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.     

松香聚乙二醇柠檬酸酯表面活性剂的合成及性能研究

以松香为主要原料 ,与聚乙二醇、柠檬酸反应 ,合成一种新型表面活性剂。探讨了该表面活性剂的表面张力 (νc Mc) ,临界胶束浓度 ( Cc Mc) ,泡沫性 ,乳化性 ,润湿性等。结果为 :νc Mc35 .2× 1 0 -3 N/m;Cc Mc0 .5 62 3mol/L,HLB值 1 1 .6,泡沫力 (高度 1 73mm) ,乳化力 ( v H2 O5 5 .8m L) ,润湿性 1 0 5 s,结果表明是一种性能优良的非离子表面活性剂     

Structural and Physicochemical Properties of a Polymerizable Surfactant Synthesized from <Emphasis Type="Italic">N</Emphasis>-Methylol Acrylamide

A new polymerizable nonionic surfactant with reactive vinyl groups has been synthesized from N‐methylol acrylamide using a two‐step procedure. The structure of the surfactant molecule was characterized by Fourier transform infrared, ¹H nuclear magnetic resonance and mass spectroscopy. The surface active properties alongside its self‐assembly properties were investigated by surface tension, electrical conductivity, and fluorescence spectroscopy measurements. As compared with other nonionic surfactants, this study showed that this polymerizable surfactant possesses slightly a higher critical micelle concentration (CMC) value and the surface tension value at CMC. The obtained CMC values were compatible among measurements, ca. 0.02–0.038 M. The evidence of micelle formation also provided by the zeta potential measurements and the obtained zeta potential values showed that the polymerizable surfactant solutions had limited stability. The hydrolysis stability and solubility of the polymerizable surfactant were also investigated. The solubility results have shown that it was soluble in polar solvents while insoluble in nonpolar solvents both at room temperature and 40 °C. The acidic and basic hydrolysis of the surfactant increased as the temperature increased and the hydrolysis stability was 180 min (basic medium) and 55 min (acidic medium) at 80 °C.     

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。     

Aggregation and Phase Separation Phenomenon of Amitriptyline Hydrochloride Under the Influence of Pharmaceutical Excipients

The interaction between the amphiphilic drug amitriptyline hydrochloride (AMT) and the nonionic surfactants used in drug delivery has been investigated. Herein, we report the micellization behavior of AMT in presence of ethoxylated alkyl phenols in aqueous medium and the clouding phenomenon in the absence and presence of different nonionic surfactants in buffer solution. The values of critical micelle concentration (CMC) of AMT obtained using the conductivity method, decrease as nonionic surfactant concentration increases. With an increase in temperature, the CMC first increases and then decreases. At 303.15 K, the maximum CMC values were obtained with or without nonionic surfactant. The results obtained indicate attractive interactions (synergism) between the two mixing amphiphiles in solution. The experimentally obtained critical micelle concentration (CMC) values are always lower than ideal CMC values. Micellar mole fraction (X₁) values, calculated by different proposed models, show the contribution of nonionic surfactant concentration. At a fixed drug concentration (50 mmol kg^?1) and pH (=6.7) nonionic surfactants show continuous increase in cloud point (CP). Increase in drug concentration and pH, in the presence of fixed amounts of nonionic surfactant, increases and decreases the CP, respectively.     

以酯基为连接基的非离子双子表面活性剂的合成

以蓖麻油酸（RA）、聚乙二醇（600）为原料,马来酸酐为连接基,合成了一种新型的非离子双子表面活性剂MARAPEG-15,考察了催化剂用量、物料摩尔配比、反应时间及温度对酸酐与蓖麻油酸聚乙二醇硼酸酯酯化的影响,并测定了产物的临界胶束浓度和表面张力。马来酸酐与蓖麻油酸聚乙二醇硼酸酯酯化较佳的工艺条件为：催化剂用量为总质量的3%,n（酸酐）∶n（蓖麻油酸聚乙二醇硼酸酯）为3.1∶2,反应温度为110℃,时间为4 h;硼酸酯键水解时间为1.5 h。产物的表面张力及其临界胶束浓度为γCMC=35.73 mN/m,CMC=1.96×10-5mol/L。     

Alcohols Effect on Critic Micelle Concentration of Polysorbate 20 and Cetyl Trimethyl Ammonium Bromine Mixed Solutions

In this research, the micellar behavior of a cationic surfactant, cetyl trimethyl ammonium bromide (CTAB) and an nonionic surfactant, polysorbate 20 (Polyoxyethylene (20) sorbitan monolaurate) in different alcohol solutions media was investigated over the temperature range 293.15–313.15 K. The interaction between two surfactants in binary systems can be determined by calculating the values of their β parameters. The critical micelle concentrations (CMC) of the micelles were determined from the surface tension, the conductivity at different temperatures. The CMC behavior of CTAB and polysorbate 20 was analyzed in terms of the effect of temperature and the increase in the alcohol carbon chain. Changes in the critical micelle concentration of mixed surfactant systems of different alcohol solutions were measured. The CMC decreased sharply as the hydrocarbon chain length of the alcohols becomes larger. This shows that the more hydrophobic alcohols are, the more marked a decrease in CMC is observed.     

Comparative Study of Effect of Surfactant-Polymer Interactions on Properties of Alkyl Polyglucosides and Alpha Olefin Sulphonate

The properties of Alpha Olefin Sulphonate (AOS) and Alkyl polyglucosides (APG) were studied in the presence and absence of nonionic polymers such as polyethylene glycol, poly vinyl pyrrolidone and methyl cellulose and hydroxy propyl cellulose. Properties like surface tension, foaming, viscosity and emulsification were studied at a constant concentration of polymer (0.1%) and varying concentrations of surfactant. It was found that at low surfactant concentrations there is an association between surfactant and polymer at the liquid/air surface in the case of an anionic surfactant and a nonionic polymer, which is not seen in the case of nonionic surfactants and nonionic polymers. A nonionic polymer reduces the surface tension of AOS by forming a surfactant-polymer complex which in turn increases the foamability, emulsifying property and viscosity of solution. APG does not show any effect on its surface tension in the presence of nonionic polymers but its foamability and emulsifying properties are improved. Reduction in surface tension is not the only reason behind increased foamability in the presence of the polymer. Higher molecular weight polymers give a rich, creamy foam because of increased viscosity in the surfactant solution as compared to lower molecular weight polymers.     

Synthesis,Surface Activity and Aggregation Behavior of Novel Gemini Pyridinium Amphiphiles

A series of novel pyridinium cationic gemini amphiphiles, 3,3′-(carbonyldiimino)bis (1-n-alkylpyridinium) dibromides, having octyl, decyl, dodecyl, tetradecyl alkyl chains were synthesized. The surface properties and aggregation behavior in aqueous solution were evaluated by surface tension, dynamic light scattering (DLS), and transmission electron microscopy (TEM) measurement. The adsorption at the air/solution interface of all the compounds were quantitative described using the Frumkin model, and the effect of alkyl chain length on surface activity and aggregate behavior was analyzed. It was found that all the gemini amphiphiles possess surface activity and low critical micellization concentration (CMC) values. The values of log CMC depended linearly on the carbon number of the alkyl chains, but the surface tension at the CMC (γ_cmc) showed a minimum for the compound with dodecyl chains. Combinations of DLS and TEM observations showed the existence of vesicles with a broad size distribution in aqueous solution. Meanwhile, vesicles formed below the CMC could be a possible reason for the observed deviation of surface tension curves from the Frumkin model.     

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.     

两亲性无规共聚物MAA-SMA-PEGMA的表面活性研究

利用功能性单体甲基丙烯酸(MAA)、甲基丙烯酸十八烷基酯(SMA)和聚乙二醇甲基丙烯酸酯(PEG-MA)通过自由基共聚,合成了两亲性共聚物Poly(MAA-SMA-PEGMA)。研究了其结构、临界胶束浓度(CMC)和表面张力,探讨了由共聚物与低分子表面活性剂组成的复配体系。结果表明高低分子表面活性剂复配体系在质量比为5∶5后,体系的表面张力和临界胶束浓度都有所降低,接近于低分子表面活性剂。     

Salt Effect on the Solution Properties of Cationic Gemini/Conventional Surfactants in the Presence of the Nonionic Polymer Hydroxypropylmethyl Cellulose

In this article, we report the salt effect on interaction of a water-soluble polymer hydroxypropylmethyl cellulose (HPMC) with the cationic Gemini surfactant (ethane-1, 2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride, 16-E2-16), and also its monomeric counterpart cetyltrimethylammonium chloride (CTAC) using the tensiometric method. Surface tension of the amphiphiles diminished in the presence of the polymer as well as salts; eventually, the polymer gets saturated with the surfactant and there is no further change of surface tension of the solution. Interaction between the polymer and surfactant starts at the critical aggregation concentration (CAC) that is stronger for 16-E2-16 than CTAC. CAC and critical micelle concentration (CMC) values of the surfactant-polymer binary mixtures at various concentrations of the polymer were determined. CAC as well as CMC of 16-E2-16 are considerably lower than CTAC. The inorganic salts (KCl and KBr) have a considerable influence on the polymer–surfactant interaction.     

A Low-Foaming and Biodegradable Surfactant as a Soil-Flushing Agent for Diesel-Contaminated Soil

A novel low-foaming and biodegradable surfactant, consisting of a nonionic head and acyl tail, was synthesized by the base-catalyzed additions of ethylene oxide and propylene oxide to oleic acid. The structure of the new surfactant was elucidated by ¹H- and ¹³C NMR and FT-IR spectroscopies. Measured surface tension was approximately 35.1 mN/m, with a critical micelle concentration (CMC) of 0.026 mM. Both the viscosity and the foaming tendency were relatively low compared to the reported values of similar surfactants. These properties make this surfactant suitable as a cleaning agent for the purpose of remediation of diesel-contaminated soils via soil-flushing. Moreover, the biodegradability test showed that it was nearly completely removed (more than 95%) after seven days, suggesting it is indeed an environmentally-friendly detergent which is an important trait for any remediation reagents. Feasibility tests using diesel-contaminated soils demonstrated its superb potential as a soil-flushing agent to the level comparable to nonionic commercial products.     

Factors affecting oil/water interfacial tension in detergent systems: Nonionic surfactants and nonpolar oils

Because earlier model detergency studies have shown that oil/water interfacial tension is critically important in oil removal processes, factors affecting the interfacial tension between detergent-range nonionic surfactant solutions and paraffin oil have been examined. For a given hydrophobe, equilibrium interfacial tension values increase with the length of the ethylene oxide chain in the hydrophile, because of the attendant decrease in overall surface activity. For a given degree of ethoxylation, commercial nonlphenol ethoxylates reduce interfacial tension more effectively than their secondary alcohol-based counterparts, and these in turn are more effective than commercial primary alcohol ethoxylates. Furthermore, monodisperse primary alcohol ethoxylates reduce interfacial tension more effectively than broad-range ethoxylates with similar cloud points. This observed order of effectiveness is attributed in part to variations in the extent of fractionation that occur as nonionic surfactants divide between the oil and water phases. Equilibrium interfacial tension values produced by commercial nonionic surfactants are significantly more dependent on concentration and temperature than those obtained with monodisperse ethoxylates. However, the time-course for lowering interfacial tension exhibited by monodisperse ethoxylates varies with concentration and temperature to a greater extent than that displayed by commercial products. These findings are accounted for by the combined effects of the changes in relative surface activity and partitioning that occur as the concentration and temperature are varied. An imidazoline-based quaternary fabric softener markedly increases the interfacial tension immediately following phase contact, whereas equilibrium values are only slightly higher in the presence of the softener. Appatently, preferential adsorption of the softener occurs at the interface, followed by adsorption of the nonionic surfactant at the new softener/water interface. Builders and electrolytes have no significant effect on the interfacial tension between aqueous nonionic surfactant solutions and paraffin oil. Terg-O-Tometer results demonstrate the correlation between oil/water interfacial tension and detergency.     

Characterizations of surfactant synthesized from Jatropha oil and its application in enhanced oil recovery

Surfactants are frequently used in chemical enhanced oil recovery (EOR) as it reduces the interfacial tension (IFT) to an ultra‐low value and also alter the wettability of oil‐wet rock, which are important mechanisms for EOR. However, most of the commercial surfactants used in chemical EOR are very expensive. In view of that an attempt has been made to synthesis an anionic surfactant from non‐edible Jatropha oil for its application in EOR. Synthesized surfactant was characterized by FTIR, NMR, dynamic light scattering, thermogravimeter analyser, FESEM, and EDX analysis. Thermal degradability study of the surfactant shows no significant loss till the conventional reservoir temperature. The ability of the surfactant for its use in chemical EOR has been tested by measuring its physicochemical properties, viz., reduction of surface tension, IFT and wettability alteration. The surfactant solution shows a surface tension value of 31.6 mN/m at its critical micelle concentration (CMC). An ultra‐low IFT of 0.0917 mN/m is obtained at CMC of surfactant solution, which is further reduced to 0.00108 mN/m at optimum salinity. The synthesized surfactant alters the oil‐wet quartz surface to water‐wet which favors enhanced recovery of oil. Flooding experiments were conducted with surfactant slugs with different concentrations. Encouraging results with additional recovery more than 25% of original oil in place above the conventional water flooding have been observed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2731–2741, 2017     

The Adsorption of Hydroxyl Mixed Ether Nonionic Polymeric Surfactants at Air/Water and Solid/Water Interfaces: Influence of Surfactant Molecular Structure

This paper reports the adsorption of four nonionic Hydroxyl Mixed Ether (HME) polymeric surfactants at air/water and solid/water interfaces. The characteristics of these nonionic surfactants, including surface tension, critical micelle concentration (CMC) and adsorption onto saponite and Teflon are investigated. At the air/water interface, the surface activity of the HME-surfactants decreases with an increasing degree of ethoxylation. The surface tension results indicate that CMC, surface tension at CMC (γ_CMC), and the minimum surface area per adsorbed HME-surfactant molecule (A _min) all increased with the degree of ethoxylation for surfactants with similar hydrocarbon chain lengths. Additionally, a strong adsorption onto the saponite (synthetic clay) was measured and found dependent on both the degree of ethoxylation and the hydrocarbon chain length. This adsorption was also observed by atomic force microscopy (AFM). On the other hand, the adsorption of HME-surfactants on Teflon was independent of the hydrocarbon chain length.     

Interactions Between a Sulfobetaine-Type Zwitterionic Gemini Surfactant and Fatty Acid Alkanolamide in Aqueous Micellar Solution

The critical micelle concentration (CMC) of 1,2-bis[N-methyl-N-(3-sulfopropyl)-alkylammonium]-ethane betaine (GCS12) was measured using a tensiometric method in the presence of inorganic salts. Inorganic salt has a little impact on the surface tension and CMC of zwitterionic gemini surfactant. The CMC value of GCS12 is 0.07 mmol/L in distilled water, while all CMC values are around 0.04–0.05 mmol/L in the presence of 0.5 % NaCl, 2 % NaCl, and 2 % NaCl + 0.05 % CaCl₂. The interactions between GCS12 and non-ionic surfactant lauric acid diethanolamide (CDA) were investigated by measuring the CMC of their mixtures at different molar ratios. CDA and GCS12 form mixed micelles and exhibit synergism when the mole fraction of CDA is higher than 0.25. Both the steric effect of the head group and GCS12 charge affect the formation and stability of the mixed micelles. Small amounts of GCS12 with a lower CMC penetrate into the micelle of nonionic surfactant with a higher CMC and reduce its degree of hydration inducing an attractive interaction between the two surfactants.     

An Alternative Approach for Determining Critical Micelle Concentration: Dispersion of Ink in Foam

The present work investigates the critical micelle concentration (CMC) of nonionic surfactant solutions using a new approach by monitoring the dirt dispersion (DD) defined as the amount of dirt absorbed by foam using India ink as a model dirt. DD has so far been studied qualitatively by eye estimation. Our quantification studies show that DD increases with increasing surfactant concentration and reaches a maximum. After this, it decreases and becomes very small. The concentration for which DD is maximum corresponds to the CMC, as determined from surface tension measurements. The CMC of natural surfactants obtained from plants Sapindus mukorossi, Albizia procera, Juglans regia, Zephyranthes carinata, and Acacia concinna was determined. The CMC obtained by DD are in reasonably good agreement with those obtained using the surface tension method. The DD method is easy, rapid, and inexpensive and can become an effective tool for estimating the CMC.     

Thermodynamic Parameters and Interfacial Properties of Poly(ethylene glycol)-octyl Sulfosuccinates

Surface tension of a series of poly(ethylene glycol)-octyl sulfosuccinates at different temperatures was measured, and the interfacial properties were investigated in the absence and presence of inorganic salts. Surface tension results indicate that critical micelle concentration (CMC) values of five surfactants (C8-PEG200, C8-PEG400, C8-PEG600, C8-PEG800, and C8-PEG1000) decrease as the molecular weight of polyethylene glycol (PEG) segments and the experimental temperature increases. The surface activity of the C8-PEG series changes with temperature, and the surface tension at the CMC (γ_CMC) of the C8-PEG series decreases initially and then increases as the PEG molecular weight increases. This behavior may be attributed to the dehydration of the surfactant molecules, resulting in the change of hydrophile–lipophile balance for the different EO numbers in the surfactant molecules, which form a different surface energy film at the air–water interface. Negative ΔG_m indicates that the micellization process of these surfactants is spontaneous and an entropically driven process. For the water/alkane interface, these surfactants have low interfacial activity. The interfacial tension (IFT) between these surfactants and alkanes increases first and then decreases with the increase in the molecular weight of PEG segments. After the addition of salt, the interfacial activity of the investigated surfactants increases significantly. The IFT between C8-PEG800 and 10–12 alkanes and between C8-PEG1000 and 12–16 alkanes reaches a low IFT magnitude of 10⁻² mN m⁻¹ in the presence of 0.5% CaCl₂ or the mixed inorganic salts 0.5% NaCl+0.5% CaCl₂.     

Effect of surface active additives on partitioning of proteins and enzymes in poly(ethylene glycol)/dextran aqueous two-phase systems

The effect of anionic (sodium butylbenzene sulfonate, sodium butylmonoglycol sulfate), cationic (tetrabutyl ammonium bromide), nonionic(Tween 20) and amphoteric (proline) surface active additives on the partitioning of proteins and enzymes, such as BSA, lysozyme, glucose oxidase and β-lactoglobulin, in a bipolymeric aqueous two-phase system of polyethylene glycol and dextran has been studied. The partitioning of proteins and enzymes in the aqueous two-phase system is influenced by surface active additives depending upon their structure and charge. The amphiphiles themselves partition unevenly between the two phases. Their effect on protein partitioning can be explained on the basis of electrostatic and hydrophobic interactions. In the presence of ionic amphiphiles, proteins have an affinity for the other phase if an amphiphile carrying a charge of the same sign partitions to that phase. The hydrophobic effect contributes to protein partitioning if the proteins have significant members of surface hydrophobic amino acid residues. © 1998 Society of Chemical Industry