氧乙烯联接链的季铵盐Gemini表面活性剂合成及胶团化特性

合成了含氧乙烯联接链的季铵盐Gemini表面活性剂C12 2 En C12·2Br〔C12=C12H25N+(CH3)2,2=CH2CH2,En=(OC2H4)n,2Br=2Br-,n=1,2,3〕。以电导和稳态荧光法研究了胶团化行为,结果表明,C12 2 En C12·2Br的胶团化能力比其单体表面活性剂十二烷基三甲基溴化铵(C12TABr)高得多,接近于以2个亚甲基构成联接链的C12 2 C12·2Br。胶团聚集数N和表面反离子结合度K0也与C12 2 C12·2Br胶团相当。C12 2 En C12·2Br胶团化过程呈现焓/熵补偿现象,以n=1的胶团最为稳定。     

三联阴离子表面活性剂的合成及其表面化学性能

采用丙三醇、环氧氯丙烷、十二醇及氯磺酸为主要原料合成了三联阴离子表面活性剂Ⅲ-12S.采用元素分析、液相色谱和质谱对产物结构进行表征,通过表面张力的测定研究了其在不同温度和不同反离子浓度下的表面化学性质,并计算了其溶液的胶团化热力学函数.结果表明,表面活性剂Ⅲ-12S具有更低的临界胶团浓度(cmc)和降低表面张力的能力,40℃、c(NaCl)=0.20 mol/L时,最低表面张力(γcmc)和cmc分别为27.54 mN/m和4.898×10-5mol/L.其胶团化热力学函数表明其形成胶团的过程为熵驱动.     

表面活性剂协同效应的研究(英文)

新型表面活性剂的开发研究及现有品种的复配是表面活性剂研究领域中的两个主要方向。对洗涤剂中常用的表面活性剂 :烷基聚氧乙烯醚硫酸钠 (AES)、椰子油酰胺丙基甜菜碱 (KBT)和椰子油二乙醇酰胺 (CDEA)的复配进行了研究。采用滴体积法测定了混合溶液AES/KBT和AES/CDEA的表面张力σ ,再根据σ与溶液浓度C曲线 ,求得溶液的临界胶团浓度cmc、C =cmc时溶液的表面张力σcmc及σ =35mN·m-1时溶液的浓度C35。溶液的起泡性和泡沫稳定性则利用根据Ross -Mile原理自制的装置来测定。实验结果显示 ,在一定混合比时 ,混合溶液的cmc值比相应的任一纯组分的cmc0i 都要低 ,C35也低于纯组分的C035,说明两复配体系均有形成胶团和降低表面张力效率的协同效应。最小cmc值所对应的复配比例 (摩尔比 )为AES/KBT =0 46∶0 5 4,AES/CDEA =0 42∶0 5 8。实验结果还显示 ,混合溶液的起泡性和泡沫稳定性均有改善 ,特别是泡沫稳定性     

N-十二烷基亚氨基二乙酸钠水溶液性质的研究

合成了N-十二烷基亚氨基二乙酸钠(C12H25N(CH2COONa)2)。研究结果表明,分子中的亚氨基在水溶液中极易水解结合质子,使溶液pH随C12H25N(CH2COONa)2浓度增大而增大,羧基则基本处于碱式形态。这种两性分子形式使其水溶液的表面张力曲线具有明确的转折点,而不象月桂酸钠那样出现最低点。该转折点表示临界胶团浓度cmc(=22.1 mmol.L-1)。最低表面张力γcmc和降低水表面张力20 mN.m-1所需的表面活性剂浓度c20分别为44.8 mN.m-1和10.5 mmol.L-1。     

表面活性剂复配规律——第三讲 极性有机物的影响

少量极性有机物的存在能使表面活性剂水溶液的临界胶团浓度（cmc）发生很大变化，也常常增加表面活性剂的表面活性，引起溶液表面张力有最低值的现象。在一些油水体系甚至产生低达10~(-3)-10~(-6)mN·m~(-1)的超低界面张力和形成具有极大稳定性的微乳     

季铵盐双子表面活性剂性能研究

本文测定了四种双子表面活性剂（C12H25（CH3）2N＋（CH2）1N（CH3）2CaH2w＋1和C12H25（CH3）2NCH2CH2OCH2CH2N＋（CH3）2CaH2m＋1（分别记为C12-4-Ca和C12-CH2CH2OCH2CH2-Cm,m=12,18））的表面活性、乳化性能,并计算了表面过剩吸附量（Гmax）和单分予吸附面积（Amia）。结果表咧,合成的删种表面活性剂的临界胶束浓度（cmc）、相应的表面张力（γcmc）、Гmax和Amin基本相差不大。对称的双子表面活性剂的乳化性能优于非对称双子表面活性剂;具有刚性连接基团的乳化性能优于具有柔性连接拱团的双子表面活性剂。并考察了四种表面活性剂对28种植物常见致病菌的抑菌活性。     

季铵盐表面活性剂水溶液表面张力和胶束聚集数

通过体积滴定法测定季铵盐Gemini表面活性剂水溶液的表面张力．由此得到其临界胶束浓度（cmc）,并且利用稳态荧光猝灭法测定胶柬聚集数Nm,进一步说明了此类表面活性剂水溶液很明显的胶团化倾向。     

双子表面活性剂的综述

双子表面活性剂是一类新型的表面活性剂,它是由联结基团通过化学键将两个或多个单体表面活性剂连接在一起形成的表面活性剂。由于其优异的性质越来越受到国内外学者的重视。与传统表面活性剂相比较,双子表面活性剂在降低表面张力、聚集生成胶团、Krafft点和临界胶束浓度(CMC)等性能上都明显更加的优异。文章就它的性能和应用等方面进行介绍。     

联接基链长对非共价键构筑的双子表面活性剂溶液性能的影响

利用非表面活性的十二烷基二甲基叔胺(DA12)和二元羧酸HOOC(CH_2)_(n-2)COOH(n=2,3,4,6,8,10),以非共价键作用的形式构筑了一系列的双子(Pseudogemini)表面活性剂(12-n-12),通过表面张力法及电导率法研究了联接基链长与溶液性能的关系,并考察了联接基链长对乳化性能和润湿性能的影响。实验结果表明,这类表面活性剂水溶液的胶束化过程是热力学自发的熵驱动的放热过程,其临界胶束浓度(cmc)值远远低于传统的单链表面活性剂十二烷基三甲基溴化铵,且有强烈的联接基效应,cmc值在n=4时达到最大值。在这类双子表面活性剂(12-n-12)中,12-10-12的乳化和润湿性能最好。     

二聚表面活性剂的合成与表征

概述了十二烷基二甲基叔胺及其盐酸盐和环氧氯丙烷在温和的条件下合成新型双烷基双季铵盐型阳离子表面活性剂的方法,并比较不同的反应物比例、溶剂和反应温度对反应速率和生成产物的影响,同时还检测了产物的表面张力、临界胶团浓度(cmc)等性质. 实验结果表明,所合成的双季铵盐具有良好的水溶性;与常用的表面活性剂相比,其临界胶团浓度(cmc)要低1～2个数量级,并具有更强的发泡和稳泡性能.     

Aqueous solution properties of disulfide linked gemini and cleaved monomeric thiol surfactants

Monomeric thiol surfactants, [C(n)H(2n+1)N(CH(3))(2)CH(2)CH(2)SH]Br, were produced by the cleavage of gemini surfactant containing a disulfide bond in the spacer chain, [C(n)H(2n+1)N(CH(3))(2)CH(2)CH(2)SSCH(2)CH(2)N(CH(3))(2)C(n)H(2n+1)]2Br. The disulfide bond was completely reduced by the addition of four times moles of dithiothreitol in water at room temperature. The critical micelle concentrations of monomeric surfactants were significantly increased in comparison with original gemini surfactants. The monomeric thiol surfactants were stable in the presence of dithiothreitol, whereas they returned gradually to their original gemini surfactants within several days due to air oxidation in water without dithiothreitol. The micelle formation induced by the disulfide linkage formation was suggested by the fluorescence intensity ratio of pyrene. The time course of decrease in thiol concentration associated with the recovery of gemini surfactants was confirmed by the absorption spectra utilizing the reactions with 4,4'-dithiopyridine.     

Synthesis and Thermodynamic Properties of Rosin-Based Cationic Gemini Surfactants

A series of rosin-based cationic gemini surfactants with different spacer length (n = 2, 3, 4) were synthesized and characterized. Surface activity and micellization parameters including the critical micelle concentration, the degree of counterion dissociation, and thermodynamic functions of micellization in aqueous solutions have been investigated. Free energy perturbation was performed to study the enthalpy-entropy compensation of the synthesized gemini surfactants in aqueous solutions. The experimental results showed that the micellization of rosin-based gemini surfactants in aqueous solutions is a spontaneous and entropy-driven process. The micellization process was found to follow the entropy–enthalpy compensation phenomenon.     

荧光探针法研究新型Gemini表面活性剂在水溶液中的聚集行为

以芘为荧光探针、二苯酮为猝灭剂,用稳态荧光探针法测定了新型Gemini表面活性剂的临界胶团浓度(CMC)、胶团聚集数(Nagg)及胶团微极性.研究了Gemini表面活性剂结构和氯化钠浓度对CMC、Nagg、胶团微极性的影响.结果表明,新型Gemini表面活性剂的CMC比常规表面活性剂的CMC低1—2个数量级.当疏水基碳原子数增加时,CMC依次降低,Nagg增大,胶团微极性减小.当氯化钠浓度增大时,Nagg增大,胶团微极性减小.     

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.     

Microstructure and Phase Behavior of Cationic Gemini/Anionic Polyelectrolyte/Water Ternary System

The microstructure of cationic gemini surfactant 1,6-bis(dodecyldimethylammonium) hexane dibromide [C12H25(CH3)2N-(CH2)6-N(CH3)2C12H25×2Br] (12-6-12×2Br-) and oppositely charged polyelectrolyte poly(acrylic acid, sodium salt) (NaPA) in aqueous solution has been studied by using fluorescence, conductivity measurement, freeze-etching and TEM. The data obtained from fluorescence and conductivity measurement show that micelle-like or complex can form between the gemini surfactant (12-6-12×2Br-) and polyelectrolyte NaPA due to the static electric interaction and hydrophobic forces. Through freeze-etching and TEM, the microstructure of the mixture solution has been studied, which is consistent with the result from micropolarity. Comparing the fluorescence spectrum of system of dodecyltrimethylammonium bromide (DTAB) and NaPA with that of system of gemini surfactant (12-6-12×2Br-) and NaPA, it can be found that the interaction between gemini surfactant (12-6-12×2Br-) and NaPA is stronger than that between DTAB and NaPA. And the phase behavior of (12-6-12×2Br-) and NaPA in aqueous solution has also been detected. It can be shown that the precipitate will transform into gel in higher NaPA concentration.     

Surface Activity and Cleavability of Gemini Surfactants Featuring Hydrophilic Spacer Groups

In this study we prepared and characterized a series of novel ester-linked gemini surfactants, featuring ester bonds in their structures, through the reactions of polyethylene glycol (PEG400) with various fatty acids (C8?CC18). These gemini surfactants exhibit excellent surface activities, as evidenced by their surface tension, wetting power, and low-foaming and buffer abilities. We examine the influence of the concentrations of the ester-linked gemini surfactants on the surface tension, from which we obtain the critical micelle concentrations. Under basic conditions, each of these cleavable surfactants decomposes into a water-insoluble fatty acid and two water-soluble products; in contrast, they are stable under neutral and acidic conditions.     

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.     

Micellization Studies of Dicationic Gemini Surfactants (m-2-m Type) in the Presence of Various Counter- and Co-Ions

Salts have the ability to influence the water activity and self-association of ionic micelles. In the present case, gemini surfactants; ethanediyl-α,ω-bis(dimethyl alkyl ammonium bromide) (referred to as m-2-m, m = 10, 12, 14) are synthesized and their micellization study in aqueous medium in presence of monovalent inorganic (NaBr, NaNO₃, NaCl, KCl, LiCl) and organic salts (NaTos, NaBenz, NaSal) at 303 K is systematically investigated by conductometric and tensiometric methods. All the salts have the tendency to lower the critical micelle concentration of the surfactants. The effect of inorganic salts on the micellization properties has been found to obey the Hofmeister series. Organic salts reduce the CMC more effectively as compared to inorganic salts. The theoretical models of Rubingh and Rosen have been used to compare the results and obtain the interaction parameters, minimum area per molecule, surface excess, mixed micelle composition, activity coefficients and free energies of micellization/adsorption.     

Synthesis and Surface Active Properties of Gemini Cationic Surfactants and Interaction with Anionic Azo Dye (AR52)

A homologous series of new gemini cationic surfactants were synthesized and characterized using micro elemental analysis, FTIR, ¹H-NMR and mass spectra. The surface activities of these amphiphiles were determined based on the data of surface tension. Critical micelle concentration, effectiveness of the surface tension reduction, efficiency of adsorption, maximum surface excess, minimum surface area and critical packing parameter were evaluated. The effect of cationic micelles on solubilization of anionic azo dye, sulforhodamine B (Acid Red 52) in aqueous micellar solution of the synthesized gemini cationic surfactants was studied at pH 6.9 ± 0.5 and 25 °C. The results showed that the solubility of dye rose with increasing surfactant concentration as a consequence of some association between the dye and the micelles. It was also observed that the aggregation of surfactant and dye takes place at a surfactant concentration below the CMC of the individual surfactant. The partition coefficients between the bulk water and surfactant micelles as well as the Gibbs energies of distribution of dye between the bulk water and surfactant micelles were calculated using a pseudo-phase model. The effect of the hydrophobic chain length of Gemini cationic surfactants on the distribution parameters was also reported. The results show favorable solubilization of dye in cationic micelles.     

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.