Effects of Metal Ions on the Micellization of Ionic Surfactants

The effect of metal ions (Cu(II), Zn(II), Co(II), Ni(II), La(III), Fe(III)) on the critical micelle concentration (CMC) of ionic surfactants (sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB)) were investigated at 25±0.1°C, μ = 0.1 M (KNO₃), using conductivity method in this paper. A series of general empirical expressions about the relationship between the CMC values for SDS and CTAB and the concentrations of metal ions have been derived. The results showed that the CMC values for both SDS and CTAB decreased with increasing the concentrations of metal ions. This can be interpreted by the counterion effect and the entropy driving effect.     

添加中低浓度离子液体[bmim][BF4]对吐温-20临界胶束浓度和胶束结构的影响

添加离子液体会对表面活性剂在水溶液中的聚集行为产生重要影响。本文研究了吐温-20在中低浓度离子液体四氟硼酸1-丁基-3-甲基咪唑鎓([bmim][BF_4])中的胶束化行为。随着[bmim][BF_4]浓度(cIL)从0增加到0.2mol·L~(-1),吐温-20的临界胶束浓度逐渐增大。相比cIL0.05mol·L~(-1),在cIL0.05mol·L~(-1)时加入[bmim][BF_4]使吐温-20临界胶束浓度增大得更加显著。吐温-20胶束聚集数随着离子液体浓度的增加而逐渐减小,这一结果也说明加入离子液体会对吐温-20胶束的生成有抑制作用。吐温-20胶束化热力学研究表明,吐温-20在不同浓度离子液体中的胶束化是熵、焓共同驱动,并具有熵-焓补偿性。随着离子液体浓度的增加,吐温-20胶束平均粒径和胶束微粘性均表现出先增大后减小的变化,在cIL=0.05mol·L~(-1)时达到最大值。     

表面活性剂胶束化过程中对芘的荧光猝灭

本文研究了烷基三苯基 盐及N-烷基吡啶盐胶束化过程中对芘的荧光猝灭。讨论了表面活性剂分子在水溶液中的优势构型以及芘在胶束中的增溶位置。简单说明了胶束增敏发光分析的机理。研究表明,胶束形成前后荧光猝灭均符合Stern-Volmer方程。     

Mixed Micellization of Dimeric (Gemini) Surfactants and Conventional Surfactants

The aqueous solutions of mixtures of various conventional surfactants and dimeric anionic and cationic surfactants have been investigated by electrical conductivity, spectrofluorometry, and time-resolved fluorescence quenching to determine the critical micelle concentrations and the micelle aggregation numbers in these mixtures. The following systems have been investigated: 12-2-12/DTAB, 12-2-12/C(12)E(6), 12-2-12/C(12)E(8), 12-3-12/C(12)E(8), Dim3/C(12)E(8), and Dim4/C(12)E(8) (12-2-12 and 12-3-12=dimethylene-1,2- and trimethylene-1,3-bis(dodecyldimethylammonium bromide), respectively; C(12)E(6) and C(12)E(8)=hexa- and octaethyleneglycol monododecylethers, respectively; Dim3 and Dim4=anionic dimeric surfactants of the disodium sulfonate type, Scheme 1; DTAB=dodecyltrimethylammonium bromide). For the sake of comparison the conventional surfactant mixtures DTAB/C(12)E(8) and SDS/C(12)E(8) (SDS=sodium dodecylsulfate) have also been investigated (reference systems). Synergism in micelle formation (presence of a minimum in the cmc vs composition plot) has been observed for the Dim4/C(12)E(8) mixture but not for other dimeric surfactant/nonionic surfactant mixtures investigated. The aggregation numbers of the mixed reference systems DTAB/C(12)E(8) and SDS/C(12)E(8) vary monotonously with composition from the value of the aggregation number of the pure C(12)E(8) to that of the pure ionic component. In contrast, the aggregation number of the dimeric surfactant/C(12)E(8) mixtures goes through a minimum at a low value of the dimeric surfactant mole fraction. This minimum does not appear to be correlated to the existence of synergism in micelle formation. The initial decrease of the aggregation number of the nonionic surfactant upon addition of ionic surfactant, up to a mole fraction of ionic surfactant of about 0.2 (in equivalent per total equivalent), depends little on the nature the surfactant, whether conventional or dimeric. The results also show that the microviscosity of the systems containing dimeric surfactants is larger than that of the reference systems. Copyright 2001 Academic Press.     

季铵盐型Gemini表面活性剂的胶束化动力学研究

采用停流法并结合Aniannson-Wall理论, 研究了联接基为(CH2)2, (CH2)3, (CH2)4和(CH2)6的季铵盐型Gemini表面活性剂胶束的形成-破坏过程. 动力学的研究结果表明, 胶束形成-破坏过程的弛豫时间(τ2)与联接基的长度、表面活性剂的浓度、反离子的浓度以及温度有关. 随联接基长度的增加, 季铵盐型Gemini表面活性剂胶束形成-破坏过程的弛豫时间缩短. 当温度高于293 K时, 随着反离子浓度的增加, 1/τ2将出现一个最低值. 根据核化焓结果提出了不同的联接基长度的季铵盐型Gemini表面活性剂具有不同的胶束形成-破坏过程的机理.     

Some Thoughts Regarding Theoretical Aspects of the Corrin-Harkins Relation and the Micellization Product of Ionic Micelles

The dependence of the stability of ionic micelles on the ionic strength of the medium is examined analytically without recourse to any explicit expression of the surface potential of micelles. The present study is based on the idea developed by Evans, Mitchell, and Ninham (D. F. Evans, D. J. Mitchell, and B. W. Ninham, J. Phys. Chem. 88, 6344 (1984)) that the interfacial free energy at the water/hydrocarbon core interface is independent of the ionic strength of the medium. The Corrin-Harkins (C-H) relation, a linear relation between the logarithm of the critical micelle concentration (cmc) and the logarithm of the counterion concentration n(C), is obtained in the range of n(C) where the salting-out effect is negligible, under the condition that the area per monomer on the micelle surface decreases very weakly with n(C). The "micellization product" of the charged pseudophase model of ionic micelles is discussed. The linear dependence of the surface potential of ionic micelles on n(C) is derived while a part of the effects of salt on the micelle size/shape is allowed. Copyright 2001 Academic Press.     

Determination of the Critical Micelle Concentration of Cationic Surfactants by Capillary Electrophoresis

The determination of the critical micelle concentration (CMC) of cationic surfactants by capillary electrophoresis was demonstrated. In this study, tetradecyltrimethylammonium bromide (TTAB) and dodecyltrimethylammonium bromide (DoTAB) were selected as cationic surfactants and propazine was chosen as test solute. In the evolution of the effective electrophoretic mobility of propazine as a function of surfactant concentration, a dramatic change in slope at a particular concentration is a good indication of the CMC of this surfactant. The CMC values determined experimentally were further confirmed by a curve-fitting approach. Simulation of the electrophoretic mobility curves as a function of surfactant concentration in both micellar electrokinetic chromatography and capillary zone electrophoresis using cationic surfactants as an electrolyte modifier was performed for propazine, and the intersection of these two mobility curves allowed us to precisely predict the CMC of the surfactant. The CMC values determined for TTAB and DoTAB are 1.6 ± 0.1 and 11.0 ± 0.1 mM, respectively, in the case of an electrolytic solution consisting of 70 mM phosphate buffer at pH 6.0. Moreover, the applicability of the electroosmotic mobility as a parameter for the determination of the CMC was examined.     

Experimental and Theoretical Study of Two Pyridinium-Based Ionic Liquids

Thermophysical properties of two pyridinium-based ionic liquids, 1-ethyl-2-methylpyridinium bis(trifluoromethylsulfonyl)imide and 1-propyl-2-methylpyridinium bis(trifluoromethylsulfonyl)imide, have been measured from 278.15 to 323.15?K, with a temperature step of 2.5?K. The properties measured were: densities, speeds of sound, refractive indices, surface tensions, isobaric molar heat capacities, electrical conductivities and viscosities. Thermal properties were also recorded in the temperature range from 100 to 320?K. From the experimental results coefficients of thermal expansion, isentropic compressibilities, molar refraction and surface enthalpies and entropies have been determined. Moreover, a theoretical study has been performed using ab initio calculations, level of theory HF/6-31G(d). From this study, we have obtained qualitative information about the magnitude and the directionality of the cation?Canion interactions which allows a better understanding of the physico-chemical properties of these ionic liquids.     

Influence of Ionic Surfactants on Tetrabromophenylfluorone Ionic Associates

Stability constants of ionic associates of a hydroxyxanthene dye, tetrabromophenylfluorone, with a series of organic cations were determined spectrophotometrically. The possibility of quantitative determination of anionic surfactants (alkyl sulfates) in an aqueous solution in the form of a dye anion associate with tetrabutylammonium cation was considered.     

多种类表面活性剂临界胶束浓度定量构效关系

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靠的预测结果, 其预测结果相关性系数R²(training set)=0.9295, 相对标准偏差ARD(training set)=8.20%, R²(testing set)=0.9257, ARD(testing set)=6.76%. 与文献中模型预测结果的对比表明, 本工作在稳定性和可靠性上均有显著改善.     

对称正、负离子表面活性剂的胶团化和表面吸附自由能

根据所建议的表面活性剂疏水碳氢基在水溶液中自卷曲的分子构型和碳氢链/水界面自由能降低模型导出了对称正-负离子表面活性剂胶团化和表面吸附自由能及疏水自由能公式, 计算结果支持上述理论模型。     

拥挤环境中表面活性剂胶束化过程的低场核磁共振研究

利用长弛豫低场核磁共振(LF-NMR)方法研究了由聚乙二醇(PEG)构建的拥挤溶液环境中表面活性剂的聚集行为。通过Carr-Purcell-Meiboom-Gill(CPMG)脉冲序列所得的回波数据及反演拟合数据对不同的表面活性剂-PEG体系进行分析,结果发现:不同分子量和不同浓度的PEG溶液可用低场核磁共振方法进行区分;高浓度的PEG溶液中均能监测到胶束形成过程,而较低浓度的PEG溶液不利于其胶束化过程监测;NaCl对含有离子型表面活性剂体系的影响较为明显,而对含有非离子型表面活性剂的体系几乎无影响。该研究丰富了低场核磁共振弛豫技术在表面活性剂胶束表征过程中的应用,同时对理解生物体系中分子的自组装及功能也具有重要意义。     

Prediction on Critical Micelle Concentration of Nonionic Surfactants in Aqueous Solution： Quantitative Structure-Property Relationship Approach

IntroductionCriticalmicelleconcentration (cmc)ofsurfactantsinaqueoussolutionisoneofthemostusefulparametersforcharacterizingthepropertiesofsurfactants.Overaverynarrowconcentrationrangearoundthecmctransitionsoftheexistenceofsurfactantsoccurfrommonomer ,premicel lartomicellar .Andcompanyingthesetransitions ,manyotherimportantpropertiesofsurfactantsolution ,suchassurfacetension ,interfacialtension ,conductivity ,osmoticpressure ,detergency ,emulsification ,foamingandsoon ,alsochangesharplyatthepoi…     

定量结构-性质相关原理在阴离子表面活性剂临界胶束浓度预测中的应用

利用定量结构-性能相关（QSPR）原理，建立起了8类不同结构，计40个阴离子 表面活性剂临界胶束浓度（cmc）的定量模型。所得到的最佳模型包括：分子总能 量（E_T）、分子生成热（ΔH_f）、分子偶极矩（D）、前线分子轨道能量（E_ (LUMO),E_(HOMO)）及憎水基0级Kier & Hall指数（KHO），计6个描述符，复相关 系数R~2 = 0.9778。     

Ionic Complexes of Polyacids and Cationic Surfactants

Comb-like ionic complexes were prepared from polyuronic acids (pectinic and alginic acids) and alkyltrimethylammonium surfactants bearing linear alkyl chains with 18, 20 and 22 carbon atoms. In the condensed state, these complexes were able to self-assemble in ordered structures which were thermally stable up to ∼200 °C. The complexes were analysed by DSC and WAXS/SAXS and compared to their analogous made from poly(γ-glutamic acid). They all adopt a biphasic layered structure in which the main chain and the alkyl side chain alternate with a nanometric periodicity. Alkyl side chains were partially crystallized in these complexes and they show reversible melting at temperatures within the 60-80 °C range depending on the length of the polymethylene segment.     

Micellization and Adsorption to Carbon Black of Polyisobutylene-Based Ionic Liquids

Ionic liquid-terminated polyisobutylene (PIB-IL) dispersants suitable for stabilization of carbonaceous deposits found in automotive lubricating oils were derived by the quaternization of tertiary amines (1-methyl-imidazole, pyridine, and isoquinoline) with primary bromide-terminated PIB. Characterization of PIB intermediate and PIB-IL dispersants was carried out by nuclear magnetic resonance, gel-permeation chromatography, thermogravimetric analysis (TGA), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and differential scanning calorimetry. PIB-IL micellization in dodecane and characteristics thereof (hydrodynamic radius, aggregation number, and critical micelle concentration) were investigated by static (SLS) and dynamic light scattering; whereupon, the self-association of PIB-IL was found to be highly sensitive to anion hydrophobicity. Qualitative adsorption of PIB-IL onto carbon black was confirmed by Fourier transform infrared and TGA measurements. Using Langmuir adsorption studies, the affinity for and adsorption to carbon black of PIB-IL were characterized. PIB-IL adsorption onto carbon black occurred via cation–π interactions and was identified to be highly dependent on the molar volume of the cation and independent of the anion. From the parameters obtained by the Langmuir adsorption isotherms, the spatial arrangement of PIB-IL on the carbon black surface was elucidated, in which all adsorbed PIB-IL were determined to exist in the elongated brush regime. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 280–299     

Modelling of the Critical Micelle Concentration of Cationic Gemini Surfactants Using Molecular Connectivity Indices

Modelling of the critical micelle concentrations (cmc) using the molecular connectivity indices was performed for a set of 21 cationic gemini surfactants with medium-length spacers. The obtained model contains only the second-order Kier and Hall molecular connectivity index. It is suggested that the index ² χ includes some information about flexibility. The obtained model was used to predict log₁₀ cmc of other cationic gemini surfactants. The agreement between calculated and experimental values of log₁₀ cmc for the gemini surfactants that were not used in the correlation is very good.     

Determination of Critical Micelle Concentration of Anionic Surfactants by Ligand Exchange Micellar Electrokinetic Chromatography

CMC (Critical Micelle Concentration) is an important parameter of surfactant. It has been reported that it changes with ionic strength, temperature, additives, etc. Therefore, it could not be overestimated to develop the determination method of CMC of surfactants. Recently,current method using CE instrument and CE method have been reported. This paper presents an new method for determining CMC of anionic surfactants by ligand exchange micellar electrokinetic chromatography.