NMR法研究胶束的增溶作用

本文用高分辨~1H.NMR谱研究了多种短链芳烃及其衍生物在阳离子表面活性剂—十六烷基三甲基溴化铵(CTAB)水溶液胶束和非离子表面活性剂—月桂基聚氧乙烯(4)醚(Brij30)非水溶液胶束中的增溶作用。得到这些不同种类的增溶物在两种不同类型的胶束中增溶位置的详细结果。并讨论了增溶物与表面活性剂分子之间的相互作用。这一研究对深入探讨增溶机理十分有益。     

Preparation and Unimolecular-Micellization Behavior of Homopolymer of Surface-Active Monomer AMC14AB

采用水溶液均聚合方法,制备了阳离子型表面活性单体(2-丙烯酰胺基)乙基十四烷基二甲基溴化铵(AMC14AB)的均聚物,使用荧光探针法、表面张力测定及电导测定法,重点考察了均聚物P(AMC14AB)在水溶液中的胶束化行为与表面吸附现象. 在水溶液中,均聚物P(AMC14AB)呈现单分子链胶束的聚集形态,具有零临界胶束浓度,从开始加入P(AMC14AB)起,水溶液中随即产生单分子链胶束,不存在Krafft温度. P(AMC14AB)在溶液表面也发生表面吸附,使水的表面张力下降,即P(AMC14AB)也具有表面活性;随着浓度增大,表面吸附量增大,水的表面张力持续下降;当表面吸附达饱和时,表面张力～浓度曲线上出现突变点,该点定义为饱和的表面吸附浓度,而不应该再称为临界胶束浓度. P(AMC14AB)单分子链胶束溶液对疏水有机物(甲苯)的增溶情况,明显不同于普通小分子表面活性剂十六烷基溴化铵(CTAB)的多分子胶束溶液,甲苯增溶量～P(AMC14AB)浓度的关系曲线上无突变点,而且对甲苯的增溶能力高于CTAB的多分子胶束溶液.     

PVP对三类胶束增溶苯甲醇的影响

选用碳链长度相同，极性基不同的三类表面活性剂：两性（Ｃ１２ＢＥ）阴离子（ＳＤＳ）阳离子（ＤＴＡＢ）形成胶束，通过高分辨核磁共振仪及分光光度计，研究了有或无高分子化合物ＰＶＰ（聚乙烯吡咯烷酮）时，三类胶束增溶苯甲醇的位置及增溶量，结果表明，ＰＶＰ包缠于ＳＤＳ胶束外围，并有部分高分子链嵌入胶束中，使胶束粒径扩大，不仅侃ＳＤＳ长链亚甲基裂分所需的增溶量增大，而且使ＳＤＳ胶束增溶苯甲醇的总量也增大，但是，     

Spectral Properties and Solubilization Location of 2'-Ethylhexyl 4-(N,N-Dimethylamino)benzoate in Micelles

在阳离子、非离子和阴离子表面活性剂胶束溶液中,研究了4-(N,N-二甲氨基)苯甲酸2'-乙基己基酯(EHDMAB)的双重荧光和紫外吸收．当EHDMAB增溶在不同的胶束溶液中,紫外吸收增强,在离子型胶束溶液中,可观察到具有较长波长的EHDMAB分子内扭转电荷转移(TICT)荧光,相反,在非离子型胶束溶液中,可观察到具有较短波长TICT荧光,特别是位于阳离子胶束Stern层中的吡啶阳离子可强烈猝灭EHDMAB分子的双重荧光,所吸收的紫外辐射主要通过TICT荧光和非辐射去活化衰减．按照EHDMAB分子TICT荧光在有机溶剂中的极性依赖性,EHDMAB分子的4-(N,N-二甲氨基)在离子型胶束和非离子型胶束中处于不同的极性环境;根据EHDMAB和表面活性剂分子的结构和大小分析,EHDMAB分子的4-(N,N-二甲氨基)应朝向胶束的极性头基团,而2'-乙基己基链则朝向疏水性的胶束内核．动态荧光猝灭测量为EHDMAB分子在不同胶束中的位置进一步提供了佐证．     

环境样品中痕量铝的现代光度分析研究新进展

论文综述和评论了近年来环境样品中痕量铝的光度分析研究新进展。重点论述了现代光度分析法测定环境样品中铝的研究新进展 ,内容包括 :胶束增溶分光光度法、双波长分光光度法、导数分光光度法、催化光度法、固相光度法、流动注射光度法。对普通光度法和胶束增溶光度法的反应体系、测定条件、摩尔吸收系数 (ε)或检出限、线性范围及其应用进行了归纳总结 ,评述了各种光度法测定的优劣 ,展望了光度法测定痕量铝的发展前景     

Effect of Short Chain Alcohols upon Viscosity of TTAB Solution

研究了不同条件下乙醇、丙醇和丁醇对十四烷基三甲基溴化铵(TTAB)溶液粘度行为的影响． 结果表明, 在无KBr存在下,TTAB溶液相对粘度随着醇的加入线性增加,说明醇分子没有增溶到TTAB胶束之中;在KBr存在下,TTAB溶液相对粘度随着乙醇的加入不断减小,但是会随着丙醇和丁醇的加入出现最大值,说明丙醇和丁醇的加入会促进TTAB胶束的增长;在KCl存在下,丙醇和丁醇的加入对TTAB胶束的影响几乎可以忽略不计．一种可能的解释是：KBr的存在促进了TTAB胶束的增长．因此,TTAB胶束内核的疏水程度有所增加,导致在特定浓度条件下丙醇和丁醇溶解到胶束中进一步促进了TTAB胶束的增长．     

水溶性聚合物与十二烷基硫酸钠相互作用的1H NMR研究

用¹H NMR方法研究了分别在2 g/L聚乙烯吡咯烷酮(PVP)和2 g/L聚乙烯醇（PVA）存在下，一系列不同浓度的十二烷基硫酸钠(SDS)溶液. 二维NOESY实验表明，SDS在浓度为2.5 mmol/L时形成胶束，且PVP被增溶到胶束内部；当SDS浓度低于2.5 mmol/L时，PVP与SDS之间没有明显的相互作用. 自旋-自旋弛豫时间的测量结果支持这一结论. 实验中没有检测到PVA与SDS之间的相互作用.     

双亲金属卟啉在SDS胶束中的光谱性质及动力学研究

5,10,15-3(4-羟基酚基)-20-(4-十六烷氧基酚基)卟啉锌(P1Zn)增溶于SDS胶束中,用敏感于微环境变化的紫外-可见光谱,研究了P1Zn在pH正向滴定和逆向滴定过程中Sorer带和Q带的变化与体相pH值的依赖关系。随着pH值由中性变化到强酸性,P1Zn中的锌原子被氢原子取代生成P1,而pH值由强酸性变化到中性,P1中的氢原子并未被锌原子取代生成P1Zn。在中性条件下P1与Zn(Ⅱ)的动力学表明,在pH值变化过程中,其增溶位置可能发生了变化,初步分析了双亲卟啉的结构对于增溶位置的影响。     

稳态荧光探针法测定Tween系列非离子表面活性剂临界胶束浓度

以芘为荧光探针,测定了不同条件下的Tween系列表面活性剂增溶芘后的稳态荧光光谱,建立了Tween非离子表面活性剂的临界胶束浓度(CMC)的测试方法,研究了影响非离子表面活性剂临界胶束浓度的因素。根据I338/I333与Tween浓度的变化关系,可得到Tween20、40、60、80的临界胶束浓度分别为5.1×10-5、3.7×10-5、3.1×10-5、8×10-6mol/L。结果表明,同系列的非离子表面活性剂的分子结构对其临界胶束浓度有一定影响。同时,制备温度和外部添加的试剂如无机盐、乙醇、丙三醇均影响其临界胶束浓度。     

AOT微乳体系中纳米银的可控合成及其紫外-可见光谱研究

在以琥珀酸二异辛酯磺酸钠(AOT)为表面活性剂、环己烷为连续相形成的W/O型微乳体系中,用增溶于微乳液水核中的AgNO₃为银源、水合肼为还原剂制备了纳米银溶胶,利用UV-Vis光谱分析了AgNO₃的浓度、AOT的浓度、还原剂的种类和水与表面活性剂的物质的量比(W)等参数对形成粒子数量及平均粒径的影响,为纳米银粒子的可控合成和纳米银的UV-Vis光谱解析提供了新的依据。研究表明,适当增大AgNO₃的浓度,有利于形成粒径较小的纳米银粒子;W值增大,形成粒子的平均粒径和粒子数量明显增加。和NaBH₄相比,水合肼在反胶束中的溶解性能较好,有利于微乳液反胶束中Ag+的还原。增大AOT的浓度,在一定范围内胶束对反应物的增溶能力增强,胶束的半径也相应减小,有利于形成数量较多、平均粒径较小的纳米银粒子。     

Immobilization of RuS2 Nanoparticles Prepared in Reverse Micellar System onto Thiol-Modified Polystyrene Particles and their Photocatalytic Properties

RuS₂ nanoparticles, smaller than 3 nm in diameter, were prepared by H₂S gas injection into the AOT/isooctane reverse micellar solution containing RuCl₃ aqueous solution. The nanoparticle size was found to be independent of the W_o (water content) value of the reverse micellar system, as shown by TEM observation. The recovery and immobilization of the RuS₂ nanoparticles from reverse micelles onto thiol-modified polystyrene particles (PSt-SH) were successfully carried out, by the addition of PSt-SH into the reverse micellar solution under conditions of mild stirring. The resulting composites, PSt-RuS₂, showed photocatalytic activity for H₂ generation form aqueous solution containing 2-propanol and Na₂SO₃ as sacrificial electron donors.     

A laser flash photolysis study of the dynamic behaviour of radical pairs in micellar solutions under ultrahigh magnetic fields of up to 30 T

The photo-induced hydrogen abstraction reactions of benzophenone in aqueous micellar SDS and Brij 35 solutions, decafluorobenzophenone in an aqueous micellar Brij 35 solution and naphthoquinone in an aqueous micellar SDS solution were investigated at room temperature under pulsed magnetic fields of 0–29.6T. In each of these reactions, the radical pair decay rate is found to decrease with increasing field from 0 to about 3 T and to increase with increasing field above 3 T. The escape radical yield is found to increase with increasing field from 0 to about 3 T and to decrease with increasing field above 3 T. These magnetic field effects are explained in terms of the relaxation mechanism. In each of the Brij 35 micellar solution systems, the anisotropy in the g tensor of the ketyl radical and its correlation time are evaluated from the observed effects.     

Mixed micellar aggregates of nonionic surfactants with short hydrophobic tails

Mixed micelle formation by aqueous mixtures of pentaethylene glycol monohexyl ether (C₆E₅) and diethylene glycol monohexyl ether (C₆E₂) has been investigated by determining the temperature-composition phase diagrams and measuring the intradiffusion coefficients. In binary aqueous solutions, C₆E₅ shows a high tendency to micellize, while C₆E₂, because of its too short hydrophilic head, presents a macroscopic phase separation in a water-rich and a surfactant-rich phases. The temperature-composition phase diagrams obtained for the ternary water-C₆E₅---C₆E₂ mixtures present a micellar region in which both surfactants co-aggregate. The dimensions of this micellar region depend on the relative ratio between the two surfactants molalities. By analysing the micelle intradiffusion coefficient, measured through the PGSE-NMR technique, the hydrodynamic radius of the aggregates has been estimated at 25 °C. It is similar to that of triethylene glycol monohexyl ether (C₆E₃) in binary aqueous solution. The experimental evidences suggest that in mixed ethoxylated surfactants the micellar behaviour is mainly determined by the mean number of ethoxylic units per surfactant molecule, independently of their distribution.     

Effects of alkyl chain lengths of gallates upon their distribution and reactivity towards diphenylpicryl hydracil radicals in Triton X‐100 micellar solutions

The reactivity of ethyl‐, propyl‐ and octylgallate towards diphenylpicryl hydracil radicals has been measured in homogeneous solution (ethanol) and in Triton X‐100 micellar solutions. Similar reactivities were measured in homogeneous solutions, indicating that the length of the alkyl chain does not influence the reactivity of the phenolic groups. On the other hand, different reactivities were measured in micellar solutions, particularly at low (5 mM) surfactant concentrations. Data obtained at different surfactant concentrations allow estimation of partitioning of the gallates and their intramicellar bimolecular rate constant. The values obtained indicate that all the observed differences in reactivity are attributable to differences in substrate partitioning between the micellar and aqueous pseudophases. In fact, similar values of the intramicellar rate constants were obtained, suggesting that the average location of the reactive groups inside the micelles is independent of the solute alkyl chain length. Copyright © 2009 John Wiley & Sons, Ltd.     

Electrodeposition of cobalt with tunable morphology from reverse micellar solution

Electrodeposition of cobalt on a copper electrode was successfully performed from aqueous and reverse micellar solutions of a cationic surfactant, cetyltrimethylammonium bromide (CTAB), using constant potential electrolysis method. The potential to be applied for electrodeposition was judged from the cyclic voltammetric behavior of cobalt(II) in aqueous and reverse micellar solutions of CTAB at different compositions. The morphology, dimension, and crystallinity of cobalt deposited onto a copper substrate were evaluated from scanning electron microscopy (SEM) images and X-ray diffraction technique. The cobalt deposited on copper from aqueous solution does not show any definite shape and size, while the deposition from reverse micellar solutions occurred with definite shapes such as star-, flower-, and nanorod-like structures depending on the composition. The slow kinetics governed by the reverse micelles associated with the deposition brings about oriented growth of cobalt onto the copper substrate and offers the potential to electrochemically tune cobalt deposit with desirable morphology.     

SDS胶束溶液在石油类污染物荧光光谱测量中的应用

提出了一种以十二烷基硫酸钠(SDS)胶束溶液为溶剂增溶、增敏、增稳石油类物质的新方法。研究了石油类物质的荧光强度随SDS胶束溶液浓度的变化规律,确定了其溶剂SDS胶束溶液的最佳浓度为0.1 mol·L-1。使用FLS920荧光光谱仪测量得到不同稀释浓度的汽油、柴油、煤油SDS胶束溶液的三维荧光光谱矩阵(EEMs),分析了瑞利(Rayleigh)散射、拉曼(Raman)散射以及仪器光谱特性对测量光谱的影响,经过光谱校正,建立了三种油的SDS胶束溶液在激发波长为250～400 nm、发射波长为260～500 nm范围内的三维荧光光谱图,并确定了在一定浓度范围内荧光强度与浓度具有良好的线性关系。在相同条件下,用同样的方法配制各种浓度汽油、柴油、煤油水溶液作对比,验证了SDS胶束溶液作为石油类物质的溶剂可以使水中石油类物质的溶解度增加、荧光强度增大、稳定性更好,实现了石油类物质可以不依赖于某些有毒溶剂萃取,又解决了其水中溶解度低不宜定量的问题。     

表面活性剂及水溶性功能高分子的NMR研究

核磁共振（NMR）技术是研究表面活性剂在溶液中聚集状态的一种非常有用的工具,本文运用多种NMR技术研究了几种不同类型表面活性剂及水溶性功能高分子在水溶液中的聚集行为： 1. 季铵盐型双子表面活性剂16-4-16的聚集行为季铵盐型双子表面活性剂N,N′-双(十六烷基二甲基)-α,ω-丁烷溴化铵(16-4-16)分子中联接基团及靠近离子头的质子位于胶束的壳层, 运动受到一定限制. 而距离离子头较远的烷烃链位于胶束的内部,运动相对自由. 与对应的单链表面活性剂十六烷基三甲基溴化铵(CTAB)相比,16-4-16形成的胶束堆积更为紧密. 通过NOESY谱中交叉峰强度的定量计算,认为16-4-16在胶束中分子以上下交错排列的方式形成球形聚集体.  2. 脱氧胆酸钠与十六烷基三甲基溴化铵的相互作用在脱氧胆酸钠(NaDC)溶液中,NaDC质子H3与其他质子不同,其横向弛豫时间(T₂)表现为双指数衰减,表明此质子可能存在两种不同的状态. 实验证明,其它胆酸盐的H3的横向弛豫也呈现双指数衰减. 因此推测在胆酸盐的稀溶液中,3-OH质子和羰基氧之间有可能存在氢键作用,形成了头尾相连的分子对结构.  在NaDC和CTAB的混合溶液中,两者形成1∶1的混合胶束. 用NOESY和ROESY研究混合胶束的结构,显示CTAB的离子头位于NaDC的羧酸基团附近. 这可能是正负离子之间的静电性相互作用的结果.  3. 丙烯酰胺/丙烯酸模板共聚物的微结构研究了不同pH值条件下,丙烯酰胺和丙烯酸共聚物分子在水溶液中的聚集形态. 在酸性溶液中,分子内的氢键致使聚集体形成较为紧密的堆积,侧链的苯氧基团运动受阻;随着溶液pH值的增大,丙烯酸电离产生的阴离子使得分子间的静电斥力增大,分子链变得伸展,分子间的氢键作用导致了聚集体体积变大. 当溶液呈强碱性,丙烯酸完全电离,氢键作用力被破坏,分子呈现自由伸展的状态,侧链的苯氧基团运动相对自由.     

Small angle neutron scattering study on the aggregation behaviour of PEO-PPO-PEO copolymers in the presence of a hydrophobic diol

Small angle neutron scattering (SANS) measurements on aqueous solutions of four polyethylene oxide-polypropylene oxide-polyethylene oxide block copolymers (commercially known as Pluronic®)F88, P85, F127 and P123 in the presence of hydrophobic C14Diol (also known as Surfynol® 104) reveal information on micellization, micellar size and micellar transitions. While most hydrophilic F88 (with least PPO/PEO ratio) remained unimers in water at 30°C, other copolymers formed micellar solutions. Surfynol® 104 is sparingly soluble in water to only about ～0.1 wt%, but on addition to pluronic solution, it gets incorporated in the micellar region of block copolymer which leads to increase in aggregation number and transformation of spherical to ellipsoidal micelles. The added diol-induced micellization in F88, though hydrophilic copolymers F88 and F127 did not show any appreciable micellar growth or shape changes as observed for P85 and P123 (which are comparatively more hydrophobic). The SANS results on copolymer pairs with same molecular weight PPO but different % PEO (viz. F88 and P85, F127 and P123) and with same molecular weight PEO but different PPO (F88 and F127) reveal that the copolymer with large PPO/PEO ratio facilitate micellar transition in the presence of diol. An increase in temperature and presence of added electrolyte (sodium chloride) in the solution further enhances these effects. The micellar parameters for these systems were found out using available software and are reported.     

FT-EPR study of photoionization in micellar solutions

Fourier Transform EPR (FT-EPR) was used to study the formation and decay of free radicals produced by photoionization of phenothiazine (PTH) solubilized in aqueous SDS and Triton X-100 micellar solutions in the absence and presence of electron acceptors. CIDEP spectra produced by PTH photoionization in micellar solution differ from those found in homogeneous solution. The effect is attributed to changes in relative importance of single-photon, singlet excited state, and biphotonic, triplet excited state, photoionization. With quinone acceptors present in the bulk aqueous phase, photoionization of PTH in SDS, results in instantaneous formation of quinone anion radicals that carry the spin polarization of the precursor hydrated electrons. If the acceptor is anchored in the micelle, electron capture cannot compete with electron escape into the aqueous phase. Instead, anion radicals are formed primarily by reductive quenching of³PTH*. This process gives rise to a spectrum that is attributed to long-lived spin-correlated radical pairs, [PTH⁺…Q^?].