W／O型微乳液活化能和导电机理研究

电导行为是微乳液的重要性质之一。自Lagourette和Lagues发现了W/O型微乳液电导渗透(Percolation)现象后,人们开始了微乳液导电机理的研究。较流行的观点认为,界面层中表面活性剂分子的阴离子在微乳颗粒碰撞时发生跃迁而使W/O型微乳液具有导电性。     

萃取有机相中微乳液的稳定性研究

赊P507钾盐外，PSO7理、钠、按盐和P204的理、钠、钾、按以及有机接盐等与醇一油一水在一定条件下都能形成微乳液．因此，进一步搞清这些体系形成微乳液的结构、性质和稳定性，对革取化学研究是十分重要的．我们曾对PSO7（K）一醇一正庚烷一水四组分体系的结构参数［’j和物理化学性质［’］进行过研究，观察到辅助表面活性剂性质和含水量对微乳液结构有重要的影响·本文采用测定微乳液电导的变化，研究含有不同醇和不同量水时，P507（K）在革取有机相中形成微乳液颗粒的活化能（凸E），并用凸E的大小来描述和比较微乳液的界面膜强度…     

油酸钠微乳液体系的结构参数和电导行为研究

本文用稀释法测定了油酸钠/醇/正庚烷/水四组分W/O型微乳液体系的结构参数:水内核半径Rw,颗粒有效半径Re,界面层厚度L,平均聚集数N,颗粒总数Nd,分散相总界面积Ad等结构参数和醇从连续相转移到界面的自由能△Goc-i。结果表明微乳液水内核半径Rw大小在纳米尺度;随含水量的增加,水内核半径Rw直线增加,而醇转移的界面自由能-△Goc-i减小,在含水量较低时微乳液的稳定性较强。对助表面活性剂的种类、内水相盐度变化对油酸钠微乳液电导率的影响进行了考察,结果表明使用正丁醇时形成电导渗滤体系,而使用正戊醇、异戊醇和正己醇时形成的是非渗滤体系;内水相中加入Na NO3对电导渗滤有抑制作用。醇碳链长度增加及适当的盐度有利于微乳液体系的稳定。     

阴离子型微乳液的电导行为及其溶液结构

根据电导测量,研究了属于W/O→双连续→O/W一类微乳液的十二烷基硫酸钠(SDS)/正丁醇/辛烷/水体系的溶液结构.并探讨了表面活性剂离子对微乳液导电行为的贡献,以及表面活性剂与助表面活性剂含量、油含量对微乳液溶液结构的影响.微乳液的导电行为在W/O子区域中主要是由于SDS阴离子和在O/W子区域中是由于Na离子的影响.在双连续区(IZ)中SDS阴离子和Na阳离子都能影响导电行为增加表面活性剂含量有助于形成O/W微乳液,而助表面活性剂和油含量都增加有助于于形成W/O微乳液.     

pH和盐类对非离子型表面活性剂所组成微乳液的异常流变性影响

以非离子型表面活性剂AEO~9、正十六烷、正己醇和水所组成的微乳液为对象, 研究盐和pH值对其粘度和流变性的影响, 得出它们在pH值为7时最小, 以及二价盐影响最大的结论, 正好与离子型微乳液结果相反, 为此进行了讨论。并从热效应和电导对其微观结构作了初步探索。     

微乳液结构的研究

测定了十二烷基磺酸钠／正丁醇／２０％苯乙烯／水体系的相平衡，用冷冻刻蚀、ＥＳＲ、ＦＴ－ＩＲ研究了上述体系微乳液的结构，研究表明，苯乙烯含量恒定时，随着体系中水含量增加，电导确定的双连续结构的微乳液经历着从油包水到以连续再到水包油变化，ＦＴ－ＩＲ测定表明，Ｗ／Ｏ微乳兴较Ｏ／Ｗ微乳液的ＯＨ伸缩振动和弯曲振动频率有显著减小，说明Ｗ／Ｏ微乳兴中氢键缔合要比Ｏ／Ｗ强得多。ＥＳＲ测定表明Ｏ／Ｗ微乳液的旋转相关     

影响反相微乳液导电性能的因素

分别以聚乙二醇辛基苯基醚(Triton X-100)或十六烷基三甲基溴化铵(CTAB)为表面活性剂, 与正己烷、正己醇和水构成反相微乳液. 研究了水相H+浓度、表面活性剂、助表面活性剂等对微乳液导电性能的影响. 结果表明, 增加水相H+浓度可大幅度提高反相微乳液的导电能力, 当H+浓度由1.0 mol•L-1增加到10 mol•L-1时, 微乳液的电导率可提高1~2个数量级. 当水相H+浓度为10 mol•L-1时, 微乳液的电导率随溶水量的增大而增大, 水油体积比为3:10时, 两种体系的电导率均达到3200 μS•cm-1. Triton X-100浓度对微乳液的电导率影响较大, 电导率随其浓度增加而增大；而CTAB浓度对微乳液电导率的影响较小, 电导率随其浓度增加略有减小；助表面活性剂正己醇使非离子型反相微乳液的电导率下降, 而使阳离子型反相微乳液的电导率先增大, 然后减小, 呈骆峰状变化.     

十二烷基硫酸钠微乳色谱体系中pH值对其电渗流行为与微结构的影响

以十二烷基硫酸钠(SDS)/正己烷/正丁醇/硼砂微乳液为毛细管电色谱运行研究体系,以甲醇峰为微乳体系电渗流峰(EOF),考察不同pH值条件下微乳体系电渗流出峰时间(tEOF)和变化趋势.以微乳液滴粒径和ξ电位考察pH值对SDS缓冲溶液微乳体系微结构的影响,用微乳体系的电导值分析pH值条件下微乳液滴与氢氧根离子之间的相互...     

电解质对非离子型微乳液的影响

本文通过测定微乳液的电导率和相图,研究了电解质(硝酸镍)对非离子型微乳液Triton X-100/正己醇/环己烷/水或硝酸镍水溶液系统稳定性的影响.发现分散相为水的微乳液体系中,表面活性剂的含量越大微乳液的电导率越大;分散相为盐溶液的微乳液体系中,微乳液的电导率随着盐溶液浓度的增大而减小;而且盐溶液浓度越大微乳液的含水量越小.     

有机硅微乳液的研究进展

近年来大量研究表明,有机硅微乳液与有机硅乳液相比,具有许多优异的性能,如优异的热稳定性、渗透性等。本文主要阐述了有机硅微乳液的形成原理、制备方法及制备过程中的影响因素。在有机硅微乳液的形成原理里,详细介绍了增溶理论和界面张力理论;在有机硅微乳液的制备中,着重讨论了表面活性剂、助表面活性剂、催化剂等对有机硅微乳液形成的影响。     

Ionic conductivity of pure water in charged porous matrix

It is commonly recognized that the ionic conductivity of pure water is very poor because of very low ionic concentrations. However, this work indicates that pure water in charged porous matrixes can be moderately conductive because of the ions in the electric double layer established at the solid/water interfaces. The ionic conductivity of pure water in a charged matrix changes with the electrode potential of the matrix and is influenced by the structural parameters. Both experimental measurements and theoretical calculations reveal that ionic conductivity may reach the order of 10(-3) S cm(-1) in commonly accessible potential region in a porous matrix made of gold nanoparticles. These results would help to understand and optimize the electrode processes in electrochemical devices without deliberately added electrolytes, such as polymer electrolyte membrane fuel cells.     

Dielectric relaxation measurements on aerosol-OT/water/cyclohexane-solutions at low water content

The complex relative dieletric permittivity of aerosol-OT(AOT)/water/cyclohexane solutions has been measured within the frequency range 5 kHz-10 GHz. The investigated solutions were of oil-rich type with varying AOT- and water content. A marked dielectric relaxation has been found. The dielectric increment as well as the conductivity steeply increase with the water content, while the relaxation time decreases. Theoretical models of heterogeneous dielectrics consisting of polar, highly conductive inclusions in a nonpolar solvent with low conductivity have been applied to the results, allowing conclusions with regard to the inclusions, shape and conductivity.     

Electrical charging of a conducting water droplet in a dielectric fluid on the electrode surface

It has been conceived that a charged droplet driven by Coulombic force can be used as a droplet-based microreactor. As a basic research for such applications, electrical charging of a conducting water droplet is studied experimentally. The effects of electric field, medium viscosity, and droplet size are investigated. It is found that the amount of electrical charging increases with the droplet size and the electric field. However, the medium viscosity does not have a significant effect in the range of the present study. A scaling law is derived from the experimental results. Unlike the case of a perfect conductor, the estimated amount of electrical charge (Q(est)) of a water droplet is proportional to the 1.59 power of the droplet radius (R) and the 1.33 power of the electric field strength (E). (For a spherical perfect conductor, Q is proportional to R(2) and E.) In order to understand these differences, numerical simulations are performed for the idealized droplets of perfect conductor. Comparison of the numerical and experimental results suggests that the differences are mainly due to incomplete charging of a water droplet resulted from the combined effect of electrochemical reaction at electrode and the relatively low conductivity of water.     

P(VDF-co-TrFE-co-CTFE)-g-SPS共聚物的合成表征

采用商业聚(偏氟乙烯-co-三氟氯乙烯)(P(VDF-co-CTFE)为原料,结合氢化反应、ATRP和磺化反应系统合成了一系列聚(偏氟乙烯-co-三氟乙烯-co-三氟氯乙烯)-g-磺化聚苯乙烯(P(VDF-co-TrFE-co-CTFE)-g-SPS)共聚物.重点研究了测试环境(如温度和相对湿度)、聚合物微观结构(接枝密度,接枝长度等)对聚合物形貌、吸水率和质子传导率的影响.研究表明,在接枝量相同的情况下,随着接枝密度的降低,聚合物的相分离更加明显,亲水相从孤岛型逐渐转变为部分连续型;聚合物的吸水率随磺酸基摩尔含量增加而提高;聚合物的质子传导率随着温度的提高和湿度的降低而降低;在较低温度下,聚合物的电导率随接枝密度的增加而降低,而在较高温度下,聚合物的电导率随接枝密度的增加而升高.组成优化的P(VDF-co-TrFE-co-CTFE)-g-SPS共聚物在30～120℃和高湿度条件下,其质子传导率明显优于Nafion112膜.     

The effect of obstacle conductivity and electric field on effective mobility and dispersion in electrophoretic transport: a volume averaging approach

The method of volume averaging has been used to determine the effective electrophoretic mobility and dispersion coefficients for molecular transport of point-like solutes in a two-phase porous medium where the electrical conductivity and the diffusion and mobility coefficients may vary in both phases. The formal theory, derived in previous work, is numerically evaluated for cases where the obstacle phase has a large or small conductivity relative to the fluid phase and where the diffusion coefficient of the solute in the obstacle phase can be large or small relative to that in the fluid phase. In agreement with previous Monte Carlo methods, the effective electrophoretic mobility is not a function of media conductivity or electric field when the obstacles are impermeable to solute transport or have small diffusion solute diffusion coefficients. However, the dispersion coefficient is a strong function of electric field and varies with obstacle conductivity when diffusive transport is small in the obstacles relative to the fluid. In contrast, the effective electrophoretic mobility is a function of electric field when conductivity of the obstacles is much larger than the fluid and when the obstacles are very permeable to solute but have low electrical conductivity.     

Micellization of Cetylpyridinium Chloride Using Conductometric Technique

Abstract

Conductometric technique has been used to investigate the equilibrium properties of cetylpyridinium chloride (CPC) in the presence of a series of aliphatic alcohols. The dependence of conductivity of surfactant solution in the presence of particular amount of alcohol has been studied. According to the experimental results, ethanol cause to decrease the dielectric constant and conductivity of micellar solution. Alcohols with longer chain may change the conductivity of solution depend on concentration of surfactant. At low concentration of CPC near critical micelle concentration (cmc) region, the minimum value of conductivity can be observed. This minimum value can be controiled by decreasing of free monomer concentration and also increasing degree of dissociation of micelle because of penetration of alcohols in micellar core. Using Conductometric technique cmc and α (degree of dissociation of counterion) of CPC were evaluated. The micelle formation of CPC has been considered in ethylene glycol (E.G)/ water and glycerol/water mixtures. It has been shown, the logarithm of cmc is directly depended on the ratio of E.G/water or glycerol/water.     

Superfast electrophoresis of electron-type conducting particles

The features of concentration polarization caused by electric current through a unipolar conductive particle are considered. The peculiarities of the formation of an induced space charge near a particle with electron-type conductivity are analysed. It has been shown that the theoretical values of electrophoretic velocity for these particles are essentially smaller than those calculated for particles with ion-type conductivity.A new method to observe the superfast electrophoresis is developed. The electrophoretic velocity of graphite and activated carbon particles of different size (diameter, 200–500 μm) displaced in distilled water and electrolyte solutions in strong electric fields (100–500 V cm⁻¹) was measured. It is shown that, in contrast to classical electrophoresis, the electrophoretic mobility of such particles increases with the particle size and the external field strength. The experimental and theoretical results are compared. The discrepancy between theory and experiment is analysed.     

An Improved Method for Calculating Zeta-Potentials from Measurements of the Electrokinetic Sonic Amplitude

The surface electric properties of the commercially available silica, Monospher 1000 (Fa. Merck), have been studied by conductivity and ESA (electrokinetic sonic amplitude) experiments. It could be shown that accounting for the contribution of the stagnant layer to surface conductivity is indispensable in the interpretation of electrokinetic data at low ionic strength. A general method has been put forward which allows to take into account the total, experimentally accessible surface conductivity in the evaluation of ESA data of moderately concentrated suspensions. This includes additional conductivity measurements which serve for the independent estimation of the total relative surface conductivity. The resulting zeta-potentials are clearly higher than those obtained after neglecting the contribution of the stagnant layer to surface conductivity. In addition, the ionic mobilities of potassium and magnesium in the hydrodynamically stagnant layer have been investigated in some detail. It has been found that the ionic mobility of potassium is of the same order of magnitude as in the bulk solution while the mobility of magnesium is significantly reduced. Copyright 2000 Academic Press.     

Effect of polyaniline on the stability of electrotransport characteristics and thermochemical properties of sulfocationite membranes with different polymer matrices

A comparative analysis of the electrotransport and thermochemical properties of homogeneous and heterogeneous sulfocationite membranes modified with polyaniline has been performed. The relationship between the conditions of polyaniline synthesis in the membrane matrix and their electric conductivity, electroosmotic permeability, and thermal stability was studied. The conditions of polyaniline synthesis on the surface of a heterogeneous MK-40 membrane had an insignificant effect on the amount of the introduced modifier, while the electric conductivity of the composites remained high enough. The absence of the effect of the polyaniline synthesis conditions on the electric conductivity of МK-40-based composites suggests that the heterogeneity of this membrane is a more significant factor than the polyaniline synthesis conditions. A thermogravimetric analysis of the thermochemical properties showed a significant increase in the thermal stability of the heterogeneous membrane after its modification with polyaniline. For perfluorinated membranes, the thermochemical properties changed less significantly, but the electrotransport of ions and water significantly decreased after modification.     

锂离子电池新型快充负极材料Li4Ti5O12的改性研究

采用传统固相法制备尖晶石型Li4Ti5O12, 在前驱物中掺杂聚合物裂解碳材料聚并苯(PAS). 经四探针测试仪测量, 电导率提高9个数量级. 复合物的电化学性能测试结果表明, 其循环性和高倍率性能得到了明显改善.