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.     

醇对高效氯氟氰菊酯微乳液相图的影响

通过电导率的测定研究了高效氯氟氰菊酯微乳液的结构结构及结构转变。在表面活性剂、高效氯氟氰菊酯环己酮溶液、醇相对含量一定的情况下,当醇为乙醇时,微乳液经历了由W/O到双连续最后到O/W型的变化;当醇为正辛醇时,微乳液经历了由W/O到液晶、双连续最后到O/W型的变化。绘制了不同条件下高效氯氟氰菊酯微乳体系的拟三元相图,讨论了醇种类、醇含量对各类型微乳区形成的影响。结果表明,随着醇碳链的增大,微乳区面积先增大后减小;醇(正辛醇)固定时,随着醇含量增加,微乳区面积先减小后增大。     

介观模拟研究水包油型微乳液的形成及稳定性

采用耗散颗粒动力学模拟方法从介观尺度上研究了水包油(O/W)型微乳液的形成条件并对所形成的O/W型微乳液的耐环境(油水体积比、温度、盐度和剪切作用)稳定性进行分析。结果表明,油水体积比小于1:3时,油水界面张力最小,可以形成O/W型微乳液。此微乳液具有一定的耐低温稳定性,其耐温稳定性范围为0.8 kBT~1.0 kBT。在此温度范围内,1.0 kBT时的微乳液具有最好的耐盐性,αHH降低为22时微乳液才发生相转变。此外,剪切作用对不同条件下所形成的微乳液具有一定破坏作用,当温度为1.0 kBT、αHH为25时,剪切速率增加到0.009,微乳液才受到破坏,也就是说,此条件下的微乳液是稳定的。此模拟结果从介观尺度上提供了微乳液的结构变化,为微乳液的实际应用提供理论指导。     

蒽在SDS/BA/H2O体系中的光谱特征

用紫外-可见吸收光谱和荧光发射光谱研究了蒽在不同组成和结构的十二烷基硫酸钠(SDS)/苯甲醇(BA)/H20微乳液中的光谱特征,探讨了微乳液组成和结构对蒽光谱特征的影响,阐述了蒽在微乳液中的定位。结果表明,蒽位于O/W微乳液的膜相和油核;在SDS/BA/H2O W/O微乳液中,蒽定位于油连续相。     

CTAB/正丁醇-正辛烷-水和盐水的拟三元体系相图及微乳液微观结构的电导研究

绘制了CTAB/正丁醇-正辛烷-水和Al(NO₃)3(或Na2WO4)盐水拟三元体系的35℃相图.用电导法并结合电解质理论讨论了微乳液的微观结构,将整个微乳液单相区分为W/O微乳区、O/W微乳区和B.C.双连续区,并且用渗滤理论确定了一个分散相质点为W/O球状结构的反胶团微乳液区.     

辐射冷冻乳液聚合制备多孔聚合物微球

本文研究了常规苯乙烯乳液和苯乙烯细乳液在两种不同冷冻条件下,即液氮冷冻和-20℃冰箱冷冻过程中乳液体系稳定性的变化,以及γ射线辐射引发冷冻乳液中单体聚合得到的聚苯乙烯微球的形貌,并探讨了形貌形成机制.结果表明,乳液在-20℃冰箱中冷冻过程中乳液稳定性破坏,单体出现分层现象.而液氮冷冻可以保持冷冻前的乳液相态结构.γ射线辐射可以引发冻乳液中苯乙烯聚合,聚合过程中体系经历了从O/W乳液向W/O/W多重乳液的转变,最终形成粒径分布较宽,直径为1~20μm的泡孔状多孔PS微球.本工作不仅为低温聚合技术提供了新思路,也为多孔聚合物微球材料的制备提供了新方法.     

β-胡萝卜素微乳液的制备及其稳定性研究

通过绘制拟三元相图选择合适的微乳液组分,制备了β-胡萝卜素的Tween80/乙醇/丁酸乙酯/H2O的O/W型微乳液。考察了温度、盐度和pH对微乳液区域的影响:电导率法区分了微乳液的O/W、W/O和B.C(油-水双连续型)区域;对相同浓度β-胡萝卜素的微乳液和丁酸乙酯溶液进行了光、热稳定性研究,用紫外分光光度法测定样品中β-胡萝卜素的残存率。结果表明,温度升高和pH降低使微乳区稍有减小,盐度对微乳区基本无影响;微乳体系中水的质量分数大于61·5%时形成O/W型微乳液;β-胡萝卜素在微乳液和丁酸乙酯溶液中对光和热都比较敏感,但在微乳液中较稳定。     

DEA与SDS/n-C5H11OH/H2O微乳液的相互作用

以循环伏安法研究了N,N-二乙基苯胺（DEA）与十二烷基硫酸钠（SDS）/正戊醇（n-C5H11OH）/H2O体系O/W和W/O结构微乳液的相互作用.结果表明,DEA在SDS/n-C5H11OH/H2O体系微乳液中有两种定位方式:其一,DEA分子在微乳液液滴膜相中定位于表面活性剂和助表面活性剂的极性基团附近;其二,DEA分子在微乳液液滴膜相中定位于表面活性剂疏水基团一侧.两种定位的分布与微乳液的结构和组成相关.     

不同因素对高效氯氟氰菊酯微乳液相图的影响

通过电导率的测定研究了高效氯氟氰菊酯微乳液的结构及结构转变, 绘制了不同条件下高效氯氟氰菊酯微乳体系的拟三元相图, 讨论了十二烷基苯磺酸钠(SDBS)摩尔分数、电解质浓度、温度等因素对各类型微乳区形成的影响. 结果表明: ①随着SDBS摩尔分数增大, W/O型微乳区面积先减小后增大, BC和O/W型面积先增大后减小; ②随着电解质浓度增大, W/O、BC和O/W型微乳区面积均先增大后减小; ③随着温度升高, W/O型微乳区面积增大, BC和O/W型面积均减小.     

青霉素G钾盐在CTAB/n-C5H11OH/H2O体系中的水解及 其抑制

应用紫外光谱法研究了青霉素G钾盐在十六烷基三甲基溴化铵(CTAB)/n-C5H11OH/H2OO/W微乳液中的水解反应。结果表明,CTAB/n-C5H11OH/H2OO/W微乳液对青毒素G钾盐的水解具有抑制作用,此结果与此O/W微乳液能降低青霉素G钾盐(Pen-K)分子极性基团的电荷密度,减少Pen-K所处微环境的质子浓度有关。     

2,4-二硝基氯苯在微乳液中的水解动力学

十六烷基三甲基溴化铵;正辛烷;正丁醇;2;4-二硝基氯苯在微乳液中的水解动力学     

Effect of the structures of microemulsions on chemical reactions

Two kinds of chemical reactions were studied in two different microemulsion systems: cetyltrimethylammonium bromide/1-butanol/10 and 25% n-octane/water and sodium dodecyl sulfonate/1-butanol/20% styrene/water. One reaction is a hydrolysis reaction, in which aspirin and 2,4-dinitrochlorobenzene were used as the hydrolysis substrates. The second reaction is the polymerization of styrene, which was initiated by using two initiators, water-soluble K₂S₂O₈ and oil-soluble 2,2′-azobis(isobutyronitrile), and, at the same time, the polymerization of acrylamide, which was initiated by NaHSO₃, was also studied. All the hydrolysis reaction experimental results show that the hydrolysis is greatly affected by the structures and the structural transitions of microemulsions. The hydrolysis rates are higher in water-in-oil (W/O) microemulsion media and decrease with the addition of water. The rates increase in bicontinuous (BC) microemulsions and decrease in oil-in-water (O/W) microemulsions. The transition points of the hydrolysis rates occurred at the two microemulsion structural transition points from W/O to BC and from BC to O/W. The polymerization relationships between the conversions of styrene, the molecular weights of polystyrene and the water contents of the microemulsion system were obtained. The effects of microemulsion structures on the sizes of the polystyrene particles and on the molecular weights of the polymers are discussed. Polystyrene particles with diameters of 10–60 nm were observed by microscopy. Our experimental polymerization results show that microemulsions are suitable as media for the production of polymers, the molecular weights and the particle sizes of which can be controlled and predicted by variations in microemulsion structures. Received: 11 July 1999/Accepted: 26 July 1999     

Hydrolysis of Cephanone in SDS/n-C_5H_(11)OH/H_2O System

IntroductionMicellesolutioncomposedofsurfactantscanaffect,adjustandcontrolmanychemicalreactionsaccordingtoitseffectsoflocalconcentration ,polarity ,charge ,microvis cosity,electrostatics ,etc ..1,2 Recently ,ithasarousedmuchattentiontoconductchemicalreactionsusingmi croemulsionasmicroreactor .3 7Theeffectofmicelleonthechemicalreactionstemsfromitsstaticelectricityandhy drophobicity .Usually ,cationicsurfactantcancatalyzethereactionbetweennucleophileandneutralmolecule ,whileanionicsurfactantsusp…     

维生素C对表面活性剂体系相行为的影响

维生素Ｃ（ＶＣ）能提高表面活性剂十六烷基三甲基溴化铵（ＣＴＡＢ）在水中的溶解度,具有助溶作用;且能提高ｎ－Ｃ５Ｈ１１ＯＨ在Ｏ／Ｗ微乳液中的增溶量和水在Ｗ／Ｏ微乳液中的增溶量,Ｏ／Ｗ与Ｗ／Ｏ微乳液区域同时扩大,具有助溶－增溶作用。ＶＣ的助溶作用与助溶－增溶作用均具有一定的选择性,只对阳离子表面活性剂ＣＴＡＢ体系有效,ＶＣ助溶－增溶作用的机理是同时增加Ｗ／Ｏ和Ｏ／Ｗ微乳液的稳定性和层状液晶向双连续结构     

Hydrotrope and Hydrotrope-Solubilization Action of Urea in CTAB/n-C5H11OH/H2O System

Urea is found to show the hydrotrope action when the aqueous solubility of surfactant CTAB is enhanced while it will show the hydrotrope-solubilization action when the solubilized amount of n-C₅H₁₁OH in O/W microemulsion and that of water in W/O microemulsion are increased. The mechanism of the hydrotrope-sotubilization action of urea is in fact the increase of the stability of W/O and O/W microemulsion and structural transition from the lamellar liquid crystal phase to the bicontinuous structure.     

An Investigation of Structure Transition in Sodium Dodecyl Trioxyethylene Sulfate／n-Butanol／n-Octane／Water System by Dielectric Relaxation Spectroscopy Method

IntroductionDielectricrelaxationspectroscopy(DRS) possess esanimportantpositioninmodern physicochemicalanalysis .Dielectricmeasurementscanbedoneinsuchawidefrequencyrangeof 10 - 5— 10 11Hz ,makingitpossibletodetectallkindsofprocessesofvarioussys tems[1] .DRSisbasedonthepolarizationtheory ,in cludingdipolereorientation polarization ,interfacialpolarization ,ionicpolarizationandelectronicpolariza tion ,ofwhichinterfacialpolarizationis prevalent.Whenthereexistsaclearphaseinterface ,aninterfa c…     

Hydrotrope‐Solubilization Action of Urea in CTAB/n‐C5H11‐OH/H2O System

Urea can enhance the aqueous solubility of surfactant CTAB (hexadecyltrimethylammonium bromide) when it shows the hydrotrope action. It will show the hydrotrope‐solubilization action when the solubilized amount of n‐C₅H₁₁OH in O/W microemulsion and that of water in W/O microemulsion are increased. The mechanism of the hydrotrope‐solubilization action of urea is the increase of the stability of W/O and O/W microemulsion and structural transition from the lamellar liquid crystalline phase to the bicontinuous structure.     

Microemulsion polymerization of acrylamide and styrene: Effect of the structures of reaction media

Isothermal phase diagrams of the system cetyltrimethylammonium bromide (CTAB)/n‐butanol/n‐octane/water were constructed, and the effect of the oil (n‐octane) contents on the microemulsions was studied at 40 °C. We determined the microemulsion structures of two systems, CTAB/n‐butanol/10% n‐octane/water and sodium dodecyl sulfonate (As)/n‐butanol/20% styrene/water, by conductivity measurements to investigate the polymerization of acrylamide and styrene in the two microemulsion systems. The polymerization kinetics of the water‐soluble monomer acrylamide in CTAB micelles and the different CTAB/n‐butanol/10% n‐octane/water microemulsion media [water‐in‐oil (W/O), bicontinuous (BC), and oil‐in‐water (O/W)] were studied with water‐soluble sodium bisulfite as the initiator. The maximum polymerization rate in CTAB micelles was found at the second critical micelle concentration. A mechanism of polyacrylamide formation and growth was proposed. A connection between the structures of the microemulsions and the polymerization rates was observed; the maximum polymerization rate occurred at two transition points, from W/O to BC and from BC to O/W, and the polyacrylamide molecular weights, which depended on the structures of the microemulsions, were also found. A square‐root dependence of the polymerization rates on the initiator concentrations was obtained in CTAB micelles and O/W microemulsion media. The polymerization of the oil‐soluble monomer styrene in different As/n‐butanol/20% styrene/water microemulsion media (W/O, BC, and O/W) was also investigated with different initiators: water‐soluble potassium persulfate and oil‐soluble azobisisobutyronitrile. A similar connection between the structures of the microemulsions and the conversions of styrene in CTAB/n‐butanol/10% n‐octane/water for the polymerization of acrylamide was observed again. The structures of the microemulsions had an important role in the molecular weights and sizes of polystyrene. The polystyrene particles were 10–20 nm in diameter in BC microemulsion media and 30–60 nm in diameter in O/W microemulsion media according to transmission electron microscopy. We determined the solubilization site of styrene in O/W microemulsion drops by ¹H NMR spectra to analyze the results of the microemulsion polymerization of styrene. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3320–3334, 2001     

The Inhibition of the Hydrolysis of Cephanone by CTAB/n‐C5H11OH/H2O Microemulsion

Abstract

The hydrolysis of cephanone in water, cetyl trimethyl ammonium bromide (CTAB) micelle, and CTAB/n‐C₅H₁₁OH/H₂O O/W microemulsion was studied through UV‐VIS absorption spectroscopy. The mechanism of the hydrolysis and the effects of both the acidity of the media and the composition of O/W microemulsion on the hydrolysis were studied. The results show that the hydrolysis rate of cephanone increases with the acidity. Compared with water, CTAB micelle and CTAB/n‐C₅H₁₁OH/H₂O O/W microemulsion suppress this hydrolysis. The inhibition of the hydrolysis of cephanone by CTAB micelle and CTAB/n‐C₅H₁₁OH/H₂O O/W microemulsion is related to the location of cephanone in the interphases of CTAB micelles and CTAB/n‐C₅H₁₁OH/H₂O O/W microemulsion droplets.