Synthesis and CMC studies of 1-methyl-3-(pentafluorophenyl)imidazolium quaternary salts

Critical Micelle Concentration (CMC) of sodium dodecyl sulfate (SDS), an anionic surfactant, has been investigated in 30 mM aqueous solutions of 1-benzyl-3-methylimidazolium chloride (1) and 1-methyl-3-(pentafluorophenyl)imidazolium chloride (2). The CMC of SDS is significantly lower in the presence of 2 as compared to that of 1. The decreased CMC of SDS in the presence of 2 is in accordance with its increased hydrophobicity due to the fluorinated side chain. The thermogravimetric analysis of compounds 1 and 2 shows that they are thermally stable up to about 290 degrees C.     

Ionic liquids as modulators of the critical micelle concentration of sodium dodecyl sulfate

Critical micelle concentration (CMC) of sodium dodecyl sulfate (SDS), an anionic surfactant, has been investigated in aqueous solutions of a variety of room temperature ionic liquids (RTILs): 1,3-dimethylimidazolium iodide (Me2IM-I, 2), 1-butyl-3-methylimidazolium chloride (BMIM-Cl, 3), 1-hexyl-3-methylimidazolium chloride (HxMIM-Cl, 4), 1-methyl-3-octylimidazolium chloride (MOIM-Cl), 5, and 1-methyl-3-octylimidazolium tetrafluoroborate (MOIM-BF4, 6). The CMC of SDS is shown to correlate with the nature of the alkyl groups in the RTILs; SDS showed appreciably higher CMCs in presence of ionic liquids 2 and 3, whereas in the presence of ionic liquids 4, 5, and 6 much smaller CMCs were observed. The nature of the gigenions, Cl- or BF4-, has no noticeable effect on the observed CMC values.     

Flow-injection system for determination of critical micelle concentrations of ionic and nonionic surfactants

A practical technique is presented for the rapid, accurate determination of the critical micelle concentrations (CMCs) of ionic and nonionic surfactants. The precision, speed and instrumental simplicity of a flow-injection system are combined with a gradient chamber and flow-through conductance and absorbance detection to produce a system capable of determining the CMC of surfactant solutions in less than 30 min. The exponential response gradients from the resulting system are monitored by a chart recorder and simple manual calculations yield the CMC. The validity of the technique is verified by determination of the CMC values for both ionic (cetyltrimethylammonium bromide and chloride and sodium dodecyl sulfate) and nonionic (Brij-35, Brij-56, Brij-99, Triton X-100) surfactants. The proposed technique does not require the extensive solution preparation, repetitive measurements, complex instrumentation and data manipulation typical of other methods for determining CMCs.     

Ionic liquid-induced changes in the properties of aqueous sodium dodecyl sulfate solution: effect of acidic/basic functional groups

The effects of ionic liquids 1-(2-aminoethyl)-3-methylimidazolium chloride ([MimAE]Cl), 1-carboxylmethyl-3-methylimidazolium chloride ([MimCM]Cl), 1-(2-hydroxylethyl)-3-methylimidazolium chloride ([MimHE]Cl), and 1-ethyl-3-methylimidazolium chloride ([Emim]Cl) on the physicochemical properties of aqueous sodium dodecyl sulfate (SDS) solutions were studied. Compared with [Emim]Cl, the presence of amino group can further facilitate the micellization of SDS, while the opposite result is observed as carboxyl group is imparted. No obvious changes in critical micelle concentration (CMC) and $ {\gamma_{\mathrm{CMC}}} $ values are induced by the neutral hydroxyl group. Only the addition of [MimAE]Cl drastically increases the micellar size. Significant decrease in CMC and increase in micellar size were observed with decreasing pH of [MimAE]Cl solution. The increase in pH of [MimCM]Cl solution results in a slight increase in CMC and decrease in micellar size. ¹H NMR spectra revealed the amino groups are adsorbed at the micellar surface, while the carboxyl groups/carboxylate ions and hydroxyl groups tend to point towards bulk water.     

Interaction of cationic monomer with sodium dodecyl sulfate in dilute aqueous solutions: ESR study

The effect of a cationic monomer (N,N,N,N-trimethyl[methacryloxyethyl]ammonium methyl sulfate) on the formation, structure, and local dynamics of associates resulted from the interaction of the monomer with sodium dodecyl sulfate in aqueous solutions was studied by ESR spectroscopy. In the presence of the monomer, micelles are formed at concentrations much lower than the CMC of the pure surfactant with the monomer molecules that form a condensed layer of counterions around a micelle of sodium dodecyl sulfate. The binding of surfactant micelles with the cationic monomer causes a significant decrease in the local molecular mobility of dodecyl sulfate ions.     

Influence of micellar media on the fluorescence of various benzo- and methyl-quinolizinium salts

The bebaviour of several different micelar systems (anionic, cationic and non-ionic) on the fluorescence of quinolizinium salts is studied. Important factors, such as pH and ionic strength that influence fluorescence parameters, are discussed. Fourteen quinolizinium salts (benzo and methyl derivatives) are examined as fluorescent probes in micellar media. All of them showed a marked increase of fluorescence intensity when sodium dodecyl sulfate solutions of critical micelle concentration (CMC) are added. The presence of non-ionic surfactants did not change the fluorescent emission of the probes. The emission intensity is much decreased when N-cetyl-N,N,N- trimethylammonium bromide concentrations are above the CMC. Changes in pH ido not significantly affect the fluorescence intensity of the benzo derivatives. Increasing the ionic strength decreases the fluorescence. For 9-cyanobenzo[a]phenanthro [9,10-g] quinolizinium chloride, the spectrum changes when the surfactant concentration is high than the CMC thereforre this compound is considered to be a good fluorescent probe in icell     

Emulsion polymerization of vinyl chloride, 2 potassium persulfats decomposition in the presence of PVC latex

The decomposition rate of potassium persulfate (KPS) in aqueous solutions, in the presence of sodium dodecyl sulfate (SDS) and poly(vinyl chloride) latex (PVC) was studied. The dissolved SDS increases the decomposition rate constant (k_d) while the SDS aggregation as micella and/or its adsorption on the polymer hydrophobic surface results in a decreasing k_d. The emulsifier - free surface of the polymer particles increases the decomposition rate. A reaction mechanism based on emulsifier - emulsifier and emulsifier - polymer hydrophobic interactions is put forward.     

Preparation of surfactant anion-selective electrodes with different selectivity coefficients and a trial to determine each component in binary surfactant mixtures

Functional membrane electrodes with different charge densities were prepared from partly cationic poly(vinyl chloride) (PVC) and a plasticizer. The modified PVC polymers were synthesized by the co-polymerization of vinyl chloride (VC) and 3-acrylamido-N,N-dimethylpropylamine (ADPA) in different ratios followed by alkylation of the amine segments with methyl iodide. These membrane electrodes showed a nearly Nernstian response to sodium dodecyl sulfate (SDS) below the critical micelle concentration (CMC). In mixtures of SDS and other surfactants, the electrode response was examined and the selectivity coefficient K for the added surfactant was determined. The charge density of the functional membrane altered K; the greater the charge density of the membrane, the greater the value of K. Two membrane electrodes with different K were used to determine the concentration of each component in a binary surfactant mixture. They determined the concentration of the primary surfactant with reasonable accuracy, but the error in determining the concentration of the secondary surfactant was great. The error analysis indicated that a large difference in K for two electrodes is necessary to determine the concentrations of both components in binary surfactant mixtures with reasonable accuracy.     

Colloidal titration of aqueous zirconium solutions with poly(vinyl sulfate) by potentiometric endpoint detection using a toluidine blue selective electrode.

Zirconium oxy-salts were hydrolyzed to form positively charged polymer or cluster species in acidic solutions. The zirconium hydrolyzed polymer was found to react with a negatively charged polyelectrolyte, such as poly(vinyl sulfate), and to form a stoichiometric polyion complex. Thus, colloidal titration with poly(vinyl sulfate) was applied to measure the zirconium concentration in an acidic solution by using a Toluidine Blue selective plasticized poly(vinyl chloride) membrane electrode as a potentiometric end-point detecting device. The determination could be performed with 1% of the relative standard deviation. The colloidal titration stoichiometry at pH < or = 2 was one mol of zirconium per equivalent mol of poly(vinyl sulfate).     

The Viscous Properties of Anionic/Cationic and Cationic/Nonionic Mixed Surfactant Systems

The behavior of mixed cationic/anionic and cationic/nonionic surfactants solutions have been studied by viscosimetry. The systems studied were sodium dodecyl sulfate (SDS)/cetyltrimethylammonium bromide (CTAB) and CTAB/Brij (polyoxyethylene lauryl ether, n = 10 and 23) in aqueous and sodium chloride solutions. The relative viscosity of single nonionic surfactant solutions is larger than that of SDS or CTAB solutions. It increases with the number of ethylene oxide groups. In the mixed systems, viscosity deviates from ideal behavior. The deviation results from electrostatic interactions. The surfactant mixture composition affects the self-assembled microstructure and rheology. A new mixed system that forms clear micellar solution above CMC was detected. In CTAB/Brij systems, the experimental data also deviate from ideal behavior due to mixed micelle formation and electroviscous effect. This effect is less pronounced than that of SDS/CTAB system and could be suppressed by adding an electrolyte (NaCl).     

The effect of acidity on micellization in dodecyldimethylamine oxide-sodium dodecyl sulfate aqueous mixtures

The effect of acidity on micellization in aqueous solutions of dodecyldimethylamine oxide-sodium dodecyl sulfate mixtures is studied. The CMC values are determined for acidic and nonacidified solutions at 50 °C and different ratios of two surfactants. The measurements are taken using potentiometry, conductometry, and tensiometry techniques. The CMC values are calculated within the framework of a quasi-chemical model of micellization modified with regard to the specific features of the system under consideration. Nonacidified solutions are modeled as a mixture of anionic and nonionic surfactants, whereas acidic solutions are treated as a mixture of anionic and cationic surfactants. The results of model calculations are in satisfactory agreement with the experimental data.     

Effects of addition of short-chain alcohol solvents on micellization and thermodynamic properties of anionic surfactants sodium dodecyl sulfate and sodium dodecyl sulfonate in aqueous solutions

Micellar and thermodynamic properties of anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodecyl sulfonate (SDSn) in aqueous solutions of 5 wt% short-chain alcohols methanol, ethanol, and 1-butanol were investigated by experimental electrical conductivities, densities and sound velocities at 298.15 K. It was found that methanol behaves like a cosolvent and increases the critical micelle concentration (CMC) of both surfactants in aqueous solutions. However, the other investigated alkanols act as a cosurfactant and decrease the CMC by their presence. The values of the degree of counterion association on the micelles of both surfactants in aqueous methanol solution are same as those in pure water, and they decrease with increasing the alkyl chain length of alcohol. Furthermore, the values of the apparent molar volume and isentropic compressibility of the monomeric and micellar forms of the investigated surfactants were obtained from the experimental density and sound velocity data. It was found that the values of the apparent molar properties of both micellar and monomeric forms of the studied surfactants increase by increasing the alkyl chain of the alcohols.     

表面活性剂胶束化物理化学性质研究

通过电导法考查温度和盐浓度对十二烷基硫酸钠(SDS)临界胶束浓度(CMC)的影响,研究表面活性剂形成胶束过程的物理化学性质。根据拟相分离模型求得胶束化热力学函数,并讨论体系电导活化能随温度和SDS浓度变化关系。结果表明:SDS的CMC随温度升高而增加,随氯化钠浓度增大而减小。在热力学上SDS在水溶液中形成胶束是一个自发、放热、熵增的过程;在动力学上,SDS溶液电导率与温度关系符合Arrhenius公式,通过电导活化能信息可揭示离子型表面活性剂形成胶束的机理特征。     

Solubility of ethylene in aqueous solution of sodium dodecyl sulfate at ambient temperature and near the hydrate formation region

The solubility of ethylene in aqueous solutions of sodium dodecyl sulfate (SDS) at different concentrations was measured at temperature 298.2 K and near the hydrate formation region. The effect of SDS on the gas solubility was studied and the solubilities of ethylene in a single micelle under different conditions were evaluated. It was found that the micelle solubilization was obvious, especially in the region near hydrate formation conditions. The CMC of SDS solution was also evaluated based on the solubility vs SDS concentration curves and it was found that it decreased with decreasing temperature.     

Surfactant-sensitive polymeric membrane electrodes

The development and testing is described of surfactant-sensitive electrodes in which the active element is a plasticised polymeric membrane containing a dissolved complex of a cationic and anionic surfactant. Electrodes made with poly(vinyl chloride) membranes plasticised with 40–60% tricresyl phosphate and containing cetyl trimethylammonium dodecyl sulphate are reasonably satisfactory for determining sodium dodecyl sulphate activities below and above the critical micelle concentration. A new class of membrane electrodes has been introduced in which ion-exchange groups are chemically bound to the ends of the poly(vinyl chloride) chains either through the use of an amine as chain transfer agent during polymerisation or by using the SO₃^? radical-anion as polymerisation initiator. The resulting electrodes are specific to anionic or to cationic surfactants but selectivity between different surfactants of the same charge sign is not high. The electrode lifetimes in micellar solutions are much higher than those of previously described electrodes because the electroactive material cannot be lost by solubilisation.     

Determining the Critical Micelle Concentration in O/W Emulsion Using the Rate Constant of Hydrolysis for Benzyl Acetate

An attempt to evaluate the kinetically effective critical micelle concentration CMC of sodium dodecyl sulfate (SDS) in micellar solutions and in O/W emulsions at 40°C and pH 9 utilizing the pseudo first order rate constant of benzyl acetate hydrolysis was implemented. The critical micelle concentration of SDS in micellar solutions was determined by both surface tension measurements utilizing Wilhelmy plate technique and by rate constant of hydrolysis. Hydrolysis reaction of benzyl acetate was monitored in surfactant solutions as well as in o/w emulsions as a function of time. Emulsion droplets were controlled using microfluidizer 110 T and oily droplets were separated from the emulsion by ultracentrifugation at (11,500 rpm or 9,800 g) prior to analysis by high performance liquid chromatography. The value of the critical micelle concentration (CMC) in micellar solutions in the presence of benzyl acetate as determined from the Wilhelmy plate technique was 7.8 × 10^?4 moles/L (CMC in micellar solution was 10 times lower than the value in literature due to use of buffer) while the CMC as determined from the kinetic study was 8.8 × 10^?4 moles/L. In emulsion systems, using 5% mineral oil, the CMC value was 8.6 × 10^?3 moles/L and at 10% oil, the value doubled to 1.73 × 10^?2 moles/L. The above results indicate that kinetics can be used to determine CMC in micellar solutions and in o/w emulsions.     

Miscibility of sodium chloride and sodium dodecyl sulfate in the adsorbed film and aggregate

The adsorption, micelle formation, and salting out of sodium dodecyl sulfate in the presence of sodium chloride were studied from the viewpoint of their mixed adsorption and aggregate formation. The surface tension of aqueous solutions of a sodium chloride–sodium dodecyl sulfate mixture was measured as a function of the total molality and composition of the mixture. Phase diagrams of adsorption and aggregate formation were obtained by applying thermodynamic equations to the surface tension. Judging from the phase diagrams, sodium chloride and sodium dodecyl sulfate are miscible in the adsorbed film at very large composition of sodium chloride and in the salted-out crystalline particle, while they are immiscible in the micelle. The miscibilities in the adsorbed film, micelle, and crystalline particle increase in the following order: particle > adsorbed film > micelle. The difference in miscibility among the oriented states was ascribed to the difference in geometry between the adsorbed film and micelle and to the interaction between bilayer surfaces in the particle.     

Removal of tetramethyl ammonium hydroxide from synthetic liquid wastes of electronic industry through micellar enhanced ultrafiltration

In this paper, the separation of tetramethyl ammonium hydroxide (TMAH) from synthetic liquid wastes of electronic industry is carried out by using a micellar enhanced ultrafiltration (MEUF) process. This treatment represents the first step of an integrated process, aimed at the recovery of TMAH and surfactant and water reuse. The laboratory tests are carried out with an ultrafiltration module using initial solutions having a concentration of pollutant equal to 2?g/L and by adding sodium dodecyl sulfate as a surfactant, at a concentration in the range 4–10?mM/L, that is, under and above its critical micellar concentration (CMC). The experiments have been carried out at a fixed temperature of 25°C. The obtained results showed that very good percentage removals of TMAH are achieved (99%), especially when the surfactant was above the CMC.     

Effects of Added Surfactant on the Dynamic Interfacial Tension Behavior of Acidic Oil/Alkaline Systems

The effects of a ready-made surfactant (sodium dodecyl sulfate) on the dynamic interfacial tension between a model acidic oil (linoleic acid dissolved in paraffin oil) and various aqueous alkaline (NaOH) systems have been studied using pendant drop tensiometry at surfactant concentrations both below and above the critical micelle concentration (CMC). Below the CMC the added surfactant contributes significantly to a further reduction of interfacial tension of the reacting acid/alkaline system, whereas above the CMC the added surfactant plays an important role in damping the dynamic trends observed for the reactive system alone. Copyright 2001 Academic Press.     

可见吸收光谱线型参数分析法测定十二烷基硫酸钠临界胶束浓度

于浓度相同的结晶紫（CV）溶液中,加入不同浓度的十二烷基硫酸钠（SDS）组成一系列含有相同浓度CV和不同浓度SDS的混合溶液。在可见光区内对每一混合溶液测定其吸收值时,可见随SDS浓度的逐步递增,在CV-单聚体吸收峰的吸收值逐渐减少;而在CV-二聚体吸收峰的吸收值逐渐增加,且随CV-二聚体浓度增加而出现的CV-二聚体与CV-单聚体的吸收光谱线相互严重重叠,光谱形状也发生渐变。运用分光光度计所配备的Origin 7．5软件中储存的高斯多峰拟合法,可自动进行重叠光谱的解析和各光谱参数（包括y0,A1,A2,ω1,ω2,xc1及xc2）的拟合计算。文中还证示,每一参数与SDS浓度之间有明显的相关性,在两者之间所作的曲线上可找到明显的转折点,与转折点相对应的、在横坐标上的SDS浓度值即为SDS的临界胶束浓度（CMC）值。文中首次报道了用吸收光谱的半峰宽对SDS浓度作图所得曲线上的转折点求得SDS的CMC值。