表面张力法探究温度对表面活性剂临界胶束浓度的影响

临界胶束浓度是表面活性剂的一个重要性质。本文用表面张力法测定了非离子型表面活性剂的临界胶束浓度。结果表明,随着温度升高,非离子型表面活性剂的临界胶束浓度反而会降低。对温度影响表面活性剂临界胶束浓度的机理进行了初步分析。     

多元表面活性剂复配的分子热力学模型研究

表面活性剂在实际工业生产中有着广泛应用,一般多为多种表面活性剂的复配体系,利用不同组分的特性,使得复配体系具有比单一表面活性剂更优越的性能,而多元表面活性剂复配机理仍不是很清楚。采用实验与理论模型相结合的方法,研究混合表面活性剂各组分间的协同效应。首先以Flory-Huggins理论为基础,推导了多元表面活性剂体系的分子热力学模型,通过二元系实验数据关联出两两相互作用参数,可对多元体系临界胶束浓度(cmc)与混合表面活性剂胶束相组成进行预测,三元表面活性剂复配体系模型计算结果与实验值吻合较好。     

期刊文献

正多种类表面活性剂临界胶束浓度定量构效关系朱志臣,王强,贾青竹,汤红梅,马沛生摘要:表面活性剂的临界胶束浓度(cmc)是个非常重要的物质特性参数,cmc在研究表面活性剂的工业应用和生物利用方面发挥着关键作用。本工作提出了一个新的拓扑指数——扩展距离矩阵,建立了一个稳定的构效关系模型,并对175种表面活性剂的临界胶束浓度进行了计算预测。结果表明,基于新的拓扑指数建立的构效关系模型计算临界胶束浓度能给出稳定可     

长链离子液体临界胶束浓度研究

采用毛细上升法测定[Cn MIm]Br(n=12,14,16)3种长链离子液体与十二烷基硫酸钠(传统阴离子表面活性剂)的表面张力,通过表面张力拐点得到临界胶束浓度。结果表明,长链离子液体与传统表面活性剂临界胶束浓度相当;在临界胶束浓度下,长链离子液体表面张力相差不大,且都略小于传统表面活性剂,则其表面活性优于传统阴离子表面活性剂。     

长链离子液体临界胶束浓度研究

采用毛细上升法测定[Cn MIm]Br(n=12,14,16)3种长链离子液体与十二烷基硫酸钠(传统阴离子表面活性剂)的表面张力,通过表面张力拐点得到临界胶束浓度。结果表明,长链离子液体与传统表面活性剂临界胶束浓度相当;在临界胶束浓度下,长链离子液体表面张力相差不大,且都略小于传统表面活性剂,则其表面活性优于传统阴离子表面活性剂。     

GSS362/TX-100复配体系在水中的溶液行为研究

研究了1,3-丙二醇双子琥珀酸二异辛酯磺酸钠(GSS362)和辛基酚聚氧乙烯醚(TX-100)复配物在水中的表面性质和胶束化行为,并对理想混合临界胶束浓度以及混合体系中各组分在表面吸附层和胶束中的组成、相互作用参数和热力学参数进行分析计算。结果表明,复配物在水溶液中不存在协同效应,但是TX-100的加入明显降低了GSS362的临界胶束浓度,混合胶束的形成为自发过程,胶束中GSS362与TX-100分子具有较弱的相互作用,胶束中富含非离子表面活性剂TX-100。     

基于正规溶液理论计算三元混合表面活性剂的临界胶束浓度

随着溶液pH的降低,TX-100/N,N-二甲基十二烷基氧化胺二元表面活性剂混合体系变为三元表面活性剂混合体系;利用滴体积法测定了不同pH时该混合体系的临界胶束浓度,并利用正规溶液理论计算了该三元表面活性剂混合体系的临界胶柬浓度,计算结果在一定范围内与实验较好地相符.     

离子液体水溶液临界胶束浓度的研究进展

离子液体作为表面活性剂或反应介质已引起人们的广泛关注。本文介绍了离子液体在水溶液中的自聚合行为,尤其是离子液体水溶液临界胶束浓度的确定。并介绍了几种不同确定离子液体水溶液的临界胶束浓度的方法。     

用流变学方法研究铝离子存在时阴离子表面活性剂胶束的生长和结构(英文)

表面活性剂溶液的流变行为是影响表面活性剂应用的重要因素之一。用流变学方法 ,通过测定溶液在不同浓度和温度时的剪切粘度和应力研究了铝离子存在时阴离子表面活性剂十二烷基聚氧乙烯 (3)硫酸钠 (AES)胶束的生长和结构。结果表明 ,升高表面活性剂和盐的浓度或降低温度都可以促进胶束的生长 ,并且形成虫状胶束和网络结构 ;溶液的流变行为不符合Maxwell模型 ,表现为非线性粘弹性和非牛顿流体     

表面活性剂／大分子混合溶液的流变性

本报道了不同表面活性剂／大分子混合体系流变性随表面活性剂浓度的变化规律。离子型表面活性剂使非离子大分子表现出聚电解质的粘度行为，大分子的存在也可使棒状胶束转化为球状胶束，从而使粘度降低。     

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.     

Interfacial mass transfer in extraction of amino acid by aliquat 336 in organic phase

Reactive extraction of L -phenylalanine from alkaline aqueous solution into xylene in the presence of tri-octyl-methyl-ammonium chloride (ALIQUAT 336) as complexing agent was studied using a stirred transfer cell. The study investigated the effects of carrier concentration and temperature on mass transfer rates. Transfer rate across the interface in the presence of surfactant molecules was also studied. A two-film model was proposed by considering film mass transfer resistances at the aqueous and organic phases. The model predicted adequately the experimental time-concentration data at different carrier concentrations and temperatures. The model was modified to take into account the presence of surfactant in the organic phase.     

基于微扰理论的表面活性剂水溶液表面状态方程

应用微扰理论并借鉴二维气体理论的处理方法,建立了非离子表面活性剂水溶液的表面状态方程。将微扰理论与压力方程相结合,建立了离子表面活性剂水溶液的表面状态方程。运用提出的状态方程,分别对6种烷基聚氧乙烯醚、辛基酚聚氧乙烯醚、十二烷基硫酸钠等表面活性剂水溶液的表面压数据进行了关联,并利用关联所得的参数预测了其他种类的烷基聚氧乙烯醚及辛基酚聚氧乙烯醚和十二烷基硫酸钠水溶液在不同温度下的表面压。关联和预测的精度均较高,结果令人满意。     

Solubilisation of dyes by surfactant micelles. Part 3; A spectroscopic study of azo dyes in surfactant solutions†

A spectroscopic study (UV–vis and adsorption) has been made of the interactions of select model azo dyes with a range of surfactant types or their mixtures both above and below their respective critical micelle concentrations. All surfactants inhibit adsorption of the dyes to cotton above their critical micelle concentrations due to incorporation in micelles. However, formation of 1;1 complexes between dyes and cationic or zwitterionic surfactants in sub‐micellar regions results in enhanced deposition on cotton. It is shown that attractive or repulsive electrostatic interactions play a key role in dye binding to micelles. Unusually, spectra of complexes formed between the dye and cationic surfactant are typical of those of the azo tautomeric form as opposed to the hydrazone form that is prevalent in aqueous media. Addition of anionic surfactant to micellar solutions of nonionic or zwitterionic surfactants results in successive displacement of dye from the respective micelles, i.e. binding is competitive.     

Interaction Between Ionic Liquids and Gemini Surfactant: A Detailed Investigation into the Role of Ionic Liquids in Modifying Properties of Aqueous Gemini Surfactant

Tuning physicochemical properties of aqueous surfactant solutions comprised of normal or reverse micelles by external additives is of utmost importance due to the enormous application potential of surfactant‐based systems. Unusual and interesting properties of environmentally benign ionic liquids (IL) make them suitable candidates for this purpose. To understand and establish the role of IL in modifying properties of aqueous gemini surfactants, we studied the effect of the IL, 1‐hexyl‐3‐methylimidazolium bromide ([Hmim][Br]) and 1‐octyl‐3‐methylimidazolium bromide ([Omim][Br]) on the properties of the aqueous cationic gemini surfactant 1,6‐hexanediyl‐α,ω‐bis(dimethyltetradecyl)ammonium bromide (14‐6‐14,2Br^?). The behavioral changes were investigated by measuring the critical micelle concentration (CMC) using electrical conductance, surface tension, dye solubilization and fluorescence probe measurements at 298.15 K. It was observed that the CMC of 14‐6‐14,2Br^? gemini surfactant decreases with addition of IL, thus favoring the micellization process. An increase in micellar size was observed at lower IL concentration using dynamic light scattering, with a decrease in aggregation number (N_agg) determined from fluorescence probe quenching measurements. It is noteworthy that the extent of modulation of the micellar properties is different for both the IL due to their structural differences. IL behave like electrolytes at lower concentrations and cosurfactants at higher concentrations and form mixed micelles with the cationic gemini surfactant showing an increase in N_agg.     

Electropolymerization of ethylene dioxythiophene (EDOT) in micellar aqueous solutions studied by electrochemical quartz crystal microbalance and surface plasmon resonance

Electropolymerization of 3,4-ethylene dioxythiophene (EDOT) on gold electrodes was studied in situ by means of an electrochemical quartz crystal microbalance (EQCM) and by surface plasmon resonance spectroscopy (SPR) using aqueous micellar monomer solutions. Electrodeposition from micellar solutions performed by cyclic voltammetry (CV) displayed an enhanced rate as compared to surfactant concentrations lower than the critical micelle concentration (cmc) or in surfactant-free monomer solutions. EQCM data indicate the occurrence of additional film growth during the reductive scan to large negative potentials which does not occur in electropolymerization experiments using potentiostatic pulses or cyclovoltammetric cycles with less negative potential scans. Our results further suggest that in the case of the anionic surfactant the oxidation potential of the monomer is lowered even at surfactant concentrations below the cmc. AFM investigations show a slightly enhanced roughness of the films obtained from micellar monomer solutions.     

Activity of horseradish peroxidase in aqueous and reverse micelles and back‐extraction from reverse‐micellar phases

Studies on the activity of the enzyme horseradish peroxidase (HRP) have been carried out in micellar as well as reverse‐micellar media. The activity of the enzyme was studied in the presence of different classes of surfactants – ionic as well as non‐ionic. In aqueous media, the activity of the enzyme varied depending on whether the concentration of the surfactant used was above or below the critical micellar concentration (CMC). The enzyme was also studied in reverse‐micellar systems. HRP was introduced into the reverse micellar phase by the injection method and its activity within the reverse micelles was determined. The effect of water to surfactant ratio (W_o) on activity within reverse micelles was studied, and an almost two‐fold increase in activity was seen when the enzyme was encapsulated within reverse micelles of aqueous phase fractional hold‐up (?) of 0.0072 (v/v) consisting of sodium bis‐(2‐ethylhexyl) sulfosuccinate (AOT) in isooctane at a W_o of 20. The activity of HRP was measured over a wide range of AOT concentrations having different W_o values. Back‐extraction of HRP from these reverse micelles was carried out at varying ionic strengths of phosphate buffer. Back extraction was found to be highest at pH 7.0 in 40 mol m^?3 phosphate buffer and 100 mol m^?3 sodium chloride. © 2001 Society of Chemical Industry     

Insights Into Molecular Interaction of Antitumor Drug Mitoxantrone With Anionic Surfactant Sodium Dodecyl Sulfate at Different Temperatures

A study of the interaction of antitumor drug mitoxantrone with anionic surfactant sodium dodecyl sulfate (SDS) has been carried out by UV–Vis absorption spectroscopy at submicellar and micellar surfactant concentrations, pH 7.4 and 10, and over a temperature range of 293.15–323.15 K. The variation of the monomer drug absorbance as a function of SDS concentration indicates, at pH 7.4 and all investigated temperatures, two definite processes: process I in the submicellar range, attributed to the electrostatic interaction between mitoxantrone and SDS monomers; and process II in the micellar range, when the drug is incorporated into SDS micelles in monomer form. At pH 10, the results have indicated only the process II at micellar SDS concentrations. The monomer absorbance changes occurring as a result of the interactions between mitoxantrone and SDS were rationalized in terms of binding constant, micelle/water partition coefficient, and the corresponding thermodynamic parameters for binding and partitioning processes. Thermodynamic parameters indicate that at pH 7.4 both binding process of mitoxantrone to SDS and partition process of mitoxantrone between micellar and bulk aqueous phases are spontaneous and enthalpy controlled, while at pH 10 both processes are spontaneous and entropy controlled.     

Solubilisation study of water‐insoluble dye in cationic single/dimeric surfactant micelles: effect of headgroup,non‐polar tail,and spacer chain in aqueous and salt solution

The solubilisation of hydrophobic azo dye Orange OT in aqueous/salt solution in several cationic surfactant micelles was studied using UV‐vis spectroscopy. An attempt was made to correlate dye solubilising strength with adsorption/micellar characteristics. In our experiments we determined the change in solubilisation of hydrophobic dye when added to an aqueous solution of oppositely charged quaternary‐salt‐based cationic surfactants (conventional and gemini) and remarked on the probable location of the solubilised dye in the surfactant micelle. Results highlight the onset of dye solubilisation around the critical micelle concentration of each surfactant, which is influenced by the non‐polar tail, spacer, and polar headgroup, while no dye could be solubilised at concentrations below the critical micelle concentration. Orange OT solubilised almost linearly with increase in surfactant concentration at and above the critical micelle concentration. The change in colour intensity of the dye (darker below the critical micelle concentration, lighter at and above the critical micelle concentration) could be attributed to dye–surfactant interactions. Further dye solubilisation was observed in the presence of salt.     

Flow behavior of sucrose stearate/water systems

The aim of this work was to carry out a rheological study of aqueous systems containing a nonionic surfactant derived from sugar. The compositions studied ranged from the micellar region up to the occurrence of fully developed liquid crystals. This study was carried out at 50°C. Systems up to 2% (wt) sucrose stearate exhibited a power-law decrease in the steady-state apparent viscosity with shear rate. At higher sucrose stearate concentrations, the flow curves exhibited two well-defined regions depending on shear rate, so that the apparent viscosities fitted the Carreau model A [Carreau, P.J., D. De Kee and M. Daroux,Can. J. Chem. Eng. 57:135 (1979)]. The existence of three composition ranges is proposed. An increasingly stronger micellar structure, as surfactant concentration rises, extends up to 10% (wt) sucrose stearate. Between 15% and 35% (wt) sucrose stearate, the results obtained are consistent with the occurrence of a lamellar liquid-crystal dispersion in an isotropic micellar solution. The liquid crystalline content in the dispersion steadily increases with surfactant concentration up to reaching a fully developed lamellar liquid crystal at 40% (wt) sucrose stearate.