荧光探针研究混合阴阳离子表面活性剂的有序组合体

对于羧酸钠-季铵盐正、负离子表面活性剂混合体系(I. C_9COONa-C_(10)NMBr及ⅡC_(11)C-OONa-C_8NMBr)的荧光探针研究揭示出: 表面活性剂胶团与囊泡形态的微极性相同, 但微粘度有显著差别(囊泡大于胶团). 体系Ⅰ在超声处理前后有不同的微粘度进一步说明胶团超声分散再自组合成囊泡的结果. 自时间分辨荧光光谱得出体系Ⅰ的较大胶团聚集数表明此混合胶团为长棒状.     

10-十一烯酸衍生物混合体系的表面化学

自表面张力测定对１０－十一烯酸胆碱衍生物（三甲基－［２－（１０－十一烯酰氧乙基）］碘化铵）与１０－十一烯酸钠混合体系的表面吸附和胶团形成作了研究；对该体系中的囊泡形成进行了电镜观察。结果表明，疏水链端基为不饱和烯基的正、负离子表面活性剂混合体系和有饱和疏水链的混合体系一样，也有很高的表面活性，易于表面吸附和形成胶团，并且容易在水及乙醇－水溶液中形成相当稳定的囊泡。这些结果的原因可归之于正、负表面活     

甲酰胺与正负离子表面活性剂有序溶液的研究

对羧酸钠与烷基三甲基溴化铵1：1混合体系的研究表明：常温下各体系在不同比例甲酰胺（FA）／水混合溶剂中，表面张力随浓度变化均有明显的转折点，显示了混合体系中胶团的存在．实验中发现随混合溶剂中FA比例增加，各体系的临界胶团浓度（cmc）增大．在较高温度下发现在甲酰胺中亦存在着因胶团形成而产生的表面张力-浓度对数（γ－logc）曲线的转折点，利用相分离模型对体系胶团热力学参数进行了计算．并探讨了FA对正负离子表面活性剂囊泡的影响．     

辛基三甲基溴化铵与辛基硫酸钠混合水溶液的相行为

对辛基三甲基溴化铵(OTAB)与辛基硫酸钠(SOS)正、负离子混合表面活性剂水溶液的相行为进行了研究.在高浓度的溶液中,混合表面活性剂形成液晶相,随着混合摩尔比OTAB/SOS接近于1,液晶结构由六角相转层状相,同时夹杂少量沉淀物;在中等浓度时,任意混合摩尔比例下皆为均相透明溶液;在低浓度下,在很宽的OTAB/SOS混合摩尔比的范围,出现双水相,其中的表面活性剂稀薄相,为不同大小的胶团与囊泡组成的稀溶液,另一表面活性剂富集相中则为数密度很大的囊泡聚集体,富集相对油溶性染料的增溶作用比非富集相高得多.     

烷基氯化铵体系中分子有序组合体的转化

采用动态光散射、吸收光谱、粘度及电镜透射等方法研究了烷基氯化铵在弱碱性条件下溶液浓度变化对分子有序组合体结构的影响.当表面活性剂浓度大于cmc时,分子有序组合体的形态随表面活性剂浓度的增加出现胶团-囊泡-球状胶团的转化过程,这与水解产生的极性有机物烷基胺量的变化密切相关.     

全氟辛酸与十二烷基硫酸钠混合溶液中的胶团形成

用表面张力法、电导法,pH测定法研究全氟辛酸-十二烷基硫酸钠混合水溶液的胶团形成及全氟辛酸胶团的特性.结果表明:(1)电导法与pH测定法弥补了表面张力法的不足,进一步证明在碳氟链表面活性剂与碳氢链表面活性剂混合水溶液中形成两种胶团.(2)全氟辛酸与十二烷基硫酸钠混合水溶液中所形成的两种胶团,分别基本上由全氟辛酸和十二烷基硫酸钠组成.十二烷基硫酸钠的存在对全氟辛酸胶团的形成不显示影响.全氟辛酸的氢离子对十二烷基硫酸钠胶团显示反离子效应.(3)全氟辛酸是典型的离子型表面活性剂,由于它对氢离子的结合力特别强,其胶团几乎是电中性的.这一特性可以解释全氟辛酸-十二皖基硫酸钠混合溶液胶团形成的机制.     

寡聚核苷酸/单链阳离子表面活性剂囊泡与沉淀共存(英文)

DNA(包括寡聚核苷酸)和阳离子表面活性剂可形成难溶复合物.本文通过浊度测试和透射电子显微镜观察,发现单链阳离子表面活性剂可以诱使寡聚核苷酸/单链阳离子表面活性剂沉淀转变成为寡聚核苷酸/单链阳离子表面活性剂囊泡,且寡聚核苷酸/单链阳离子表面活性剂囊泡可以与寡聚核苷酸/单链阳离子表面活性剂沉淀共存.在寡聚核苷酸/单链阳离子表面活性剂沉淀向囊泡的转变过程中,表面活性剂和沉淀之间的疏水作用力发挥了重要作用.此外,当体系温度达到寡聚核苷酸开始融解的温度后,寡聚核苷酸/单链阳离子表面活性剂体系更容易形成囊泡.因此,寡聚核苷酸的链越伸展,越易于寡聚核苷酸/单链阳离子表面活性剂囊泡的生成.据我们所知,有关寡聚核苷酸/阳离子表面活性剂囊泡的报道尚不多见.因此,考虑到DNA(包括寡聚核苷酸)/两亲分子体系在医学、生物学、药学和化学中的重要性,该研究应该有助于我们进一步了解该体系并对其进行更合理有效的应用.     

季铵盐表面活性剂与卵磷脂囊泡相互作用的研究

采用动态光散射、ζ电势等方法研究了季铵盐二聚表面活性剂(C₁₂-8-C₁₂•2Br)和十二烷基三甲基溴化铵(DTAB)在卵磷脂囊泡中的增溶作用. C₁₂-8-C₁₂•2Br使囊泡粒径增大, 促进脂双层向胶团的转变, 过程明显分为三个阶段; 而DTAB与囊泡的作用则相对缓和, 72 h内未见明显变化. 此外, 用亲水头基总体积的大小, 讨论了这两种表面活性剂在脂质体中的吸附行为, 并对实验现象加以解释说明.     

氧杂氟表面活性剂及其与同电性碳氢表面活性剂混合溶液的表面吸附和胶团形成

研究了四种氧杂氟表面活性剂及其与同电性直链碳氢表面活性剂混合体系的表面活性;考察了混合体系中的表面吸附和胶团形成现象.在吸附层中分子间有明显的互疏作用,在溶液中倾向于各自形成胶团.还讨论了反离子结合度不同对理想混合胶团的组成及cmc的计算的影响,提出了一般的计算式.实验测得这些氧杂氟表面活性剂有较低的胶团反离子结合度.     

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…     

Competitive adsorption of surfactants at air/water interfaces

The zeta potential of an air bubble suspended in an aqueous solution of mixed fluorocarbon and hydrocarbon anionic surfactants is studied over a wide range of concentrations and mixture compositions. The zeta potential is related to surfactant ion adsorption. The two surfactants, which exhibit an antipathy manifested by micellar demixing, compete for surface sites. The total surfactant adsorption is reduced when both surfactants are present. Adsorption phenomena are closely correlated to the micellar phase diagram.     

Vesicles of a new salt-free cat-anionic fluoro/hydrocarbon surfactant system

Weakly basic tetradecyldimethylaminoxide (C14DMAO) molecules can be protonated to form a cationic surfactant, C14DMAOH+, by an acidic fluorocarbon surfactant, an 8-2-fluorotelomer unsaturated acid (C7F15CF==CHCOOH), to form a salt-free cationic and anionic (cat-anionic) fluoro/hydrocarbon surfactant system in aqueous solution. The high Krafft point of C7F15CF==CHCOOH was largely reduced as a result of being mixed with a C14DMAO micelle solution. A study of the phase behavior of the new salt-free cat-anionic fluoro/hydrocarbon surfactant system clearly indicates the existence of a birefringent Lalpha-phase region at (25.0+/-0.1) degrees C. The birefringent Lalpha phase consists of vesicles, which include uni- and multilamellar vesicles with one to dozens of shells, and oligovesicular vesicles, as demonstrated by freeze-fracture and cryo-transmission electron microscopy (FF- and cryo-TEM) images. The size distribution and structural transitions in the salt-free cat-anionic fluoro/hydrocarbon surfactant system were studied by dynamic light scattering (DLS) and 1H and 19F NMR spectroscopy. The formation of a salt-free cat-anionic vesicle phase could be induced by the strong electrostatic interaction between the cationic hydrocarbon C14DMAOH+ and the anionic fluorocarbon C7F15CF==CHCOO-, which provided evidence that the electrostatic interaction between the cationic and anionic surfactants is larger than the nonsynergistic interaction between the stiff fluorocarbon and the soft hydrocarbon chains of the surfactants.     

Adsorption Properties of Hydrocarbon and Fluorocarbon Surfactants Ternary Mixture at the Water-Air Interface

Measurements were made of the surface tension of the aqueous solutions of p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethylene glycols) having 10 oxyethylene groups in the molecule (Triton X-100, TX100) and cetyltrimethylammonium bromide (CTAB) with Zonyl FSN-100 (FC6EO14, FC1) as well as with Zonyl FSO-100 (FC5EO10, FC2) ternary mixtures. The obtained results were compared to those provided by the Fainerman and Miller equation and to the values of the solution surface tension calculated, based on the contribution of a particular surfactant in the mixture to the reduction of water surface tension. The changes of the aqueous solution ternary surfactants mixture surface tension at the constant concentration of TX100 and CTAB mixture at which the water surface tension was reduced to 60 and 50 mN/m as a function of fluorocarbon surfactant concentration, were considered with regard to the composition of the mixed monolayer at the water-air interface. Next, this composition was applied for the calculation of the concentration of the particular surfactants in the monolayer using the Frumkin equation. On the other hand, the Gibbs surface excess concentration was determined only for the fluorocarbon surfactants. The tendency of the particular surfactants to adsorb at the water-air interface was discussed, based on the Gibbs standard free energy of adsorption which was determined using different methods. This energy was also deduced, based on the surfactant tail surface tension and tail-water interface tension.     

Characteristics of mixed bilayers of surfactants formed on alumina

The interaction between hydrocarbon and fluorocarbon surfactants on-alumina has been studied through the dispersion behavior of-alumina. When a low concentration of anionic hydrocarbon or fluorocarbon surfactant as a first additive is added to positively charged alumina, the alumina flocculates. The flocculated alumina redisperses upon addition of different surfactant from the first one by the manner that the hydrophobic parts of hydrocarbon and fluorocarbon surfactants are in contact with hydrophobic parts of the first surfactants and the hydrophilic polar groups direct out to liquid phase, resulting in the formation of mixed bilayers on the alumina. From the measurements of mean particle size, zeta potential of the alumina, and adsorbed amount of surfactants, the mixed bilayers consisting of anionic fluorocarbon-noniomc hydrocarbon surfactants and of anionic fluorocarbon-noioic hydrocarbon ones are found to be formed more preferentially than anionic hydrocarbon-anioic fluorocarbon surfactants. The property of the mixed bilayer on the alumina is also discussed using the fluorescence spectra of pyrene.     

Solubilization mechanism of vesicles by surfactants: effect of hydrophobicity

Simulations based on dissipative particle dynamics are performed to investigate the solubilization mechanism of vesicles by surfactants. Surfactants tend to partition themselves between vesicle and the bulk solution. It is found that only surfactants with suitable hydrophobicity are able to solubilize vesicles by forming small mixed micelles. Surfactants with inadequate hydrophobicity tend to stay in the bulk solution and only a few of them enter into the vesicle. Consequently, the vesicle structure remains intact for all surfactant concentrations studied. On the contrary, surfactants with excessive hydrophobicity are inclined to incorporate with the vesicle and thus the vesicle size continues to grow as the surfactant concentration increases. Instead of forming discrete mixed micelles, lipid and surfactant are associated into large aggregates taking the shapes of cylinders, donuts, bilayers, etc. For addition of surfactant with moderate hydrophobicity, perforated vesicles are observed before the formation of mixed micelles and thus the solubilization mechanism is more intricate than the well-known three-stage hypothesis. As the apparent critical micellar concentration (φ(s,v)(a,CMC)) is attained, pure surfactant micelles form and the vesicle deforms because the distribution of surfactant within the bilayer is no longer uniform. When the surfactant concentration reaches φ(s,v)(p), the vesicle perforates. The extent of perforation grows with increasing surfactant concentration. The solubilization process begins at φ(s,v) (sol), and lipids leave the vesicle and join surfactant micelles to form mixed micelles. Eventually, total collapse of the vesicle is observed. In general, one has φ(s,v)(a,CMC)≤φ(s,v)(p)≤φ(s,v)(sol).     

Prediction of conformational characteristics and micellar solution properties of fluorocarbon surfactants

A molecular-thermodynamic theory is developed to model the micellization of fluorocarbon surfactants in aqueous solutions, by combining a molecular model that evaluates the free energy of micellization of fluorocarbon surfactant micelles with a previously developed thermodynamic framework describing the free energy of the micellar solution. In the molecular model of micellization developed, a single-chain mean-field theory is combined with an appropriate rotational isomeric state model of fluorocarbon chains to describe the packing of the fluorocarbon surfactant tails inside the micelle core. Utilizing this single-chain mean-field theory, the packing free energies of fluorocarbon surfactants are evaluated and compared with those of their hydrocarbon analogues. We find that the greater rigidity of the fluorocarbon chain promotes its packing in micellar aggregates of low curvatures, such as bilayers. In addition, the mean-field approach is utilized to predict the average conformational characteristics (specifically, the bond order parameters) of fluorocarbon and hydrocarbon surfactant tails within the micelle core, and the predictions are found to agree well with the available experimental results. The electrostatic effects in fluorocarbon ionic surfactant micelles are modeled by allowing for counterion binding onto the charged micelle surface, which accounts explicitly for the effect of the counterion type on the micellar solution properties. In addition, a theoretical formulation is developed to evaluate the free energy of micellization and the size distribution of finite disklike micelles, which often form in the case of fluorocarbon surfactants. We find that, compared to their hydrocarbon analogues, fluorocarbon surfactants exhibit a greater tendency to form cylindrical or disklike micelles, as a result of their larger molecular volume as well as due to the greater conformational rigidity of the fluorocarbon tails. The molecular-thermodynamic theory developed is then applied to several ionic fluorocarbon surfactant-electrolyte systems, including perfluoroalkanoates and perfluorosulfonates with added LiCl or NH(4)Cl, and various micellar solution properties, including critical micelle concentrations (cmc's), optimal micelle shapes, and average micelle aggregation numbers, are predicted. The predicted micellar solution properties agree reasonably well with the available experimental results.     

Probing the impact of advanced melting and advanced adsorption phenomena on the accuracy of pore size distributions from cryoporometry and adsorption using NMR relaxometry and diffusometry

The penetration of compressed CO(2) in hydrocarbon and fluorocarbon regions of concentrated surfactant mesophases are interpreted from differences in the CO(2)-processed pore expansion of mesoporous silica thin films templated by three surfactants containing varying degrees of hydrocarbon and fluorocarbon functionality. Ordered silica thin films are synthesized for the first time using the 16-carbon (C(16)) partly fluorinated surfactant, 11,11,12,12,13,13,14,14,15,15,16,16,16-tridecafluorocetyl pyridinium bromide (HFCPB), as a templating agent. Silica films templated with surfactants containing a 8-carbon (C(8)) fluorocarbon tail (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl pyridinium chloride (HFOPC)) and a 16-carbon (C(16)) hydrocarbon tail (cetyl pyridinium bromide (CPB)) and HFCPB (C(16)) are processed in compressed CO(2) (69-172 bar, 25 °C and 45 °C) during synthesis. CO(2) processing results in significant pore expansion for films templated with both fluorinated surfactants, while pore expansion is negligible for the hydrocarbon templated material suggesting that preferential CO(2) penetration occurs in the 'CO(2)-philic' fluorocarbon segments of the surfactant template. The effect of substrate surface energy on the final uniformity of the dip-coated films is studied by varying the substrate from unmodified glass to a fluorocarbon-capped substrate. The ability to create dip-coated thin films on low surface energy substrates through favorable interaction of surfactant template tail with the substrate surface functional groups is demonstrated.     

Wettability of polymeric solids by ternary mixtures composed of hydrocarbon and fluorocarbon nonionic surfactants

Contact angle (θ) measurements on poly(tetrafluoroethylene) (PTFE) and polymethyl methacrylate (PMMA) surface were carried out for the systems containing ternary mixtures of surfactants composed of: p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycols), Triton X-100 (TX100), Triton X-165 (TX165) and Triton X-114 (TX114), and fluorocarbon surfactants, Zonyl FSN100 (FSN100) and Zonyl FSO100 (FSO100). The aqueous solutions of ternary surfactant mixtures were prepared by adding TX114, FSN100 or FSO100 to binary mixtures of TX100+TX165, where the synergistic effect in the reduction of the surface tension of water (γ(LV)) was determined. From the obtained contact angle values, the relationships between cosθ, the adhesion tension and surface tension of solutions, cosθ and the reciprocal of the surface tension were determined. On the basis of these relationships, the correlation between the critical surface tension of PTFE and PMMA wetting and the surface tension of these polymers as well as the work of adhesion of aqueous solutions of ternary surfactant mixtures to PTFE and PMMA surface were discussed. The critical surface tension of PTFE and PMMA wetting, γ(C), determined from the contact angle measurements of aqueous solutions of surfactants including FSN100 or FSO100 was also discussed in the light of the surface tension changes of PTFE and PMMA under the influence of film formation by fluorocarbon surfactants on the surface of these polymers. The γ(C) values of the studied polymeric solids were found to be different for the mixtures composed of hydrocarbon surfactants in comparison with those of hydrocarbon and fluorocarbon surfactants. In the solutions containing fluorocarbon surfactants, the γ(C) values were different taking into account the contact angle in the range of FSN100 and FSO100 concentration corresponding to their unsaturated monolayer at water-air interface or to that saturated.     

Promoting Efficacy and Environmental Safety of Pesticide Synergists via Non-Ionic Gemini Surfactants with Short Fluorocarbon Chains

Improving the utilization rate of pesticides is key to achieve a reduction and synergism, and adding appropriate surfactant to pesticide preparation is an effective way to improve pesticide utilization. Fluorinated surfactants have excellent surface activity, thermal and chemical stability, but long-chain linear perfluoroalkyl derivatives are highly toxic, obvious persistence and high bioaccumulation in the environment. Therefore, new strategies for designing fluorinated surfactants which combine excellent surface activity and environmental safety would be useful. In this study, four non-ionic gemini surfactants with short fluorocarbon chains were synthesized. The surface activities of the resulting surfactants were assessed on the basis of equilibrium surface tension, dynamic surface tension, and contact angle. Compared with their monomeric counterparts, the gemini surfactants had markedly lower critical micelle concentrations and higher diffusivities, as well as better wetting abilities. We selected a single-chain surfactant and a gemini surfactant with good surface activities as synergists for the glyphosate water agent. Both surfactants clearly improved the efficacy of the herbicide, but the gemini surfactant had a significantly greater effect than the single-chain surfactant. An acute toxicity test indicated that the gemini surfactant showed slight toxicity to rats.