynamic surface tension of three sulfosuccinate surfactants at the air/aqueous solution interface were investigated. Wilhelmy plate method was used to determine critical micelle concentration (CMC) and the equilibrium surface tension (γ _eq). The dynamic surface tensions in the range 10–100 s were measured by maximum bubble pressure method. The well-known Ward–Tordai equation was employed to analyze the adsorption of the sulfosuccinate surfactants. The parameters and effective diffusion coefficients (D _eff) of dynamic surface tension have been calculated and analyzed. The equilibrium surface tension results showed that disodium laureth (3) sulfosuccinate (AEO₃-SS), disodium laureth (6) sulfosuccinate (AEO₆-SS) and disodium alkyl ethoxy glucoside sulfosuccinate (AEG-SS) are surfactants possessing strong surface activity, adsorbing to the interface rapidly and their γ _eq values were in the range 25–32 mN/m. CMC of the three surfactants increases with the number of hydrophilic groups and AEO₃-SS has the lowest CMC. According to the values of some dynamic surface tension parameters, AEG-SS is the most hydrophilic surfactant of them and AEO₃-SS is energetically more favorable to adsorb to the interface than the others. According to Ward–Tordai equation, the D _eff values were calculated, the adsorption mechanism was diffusion controlled at short times and toward the end good evidence was found for an activated-diffusion mechanism with an energy barrier.     

Guerbet十四醇聚氧乙烯醚硫酸钠的合成与表面活性

以Guerbet十四醇 (C14 GA)为中间体 ,经Williamson反应合成Guerbet十四醇聚氧乙烯醚醇〔C14 GA(EO) nH ,n =1,2 ,4〕 ,再经氯磺酸酯化及NaOH中和 ,得到阴离子表面活性剂Guerbet十四醇聚氧乙烯醚硫酸钠〔C14 GA(EO) nS ,n =1,2 ,4〕。用IR、NMR和元素分析测定了所合成的表面活性剂的结构 ,并利用表面张力法测定了这些表面活性剂水溶液的表面活性。实验结果表明 :所合成的表面活性剂的结构分别为C14 GAEOS (A) ,C14 GA(EO) 2 S(B)和C14 GA(EO) 4 S(C) ;这些表面活性剂其临界胶束浓度CMC(mmol/L) ,在CMC时的表面张力γCMC(mN/m)和Krafft点 (℃ )分别为A :2 5 8mmol/L ,2 7 6mN/m ,5 9℃ ;B :0 80mmol/L ,2 6 4mN/m ,2℃和C :0 12mmol/L ,2 5 3mN/m ,0℃。均比常用的直链阴离子表面活性剂C12 H2 5SO4Na(8.6mmol/L ,4 1 2mN/m ,16℃ )有更低的CMC ,γCMC和Krafft点 ;聚氧乙烯基的引入 ,对降低CMC ,γCMC和Krafft点的效果随氧乙烯基团数目的增多 (由 1增至 4 )而加大。讨论了表面活性剂的结构和表面活性的关系     

Polymeric surfactants for enhanced oil recovery. Part I—critical micelle concentration of some ethoxylated alkylphenol—formaldehyde nonionics

Four low molecular weight nonionic polymeric surfactants were prepared by condensing octyl-, dodecyl-, tetradecyl- and hexadecylphenol with para-formaldehyde, and then reacting the resulting resins with ethylene oxide to obtain products with the desired degree of ethoxylation. The molecular weights of the prepared alkylphenol-formaldehyde resins (prior to ethoxylation) were determined by vapour pressure osmometry. The surface tensions of aqueous solutions of these nonionic polymeric surfactants were determined by using the spinning drop method. Plotting the surface tensions obtained versus the logarithm of concentrations resulted in two lines: the pre-CMC (CMC = critical micelle concentration) line (the linear portion below the CMC value) and the post-CMC line (the linear portion above the CMC value). Least squares regression analysis was performed to get the best equation for each of the two lines. Solving these two equations simultaneously resulted in the value of the CMC and the corresponding surface tension (γ_CMC) for each surfactant of the four polymeric nonionic groups. The CMC values obtained for these polymeric surfactants are of the same order of magnitude obtained for monomeric and other polymeric nonionic surfactants.     

Synthesis and Properties of Dissymmetric Gemini Surfactants

A series of novel dissymmetric gemini cationics surfactants was synthesized by three-step reactions. The dissymmetric gemini surfactants contain a dodecanoic acid dimethylethylamine ester as the constant cationic part on one side of the hydroxypropyl center and a similar other cationic part, but with a different acid length (from octanoic to palmitic), on the other side. The critical micelle concentration (CMC) and the effectiveness of surface tension reduction (γ _CMC) were determined. The surface tension measurements of dissymmetric gemini surfactants showed good water solubility, and low CMC had great efficiency in lowering the surface tension and a strong adsorption at the air/water interface. The CMC was observed to increase initially with the increase of the ester bond alkyl group. They also showed good foaming properties and wetting capabilites.     

Micelle formation of polyoxyethylene-polyoxypropylene surfactants

Contradictory literature references on their micelle formation led to an investigation of block copolymers of ethylene and propylene oxides. By means of differential absorbance measurements of the dye-surfactant complex, critical micelle concentrations (CMC’s) for these polyols were determined. CMC values for surfactants with a molecular weight range of 1,100 to over 15,000 varied from 3.0 to 11.1 μmoles per liter, which are much lower than for other nonionics normally encountered. Corroborative data were obtained by the surface tension depression method. An increase in temperature below the cloud point or the addition of sodium chloride resulted in an increase in the CMC, which is not usual for many nonionics. Presented at the AOCS meeting, Houston, April, 1965.     

Synthesis and Study of the Surface Properties of Alkylnaphthalene and Alkylphenanthrene Sulfonates

Some alkylnaphthalene and alkylphenanthrene sulfonates were synthesized by means of a Wurtz–Fittig reaction. The HLB values for the prepared compounds were calculated, and the basic properties were studied in water at different temperatures, namely, 25, 35 and 45 °C. Through surface tension measurements, the following values were determined: the critical micelle concentration (CMC) and the surface tension at the CMC (γ_CMC). The following values were calculated: area per molecule at the CMC (A_CMC), standard free energy change of micellization (ΔG _mic), standard free energy of adsorption (ΔG _ad), and the efficiency of a surfactant in reducing surface tension (pC20). Furthermore, the partition coefficients of the synthesized compounds were also measured. The results show that n-alkylnaphthalene and n-alkylphenanthrene surfactants studied exhibit desirable properties that may be of value in some fields such as detergency. To confirm the detergency power of the prepared surfactants, some foam studies were performed.     

表面活性剂的复配及对甲维盐微乳剂物理稳定性的影响

通过测定不同类型的单一及复配型表面活性剂水溶液的临界胶束浓度和表面张力,研究了它对w(甲维盐)=1％的微乳剂物理稳定性的影响。膦酸酯类阴离子表面活性剂A的临界胶束浓度为1．79×10-4 mol／L,表面张力为28．90 mN/m;苄基酚聚氧乙烯聚氧丙烯醚嵌段型非离子表面活性剂B(EPE型)的临界胶束浓度为 1.91×10-4 mol/L,表面张力为20．70 mN/m;按m(A):m(B)=2:3形成的复配型表面活性剂2#的水溶液的临界胶束浓度为9．30×10-5 moL/L,表面张力为25．66 mN/m。当w(2#)=10％时,配制w(甲维盐)=1％的微乳剂物理稳定性最佳,各项指标均合格。     

Surface Activities, Foam Properties, HLB, and Krafft Point of Some n-Alkanesulfonates (C14–C18) with Different Isomeric Distributions

A homologue series of sodium secondary n-alkanesulfonates (C₁₄, C₁₆ and C₁₈) were obtained by photosulfochlorination process with two different reaction conditions. Different length chains with different isomeric distributions of n-alkanesulfonates are expected to present variations in physicochemical properties. In this investigation, the relationships between their isomeric distribution and their chain length and micellar behaviors were thoroughly explored. Their CMC at different temperatures were determined using specific conductivity and surface tension measurements. Through surface tension isotherms, the surface activities (??_CMC) were obtained. The surface absorption amounts (??_max) and the molecular areas (A _min) were calculated using Gibb??s equation. As expected, these surfactants exhibit good surface properties. It was shown that the CMC values increase with increasing the percentage of secondary isomers, with a surface tension decrease. It was also shown that the CMC values decrease with increasing chain length. The HLB values were calculated for each surfactant and the results obtained suggest that they are O/W emulsifiers. The foam properties of synthesized surfactants were evaluated and compared to those obtained for commercial samples. It was shown that the foamability is influenced both by the length of the hydrophobic moiety and the percentage of secondary isomers. It can be easily concluded that the C₁₄ sulfonates show the best foaming properties independently of their isomeric distribution. The Krafft point values obtained indicate that the micellization and the surfactant solubility mainly depend on the proportion of secondary isomers and the length of hydrophobic moiety.     

2-羟基-3-辛基-5-长链烷基苯磺酸钠的合成及表面活性

以脂肪酸、苯酚为原料,经酰化反应、酯化反应、Fries重排、氢化还原反应、磺化以及中和反应等步骤,合成出了2-羟基-3-辛基-5-长链烷基苯磺酸钠表面活性剂。两相滴定法测定了产物的质量分数均大于99%;用核磁共振氢谱、傅立叶红外光谱和质谱对产物进行了结构鉴定。用悬挂滴法测定了30℃时该系列表面活性剂的表面张力。实验发现,纯水溶液中表面活性剂的临界胶束浓度(CMC)达到10-6mol/L数量级,临界胶束浓度下的表面张力(γCMC)均小于28 mN/m;随着苯环上长链烷基碳数(n=8,10,12)的增加,CMC降低,分别为1.06×10-5,3.35×10-6,2.65×10-6mol/L;而γCMC变化不明显,分别为26.77,26.89,27.22 mN/m。结果表明,此类表面活性剂具有比较好的表面活性。