季铵盐二聚表面活性剂C12-S2-C12·2Br复配体系在氯仿中形成反胶团的增溶水状态

采用近红外光谱技术,研究了季铵盐Gemini表面活性剂C12-S2-C12.2Br/氯仿体系中反胶团的增溶水状态,使用Peakfit解峰技术,将水的近红外光谱分为3个亚带,分别对应分散于溶剂中的水、反胶团中的类似本体水和结合水。将以上3种状态的水换算成每个表面活性剂分子对应的各种状态水分子数,即分散在溶剂中的水ns、类似本体水nf和结合水nb。向C12-S2-C12.2Br/氯仿体系中加入不同头基的离子型表面活性剂十二烷基三甲(乙)基溴化铵(DTAB、DTEB),发现随着添加剂摩尔分数αA的增大,ns和nb增大,nf减小。加入非离子表面活性剂聚乙二醇辛基苯基醚(OP-10),随着αA的增大ns减小,nb增大,nf略有增大趋势。可见加入表面活性剂头基的大小、所带电荷以及亲水性等均会对反胶团的增溶水能力和状态产生影响。     

NaBr对C12-s-C12•2Br/氯仿体系中反胶团增溶水能力的影响

近红外(NIR)光谱技术可用于表征氯仿体系中反胶团增溶水的能力. 对于C12-s-C12•2Br (s=2, 3, 4, 5, 6, 8)系列, 不论体系是否含有NaBr电解质, 由于具有较短联接链的表面活性剂易形成较大的反胶团, 其增溶水的能力随着联接链长度增加而降低. 与未含NaBr电解质的体系相比, 当体系中存在NaBr电解质时所形成的反胶团增溶水能力降低.     

反胶团相转移法提纯酵母脂肪酶

反胶团相转移法是80年代兴起的一种新型分离技术，它利用表面活性剂分子在有机溶剂中自发形成的反向胶团（反胶团），在一定条件下将水溶性蛋白质分子增溶进反胶团的极性核（水池）中，再创造条件将蛋白质抽提至另一水相，实现蛋白质的相转移，达到分离和提纯蛋白质的目的[1]．反胶团中的蛋白质分子受到周围水分子和表面活性剂极性头的保护，仍保持一定的活性，甚至表现出超活性[2]．由于蛋白质增溶于反胶团与蛋白质所带电荷及反胶团内表面电荷间的静电作用及反胶团的大小有关[3～5]，因而表面活性剂的种类、水溶液的PH值及离子强度等因素…     

C12-s-C12•2Br在正庚烷中反胶团形成及增溶水特性

在助表面活性剂正己醇存在下, 季铵盐Gemini表面活性剂C12-s-C12•2Br(s=2、3、4、5、6、8、12)在正庚烷中形成了反胶团. 以水增溶法测定了临界反胶团浓度cmcw, 这些cmcw均分别小于它们在水中生成正胶团的临界浓度cmcaq. cmcw随s的变化规律与cmcaq随s的变化规律类似, 在s=4时出现极大值. 由水增溶法和电导法获得的反胶团饱和增溶水量(mw或mc)约在s=5时出现最大值. 这些现象被归结为联接链构型的变化.     

C_(12)-s-C_(12)·2Br和C_(12)E_n混合水溶液的胶团化行为

季铵盐二聚表面活性剂C12-s-C12·2Br(s=2、3、4、6)和非离子表面活性剂C12E10或C12E23在水溶液中生成混合胶团.其临界胶团总浓度cmcT值介于二元复配体系中各组分的临界胶团浓度cmc01和cmc02之间.当添加少量非离子型表面活性剂(在水溶液中的摩尔分数α2=0.1)时,混合胶团中C12E10或C12E23的摩尔分数均已超过0.35;随着溶液中非离子型表面活性剂含量的增大,混合胶团中逐渐以C12E10或C12E23成分为主.     

C12-s-C12·2Br和C12En混合水溶液的胶团化行为

季铵盐二聚表面活性剂C12-s-C12@2Br(s=2、3、4、6)和非离子表面活性剂C12E10或C12E23在水溶液中生成混合胶团.其临界胶团总浓度cmcT值介于二元复配体系中各组分的临界胶团浓度和之间.当添加少量非离子型表面活性剂(在水溶液中的摩尔分数α2=0.1)时,混合胶团中C12E10或C12E23的摩尔分数均已超过0.35;随着溶液中非离子型表面活性剂含量的增大,混合胶团中逐渐以C12E10或C12E23成分为主.     

聚醚型表面活性剂水溶液中胶团的生成

属于ABA型嵌段共聚物(A为聚氧乙烯,B为聚氧丙烯)的聚醚型表面活性剂分子在水中是否生成胶团,文献报道的结果迥异,临界胶团浓度值随测定方法不同出入很大.某些AB型或ABA型嵌段共聚物在选择性有机溶剂中表现出异常胶团化行为,但对于水体系迄今未见报道.本文以多种实验手段研究了典型的聚醚型表面活性剂Pluronic L-64水溶液的胶体与表面性质.结果表明,与通常的表面活性剂不同,随着温度或浓度的变化,L-64溶液中生成单分子胶团或者缔合胶团.在两者的转变间,首次观察到了水体系中的异常胶团化现象.     

C9pPHCNa与C10TABr混合水溶液的表面吸附和胶团形成

羧酸盐Gemini表面活性剂C9pPHCNa与季铵盐表面活性剂十烷基三甲基溴化铵(C10TABr)混合水溶液的胶团生成能力、降低水表面张力的能力和效率均出现明显的增效.当C9pPHCNa在溶液中的摩尔分数(α1)为0.33时,cmcT(临界胶团总浓度)、γcmc(临界胶团总浓度对应的表面张力)、c20,T(降低20mN·m-1水表面张力所需的表面活性剂总浓度)这3个指标均达到最低值,分别为0.60mmo·lL-1、23.5mN·m-1和1.58×10-5mol·L-1.在所有考察的溶液比例范围内,二组分在混合胶团和表面吸附层中的组成均接近等摩尔比,表现出强烈的分子间相互作用.     

庚烷中C12-EOx-C12•2Br反胶团的形成

在助表面活性剂正己醇存在下, 季铵盐Gemini表面活性剂C12-EOx-C12•2Br(x=1, 2, 3)在正庚烷中形成了反胶团. 以碘光谱法测定了临界反胶团浓度(cmch), 该值小于它们在水中形成正胶团时的临界浓度(cmcaq), 但两者随x的变化规律一致, 均呈单调增长. 反胶团饱和增溶水量随x增加或温度升高而增大.     

Triton X-100/CTAB在乙二醇/水混合溶剂中的热力学性质和胶团化行为

利用表面张力法, 研究了非离子表面活性剂Triton X-100和离子表面活性剂十六烷基三甲基溴化铵(CTAB)混合体系在混合极性溶剂乙二醇/水(乙二醇的体积分数分别为5%、10%和20%)中的热力学性质和胶团化行为. 结果表明, 混合体系在乙二醇水溶液中存在协同效应, 临界胶束浓度随乙二醇含量的增加而增大. 利用Rubingh和Maeda模型计算了混合物中各组分在胶团相中的组成、相互作用参数以及自由能的贡献. 在实验研究的乙二醇浓度范围内, 发现该非离子/离子混合体系在离子组分摩尔分数约为0.3时, 协同效应最强.     

AEOT反胶束中脂肪酶的催化活性

反胶束已广泛应用于膜模拟化学和蛋白质的液 液萃取中[1～ 3] ,反胶束酶反应作为实现有机相酶催化的方法之一 ,具有许多独特的优点 ,反胶束独特的结构特征使表面活性剂分子组成的膜将油水相隔开 ,从而有利于保持酶的活性和稳定性。酶在反胶束的微水环境中比在水溶液中更接近天然的细胞内环境 ,在这里酶和底物分子均可得到有效的分散 ,接触几率大大提高 ,因而催化效率也得到很大提高。反胶束可以适用于各种类型的 (亲水的、疏水的和双亲的 )底物[4] ,已逐步形成“胶束酶学”的研究分支 ,研究胶束酶学的Martinek等[3] 曾预言 :反胶束体系有可…     

AEOT/异辛烷/水反胶束体系中合成导电聚苯胺

利用阴离子表面活性剂丁二酸二[2-(2-乙基己氧基)乙基]酯磺酸钠(AEOT)形成的反胶束为模板,制备出粒径小而均匀的导电聚苯胺.讨论了反应时间、反应温度、氧化剂与单体的摩尔比、酸浓度、表面活性剂用量及表面活性剂循环利用对聚合产物性能的影响.利用紫外-可见光谱、红外光谱、X射线衍射、Olympus显微镜及透射电镜对产物进行了表征.     

Reversed micellar solutions in the system sodium octanoate/decanol/water: Model calculations and dynamic light scattering measurements

Geometrical calculations of aggregate sizes in the reversed micellar solution phase of the system water/sodium octanoate/decanol at 20 °C have been tested by dynamic light scattering studies. The autocorrelation functions were interpreted in the simplest possible way (monodisperse aggregates, Stokes-Einstein diffusion equations) since the geometrical model does not account for detailed changes in shapes or micellar interactions. The model predicts the main features of micellization in these solutions, i. e., the micelles grow continuously as the concentration of water or the molar ratio water/octanoate increases, association begins at quite low concentrations of water and the surrounding decanolic solvent behaves as pure decanol which is saturated with water.     

Formation and Characterization of Reversed Micelles Composed of Phospholipids and Fatty Acids

The formation of reversed micellar systems composed of phosphatidylcholine (PC) and fatty acid was newly demonstrated by a significant increase in water content in the organic ethyl oleate phase when the micelles were prepared by the contact method. The solubilized water concentration in the reversed micellar organic phase reached 3 wt%. The new systems are expected to be used as highly biocompatible reversed micellar systems. The structure of the reversed micelles composed of PC and oleic acid was characterized by determining the water concentration and by small-angle X-ray scattering analysis. The reversed micelles composed of PC and oleic acid formed in ethyl oleate were spherical. The radius of gyration was between 30 and 50 Å. The size of the reversed micelles decreased with an increase in the oleic acid concentration and was independent of the PC concentration. Experimental results indicated that the structure of the reversed micellar system was determined by the oleic acid concentration. An increase in the PC concentration caused an increase in the number of reversed micelles of the same size. These reversed micellar systems are expected to be used as solubilization media in pharmaceutical and food industries because they are not toxic.     

Catalytic behavior of tris(2,2'-bipyridine)iron(II) complex in chemiluminescence reaction of luminol in reversed micellar medium of cetyltrimethylammonium chloride

Tris(2,2'-bipyridine) complex of iron(II) was found to cause an increase in the chemiluminescence (CL) emission of luminol dispersed in the reversed micellar medium of cetyltrimethylammonium chloride (CTAC) in 1:1 (v/v) dichloromethane-cyclohexane/water, when the iron(II) complex in dichloromethane was mixed directly with the reversed micellar solution containing luminol. Visible absorption measurements showed that, when dispersed in the CTAC reversed micellar medium, the iron(II) complex dissociates easily. In the reverse micelle, subsequently the free iron(II) ion produced may catalyze the CL oxidation of luminol even in the absence of hydrogen peroxide. The CL emission produced under the optimized experimental conditions was detectable at a minimum iron(II) concentration of 1.0 x 10(-9) M using a flow injection system.     

A review of: “Principles of Colloid and Surface Chemistry”. Paul C. Hiemanz. Marcel Dekker,Inc., New York and Basel, 1977. xi+516 pp.m $22.50

A general reaction model for styrene hydrogenation in the CTAB/l-hexanol(l-pentanol or l-butanol)/water reversed micellar solutions was proposed to interpret the catalytic behavior of monodisperse nickel boride particles prepared in situ. Based on this model, the effect of reversed micellar components on hydrogenation activity of the catalyst has been discussed in detail. It is worth noticing that, in the three reversed micellar systems, adding ethanol into the reversed micellar solutions will result in the change of catalyst's activity in the different ways, i.e. decrease for the reversed micellar solution with the low CTAB concentration (6 wt%) and increase for those with the high CTAB content (23 wt % or 38 wt%). The result is attributed to the combined     

Effect of hexanol on the reversed micelles of Span 85 modified with Cibacron Blue F-3GA for protein solubilization

Sorbitan trioleate (Span 85) modified with Cibacron Blue F-3GA (CB) was used as an affinity surfactant (CB-Span 85) to form affinity-based reversed micelles in n-hexane. It was found that the addition of hexanol to the reversed micellar system resulted in a significant increase in water content and hydrodynamic radius of the affinity-based reversed micelles. Moreover, the reversed micelles with hexanol revealed broader aggregation number distribution and larger average aggregation number than the reversed micelles without hexanol addition. This is considered to be due to the decreases in the micellar curvature and rigidity of the micellar interfacial layer and the increase in the micellar interfacial fluidity. Consequently, the solubilization capacity of lysozyme increased about 70% in the reversed micellar solution with 3 vol% hexanol. On the other hand, the capacity of BSA was only 30% increased under the same conditions due to its larger molecular size than lysozyme. Kinetic analysis revealed that the increase in the micellar interfacial fluidity in the presence of hexanol resulted in faster release of lysozyme from the micelles, thus leading to an increase of the overall volumetric mass transfer coefficient in the back extraction.     

Hexadecyltrimethylammonium bromide/ethanol/water systems as mobie phase in reverse phase high performance liquid chromatography. Study of metal-diethyldithiocarbamate complexes retention

Summary This paper presents the, chromatographic retention of Co(II), Ni(II) and Cu(II) as diethyldithiocarbamate complexes in the presence of hexadecyltrimethylammonium bromide/ethanol/water systems, as mobile phase, by reversed phase high performance liquid chromatography. The presence of an organic modifier reduces the retention times and improves the efficiency. In order to evaluate the interaction between the metal complexes and the mixed micellar system the values of solute binding constants are calculated in, two ways: a) Arunyanart and Cline-Love's treatment and b) multiple regression analysis taking account of the ethanol percentages.     

PHOTOCHEMICAL cis/trans ISOMERIZATION OF AN AMPHIPHILIC MEROCYANINE DYE IN HOMOGENEOUS SOLUTION AND REVERSED MICELLES

Abstract— In the present study, the photochemical cis⇌trans isomerization of the amphiphilic merocy-anine dye (4-hydroxy-l-cetyl stilbazolium betaine C₁₆M) is reported. The structure of each isomer is established from high resolution FT ¹H-NMR analysis. The photochemical quantum yields φ_t→c, and φ_c→t are determined in methanol and in reversed micelles of the system (CDBA, benzene, water). The quantum yield φ_c→t increases in reversed micelles compared to that in methanol. The reverse results are obtained for φ_t→c. The micellar effect on the photochemical trans→cis isomerization will be discussed.