TX-100反相微乳液的缔合结构研究

对ＴＸ－１００、正戊醇、正己醇、正庚醇、正辛醇及辛烷形成的反相微乳液用ＥＳＲ自旋标记方法进行了研究，结果认为反相微乳液的形成过程伴随着表面活性剂链排列的变化，在加入水量较少时栅状区域的表面活性剂链排列拥挤，进一步的水化作用使其排列疏松。而疏水性强的探针则表明水化作用渗透到了反相微乳液的疏水区域。     

正负离子表面活性剂反胶团与反相微乳研究

研究了以癸烷为油相的十一烯酸癸胺正负离子表面活性剂体系对水的加溶作用。结果表明此体系在一定组成范围内可以形成均匀透明的反胶团或反相微乳液。升高温度和添加酸、碱、盐可以使形成反胶团或反相微乳的组成范围扩大。在正负离子表面活性剂中加入离子型表面活性剂、特别是负离子型表面活性剂,也有类似的作用。     

羧甲基纤维素系列高分子表面活性剂形成微乳液的研究

采用紫外光谱、相图、动态激光光散射、同位素示踪、光学显微镜、电导率等研究了羧甲基纤维素系列高分子表面活性剂与甲苯-水-异丙醇体系微乳液的形成过程,发现微乳液粒子大小均一,形态一致,其尺寸比低分子表面活性剂所形成的微乳液粒子大得多.醇分子插入到油水界面,改变了两相界面结构,促使微乳液的生成.电导率测定表明所形成的微乳液区均为水包油结构,即使在富含甲苯区域,亦不会有油包水的反相胶束形成.     

不同反离子对高效氯氰菊酯微乳液影响的研究

研究了结合不同反离子的十二烷基苯磺酸盐(DBS)与苯乙烯苯酚聚氧乙烯醚(NR600)形成的高效氯氰菊酯微乳液的导电机理, 以及反离子对体系相行为的影响. 研究结果表明, 由于阴离子表面活性剂的溶解度不同以及溶解后反离子结合度的差异, 使得反离子能改变微乳液界面的亲水亲油作用. 具有较小水化半径的K^＋使界面的亲水作用增强, 更有利于O/W型微乳液的形成, 而水化半径较大的Na^＋, Li^＋不如K^＋有利于O/W型微乳液的形成; Ca^2＋与表面活性剂的阴离子结合形成的油溶性的表面活性剂, 有利于微乳液界面亲油作用的增强, 不利于O/W型微乳液的形成. 这与热贮分解率的结果相一致.     

碳氢表面活性剂在超临界CO_2中形成微乳液的研究进展

在超临界CO2中形成微乳液可以克服CO2对高分子量和亲水性物质溶解能力差的缺点。碳氢表面活性剂成本低,对环境友好,利用碳氢表面活性剂形成超临界CO2微乳液有利于工业应用,但绝大部分碳氢表面活性剂不能形成微乳液,所以需要对碳氢表面活性剂进行选择和设计。本文介绍了微乳液的形成、表征和评价,从表面活性剂的亲CO2性能和界面活性两方面,综述了碳氢表面活性剂的设计思路和进展。另外介绍了助表面活性剂对形成超临界CO2微乳液的作用,并对常规碳氢表面活性剂在助表面活性剂的作用下形成超临界CO2微乳液的体系进行了综述。最后,介绍了含碳氢表面活性剂的混合表面活性剂在形成超临界CO2微乳液方面的研究情况。     

4-十二烷氧基苄胺在纳米金微粒合成中的应用

以新型表面活性剂4-十二烷氧基苄胺(C12OBA)构成的C12OBA/正丁醇/正庚烷/丙醛/HAuCl4(aq)反相微乳液作为微反应器,利用微波辐射加热-丙醛还原法制备了C12OBA包覆金纳米微粒;利用透射电镜、傅立叶变换红外光谱仪及X射线衍射仪分析了产物的微观形貌、化学键合特征、晶体结构;并测定了其紫外-可见吸收光谱.结果显示,表面活性剂C12OBA既可参与形成稳定的反相微乳液,又可作为金纳米微粒的良好保护剂.反相微乳液液滴的微小水核以及C12OBA/金的物质的量之比对纳米金微粒的尺寸和形貌起到良好的控制作用.     

介观模拟研究表面活性剂分支结构对W/O型微乳液的影响

本文采用耗散颗粒动力学模拟方法从介观水平上研究了表面活性剂分支结构对W/O型微乳液形成的影响。结果表明:对于不同链分支结构的表面活性剂/油/水体系在一定的油水比和表面活性剂浓度下可以形成W/O型微乳液,此时体系的平均界面张力值最低。但在表面活性剂浓度相同时,随着油水比的增加,直链表面活性剂H2T2最利于其形成;而在油水比相同条件下,随着表面活性剂浓度的增加,直链表面活性剂H2T2在较大浓度范围内依然为稳定的微乳液。也就是说直链表面活性剂最利于W/O型微乳液的形成。此模拟结果从介观水平上提供了表面活性剂分支结构对W/O型微乳液形成的影响,为微乳液的实际应用提供理论指导。     

表面活性剂分支结构对O/W型微乳液影响的介观模拟研究

采用耗散颗粒动力学模拟方法从介观水平上研究了表面活性剂分支结构对O/W型微乳液形成的影响。研究结果表明:对于不同链分支结构的表面活性剂/油/水体系在一定的油水比和表面活性剂浓度下可以形成O/W型微乳液,此时体系的平均界面张力值最低。当表面活性剂浓度相同时,随着油水比的降低,直链表面活性剂H2T2最利于O/W型微乳液的形成;而在油水比相同时,随着表面活性剂浓度的增加,直链表面活性剂H2T2在较大浓度范围内依然为稳定的微乳液。也就是说直链表面活性剂最利于O/W型微乳液的形成。此模拟结果从介观水平上提供了表面活性剂分支结构对O/W型微乳液形成的影响,为微乳液的实际应用提供理论指导。     

聚乙二醇在Triton X-114/正辛烷/正丁醇/水反相微乳液中的增 溶研究

研究了加入聚合物对TritonX-114/正辛烷/正丁醇/水组分体系相态的影响。利用次甲基蓝(MB)作为吸附探针,而以恶唑烷氮氧自由基(5-doxylstearicacid,5-DNS)作为自旋探针,研究了加入聚合物对TX-114/正辛烷/正丁醇/水反相微乳液的微结构影响。结果表明:聚合添加使W/O微乳液区缩小,而液晶区则更靠近水一端(增溶更多水)。该反相微乳液中存在三种状态水:结合水、束缚水、体相水。加入聚合物可以替代先前存在于TX-114聚氧乙烯链上的一些水分子,使其微极性减小,而且使表面活性剂分子在界面上的排列更为松散,本研究结果对探讨聚合物对W/O微乳液微结构的影响及此类体系在其它方面应用有重要意义。     

碳氢表面活性剂在超临界CO2中形成微乳液的研究进展

在超临界CO₂中形成微乳液可以克服CO₂对高分子量和亲水性物质溶解能力差的缺点。碳氢表面活性剂成本低,对环境友好,利用碳氢表面活性剂形成超临界CO₂微乳液有利于工业应用,但绝大部分碳氢表面活性剂不能形成微乳液,所以需要对碳氢表面活性剂进行选择和设计。本文介绍了微乳液的形成、表征和评价,从表面活性剂的亲CO₂性能和界面活性两方面,综述了碳氢表面活性剂的设计思想和进展。另外介绍了助表面活性剂对形成超临界CO₂微乳液的作用,并对常规碳氢表面活性剂在助表面活性剂的作用下形成超临界CO₂微乳液的体系进行了综述。最后,介绍了含碳氢表面活性剂的混合表面活性剂在形成超临界CO₂微乳液方面的研究情况。     

TX-100反相微乳液的红外光谱及电子顺磁共振研究

TX-100反相微乳液的红外光谱及电子顺磁共振研究     

The influence of structure and composition of a reverse SDS microemulsion on enzymatic activities and electrical conductivities

The activity of the enzyme horse radish peroxidase (HRP) is studied in a series of reverse microemulsions composed of dodecane, aqueous buffer, sodium dodecylsufate (SDS) and alcohols of the homologous series 1-butanol to 1-octanol. The HRP catalyzed reaction is the oxidation of a classical water soluble substrate, the 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) by hydrogen peroxide. In parallel electrical conductivity measurements are performed on the same solutions. The structural changes in the microemulsions, as inferred by the conductivity measurements, correlate remarkably well with the changes in the enzymatic activities. In particular it is found that (a) the maximum activity of the enzyme is always related to its optimum hydration and that this hydration can be related to the microemulsion structures, (b) the enzyme inhibition caused by the alcohols in microemulsions is a consequence of both the solubility of the alcohols in the buffer and the rigidity of the interfacial film. Consequently, it can be concluded that enzymatic activity measurements are a valuable tool to study confined systems such as microemulsions and, in particular, the amount of available hydration water. Enzymatic activities can be finely tuned by small changes in microemulsion structures, probably in a predictive way.     

微乳液聚合耦合共混法构建聚偏氟乙烯共混杂化膜

以苯乙烯和甲基丙烯酸甲酯混合物作为油相, 采用反相微乳液法制备了AgCl纳米粒子; 通过微乳液原位聚合油相单体得到包含AgCl纳米粒子的聚合乳液; 将聚合乳液与聚偏氟乙烯(PVDF)通过共混法构建了包含AgCl纳米粒子的PVDF共混杂化膜. 紫外-可见光谱、 透射电子显微镜(TEM)及扫描电子显微镜(SEM)等表征结果和超滤实验结果表明, 聚合乳液加入的同时引入了亲水性聚合物和表面亲水的AgCl纳米粒子, 不仅改善了PVDF共混杂化膜的孔隙率和平均孔径, 还显著增强了PVDF共混杂化膜的极性和亲水性, 最终提升了膜的水通量和抗污染性能; 过量聚合乳液加入后不能与PVDF材料均匀共混, 而且AgCl纳米粒子也会在膜中形成团聚物堵塞膜孔隙, 从而削弱了膜的水通量和抗污染性能.     

A fluorescence ratiometric nano-pH sensor based on dual-fluorophore-doped silica nanoparticles

We have synthesized dual-fluorophore-doped core-shell silica nanoparticles used as ratiometric pH sensor. The nanoparticles were prepared with a reverse microemulsion technique by simultaneously encapsulating two different fluorophores, the pH-sensitive dye fluorescein as a pH indicator and the pH-insensitive dye phenosafranine as an internal reference for fluorescence ratiometric measurement, into silica shell. The nanoparticles prevent the fluorescence dyes leaching from the silica matrix when immersed inside water. The hydrophilic silica shells were made by hydrolysing and polymerizing tetraethoxysilane (TEOS) in water-in-oil microemulsion. The fluorescence intensity ratio of the two dyes varied linearly as a function of pH in the range from 4.0 to 8.0. The sensor was also applied to measure pH of real water samples. The results are in good agreements with that using the conventional glass electrode method. The as-prepared fluorescent nanoparticles showed rapid response, excellent stability and high reproducibility as pH sensors.     

Self-assembly in linker-modified microemulsions

Linker molecules are added to microemulsion systems to enhance the interaction between the surfactant and oil (lipophilic linkers) or water (hydrophilic linkers) phases. Previous results suggest that when lipophilic and hydrophilic linkers are combined they behave as a self-assembled surfactant at the oil/water interface. In this work we investigate this self-assembly phenomenon as a function of surfactant, linker and electrolyte concentration. We find that middle phase microemulsion appears at a specific concentration higher than the critical micelle concentration (CMC), which we denote as the critical middle phase microemulsion concentration (CmicroC). When the lipophilic linker dodecanol is added in equimolar ratio to the hydrophilic linker sodium mono- and dimethyl naphthalene sulfonate (SMDNS), the middle phase microemulsion did not appear until the surfactant sodium dihexyl sulfosuccinate (SDHS) concentration was larger than the CmicroC of the SDHS-alone system. Dodecanol is shown to segregate near the surfactant tails following a Langmuir-type adsorption process. This segregation is not affected by the electrolyte concentration but is significantly reduced when the surfactant (SDHS) concentration approaches the CmicroC. The data suggest that the self-assembly between hydrophilic and lipophilic linkers to form middle phase microemulsions is only possible if a minimum amount of surfactant is present.     

Rapid and Efficient Formation of Reverse Vesicle on Carbon Fibers

Reverse vesicles are the counterparts of normal vesicles which are the aggregations of molecular bilayers with hydrophilic parts inside and hydrophobic parts outside. As their potential applications in many fields, they have attracted much attention of scientists. In this paper, we demonstrated a novel method to prepare reverse vesicles by through egg phosphatidylcholine (EggPC) membrane and microemulsion solution. Reverse vesicles of EggPC can be constructed quickly on carbon fibers. The formation of vesicles can be easily observed in situ under achromatic objective lens by an inverted optical microscope. It is very convenient to characterize the formation of reverse vesicles. We investigated the influences of curvature, adsorption effect, and hydrogen bond interaction on the formation of reverse vesicles and presented the mechanism.     

Efficient topical delivery of chlorogenic acid by an oil-in-water microemulsion to protect skin against UV-induced damage

We examined the intradermal delivery of a hydrophilic polyphenol chlorogenic acid by in vitro study using excised guinea pig dorsal skin and Yucatan micropig skin. Skin accumulation as well as the solubility of chlorogenic acid in aqueous vehicles was much greater than for other polyphenols such as quercetin and genistein. However, since enhancement of skin delivery seemed to be necessary to exhibit its protective effects against oxidative damage of skin, we examined the effects of microemulsions as vehicles. Using microemulsions consisting of 150 mM NaCl solution, isopropyl myristate, polyoxyethylene sorbitan monooleate (Tween 80) and ethanol, skin accumulation as well as solubility of chlorogenic acid further increased. Enhancement effect of an oil-in-water (o/w-type) microemulsion was greater than that of a water-in-oil (w/o-type) microemulsion possibly due to the greater increase in solubility. This finding was quite different from previous findings on relatively hydrophobic polyphenols such as quercetin and genistein. Pretreatment of guinea pig dorsal skin with chlorogenic acid containing microemulsion gel prevented erythema formation induced by UV irradiation. These findings indicate the potential use of hydrophilic chlorogenic acid with o/w-type microemulsion as a vehicle to protect skin against UV-induced oxidative damage.     

形成微乳状液的萃取有机相结构的福里埃红外光谱研究——环烷酸钠皂-仲辛醇-煤油-水体系

用福里埃变换红外光谱(FT-IR)法研究了钠皂环烷酸体系的加水过程,观察到了环烷酸阴离子的水化效应,水合配位发生在皂化的环烷酸阴离子的羧基和部分未皂化环烷酸分子的羰基上。钠皂环烷酸微乳状液同时发生阳离子和阴离子的水化效应,巨大水化能的释放可能是微乳状液作为一种热力学稳定体系的实验证据。     

反相微乳液中苯酚硝化反应选择性的研究

采用气相色谱内标法研究了苯酚在AOT/异辛烷/水、CTAB/正癸醇/异辛烷/水、DBSA/异辛烷/水3种反相微乳液中进行硝化反应的选择性;考察了表面活性剂种类、反应时间、反应温度以及反相微乳液的含水量等因素对反应选择性的影响.研究结果表明,苯酚在微乳液体系中的硝化反应具有明显的邻位选择性,阴离子表面活性剂DB-SA体系的邻位选择性最高,这与它同时具有微乳催化和酸催化作用有关.