SDS/BA/H~2O体系的结构与电学特性

SDS/BA/H~2O体系电导率、反离子缔合度和电容测定表明：在O/W微乳液区域,电导率、反离子缔合度和电容值都较小;在恒定m(SDS)/m(H~2O)下,随着BA含量的增加,电导率、反离子缔合度和电容值先增加,达到一最大值后又逐渐下降。在双连续区域,为链式导电机理,电导率、反离子缔合度、电阻和电容值几乎不随水含量变化。根据加权最小二乘法回归,O/W球形胶束区域的电容值与各物理化学特性数值(κ,β,N,D,ε,χ)的关系为：C/μF=1.036×10^-^8(1-β)Z~sκD^-^1+0.03466ε~1x~1=0.09677ε~2x~2。     

SDS/n-C5H11OH/H2O溶致液晶中SDS分子的扩散特性

以铂微电极法测定了在SDS/n-C5H11OH/H2O溶致液晶中SDS（十二烷基硫酸钠）分子的扩散系数.结果表明,恒定质量比SDS/n-C5H11OH条件下,溶致液晶中SDS分子的扩散系数随体系中水含量的增加而增加；恒定质量比SDS/H2O,溶致液晶中SDS分子的扩散系数随正戊醇含量的增加而增加；恒定质量比H2O/n-C5H11OH ,溶致液晶中SDS分子的扩散系数随SDS含量的增加而降低.六角状液晶中SDS分子的扩散系数比层状液晶中SDS分子的扩散系数低约1个数量级,而比W/O、O/W胶束的扩散系数低3～5个数量级.     

W/O/W多重乳液中水传递的控制

建立了简化的W/O/W(水/油/水)多重乳液乳珠模型——统计平均半径模型, 预测出当W/O/W多重乳液内水相水滴之间以及内外水相之间均达到水传递平衡时的内外水相中盐的浓度, 从而实现对水传递的控制, 以维持W/O/W多重乳液的稳定. 按理论预测制备出了不同稳定态的W/O/W多重乳液, 利用差分扫描量热仪(DSC)检测了多重乳液中水的传递过程, 确定体系在实验状态下的稳定程度, 实验结果与理论预测基本吻合.     

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。     

W/O微乳液中纳米Pd微粒的化学破乳沉积

利用脂肪醇聚氧乙烯醚型非离子表面活性剂Marlipal O13/50、水、环己烷组成的W/O微乳液体系合成纳米Pd微粒, 考察了化学破乳剂作用下纳米Pd微粒的沉积过程. 结果表明, 不同化学破乳剂使纳米Pd微粒沉积的速率顺序为1,4-二噁烷跃四氢呋喃跃甲醇跃乙醇跃正丁醇. 研究了化学破乳剂对微乳液界面张力与两亲因子的影响. 结果表明, 微乳液结构的破坏是界面张力增大的过程, 同时也是两亲性降低而向Lifschitz线逐渐靠近的过程.     

碱和盐对十二烷基硫酸钠/正戊醇-环己烷-水拟三元体系相图影响

拟三元相图的研究可为获得制备纳米材料的微乳液提供理论依据。本文首先通过实验绘制了45℃下十二烷基硫酸钠(SDS)/正戊醇-环己烷-水溶液体系的拟三元相图,并用电导法进行了验证,说明电导的测定结果与相图吻合的很好。其次,绘制了45℃及65℃下,SDS/正戊醇-环己烷-水、SDS/正戊醇-环己烷-硝酸锌水溶液和SDS/正戊醇-环己烷-氢氧化钠水溶液体系的拟三元相图并对6个相图进行了比较,研究了碱(NaOH)和盐(Zn(NO_3)_2)对SDS/正戊醇-环己烷-水拟三元体系相图影响。结果表明,硝酸锌及碱的加入使SDS/正戊醇-环己烷-水拟三元相图水包油(O/W)和油包水(W/O)区域明显的缩小。45℃时,SDS/正戊醇-环己烷-氢氧化钠水溶液体系的拟三元相图中的O/W区域甚至消失;65℃时,O/W和W/O区域均存在,且3个相图的W/O和O/W区域有重叠区。在此基础上,确定了制备纳米Zn O的微乳液的条件,即SDS/正戊醇-环己烷-硝酸锌水溶液和SDS/正戊醇-环己烷-氢氧化钠水溶液体系的拟三元相图中W/O区域的重叠区(各相图中的Ⅱ区)。制备的纳米氧化锌为多晶结构,平均粒径为80 nm。     

Y2P2W18O62?nH2O/4A-分子筛的研制及其催化合成乙酰水杨酸

以4A-分子筛为载体,Dawson结构磷钨酸钇（Y2P2W18O62?nH2O）为活性组分,采用浸渍法制备出负载型40% Y2P2W18O62?nH2O/4A-分子筛,并通过FT-IR、EDS、SEM、NH3-TPD及N2吸附-脱附等方法对催化剂进行表征。将其用于催化水杨酸和乙酸酐反应制备乙酰水杨酸,考察了各因素对反应的影响。结果表明：负载前后磷钨酸钇均保持Dawson结构,Y2P2W18O62?nH2O和40% Y2P2W18O62?nH2O/4A-分子筛均呈球形,负载后催化剂的比表面积增大,酸强度和酸量均明显提高。在优化反应条件下,即水杨酸与乙酸酐摩尔比为1:3,反应时间为30min,催化剂用量为反应物质量分数的2.3%,乙酰水杨酸收率为95.2%。催化剂重复使用6次,乙酰水杨酸收率仍保持为77.9%。     

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.     

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。     

聚合反应介质对丙烯腈/衣康酸共聚物结构与性能的影响

利用混合溶剂沉淀聚合法研究了水/环丁砜(H_2O/TMS)等4种不同聚合反应介质对丙烯腈/衣康酸(AN/IA)共聚物的转化率、重均分子量(Mw)及分布(D)、表面微观形貌、竞聚率及链结构、聚合物热性能和纺丝性能的影响.结果表明,P(AN/IA)聚合物转化率随着混合溶剂中H_2O含量的增加,呈先升高后降低的趋势.P(AN/IA)的Mw与水/溶剂比例成线性增加的关系,其中,以H_2O/TMS作为混合反应介质所制备P(AN/IA)的Mw最大,D最小(小于2).AN与IA以H_2O/TMS为聚合介质时倾向于理想共聚,2IA链段分布几率仅为2.87%.以H_2O/TMS为聚合体系所制备P(AN/IA)结构疏松、颗粒粒径较小且易溶解,预氧化时环化反应放热速率低、放热区间宽,热稳定化阶段形成耐热梯形结构反应所需能垒小.P(AN/IA)/TMS纺丝溶液的表观黏度低,TMS为PAN的良溶剂.     

Transfer and distribution of L-tryptophan between W/O and O/W, and between W/O and bicontinuous microemulsions through the study of interphase electric properties

The influence of L-tryptophan (L-Trp) on the interphase electric properties of sodium dodecyl sulfate (SDS)/n-pentanol (n-C(5)H(11)OH)/water (H(2)O) system was studied by the method of AC impedance, and the distribution of L-Trp between the microemulsion phases with different structures in SDS/n-C(5)H(11)OH/H(2)O system was determined by UV-vis spectroscopy. The results show that L-Trp transfers from the lower phase (O/W or bicontinuous) to the upper phase (W/O), and that a small amount of SDS transfers from the upper phase to the lower phase correspondingly with the increase of the total SDS content at a constant weight ratio of n-C(5)H(11)OH/H(2)O=50/50 and a total L-Trp concentration of 1.0 x 10(-4) mol/L. In addition, the concentrations of L-Trp in both the upper and lower phases increase, but the SDS content decreases slightly in the upper phase and increases appreciably in the lower phase with the increase of the total L-Trp concentration at a constant total content of SDS. The interphase capacitance and the interphase charge-transfer current of the system increase, but the interphase resistivity decreases.     

SDS/n－C5H11OH/n－C7H16/H2O体系中W/O－BI微乳液界面电性质

In the system of SDS/n-C5H11OH/n-C7H16/H2O with the weight ratio of SDS/n-C5H11OH/H2O system at5.0/47.5/47.5, the upper phase of the system was W/O microemulsion, and the lower phase was the bicontinuous microemulsion. When the n-heptane content was less than 1%, with the increase of the n-heptane content, the capacitance (Co, Cod) in the upper phase (W/O) dropped, the capacitance (CB1, CBld) in the lower phase (BI) raised. At the same time, the W/O-BI inteffacial potential (ΔE), capacitance (Ci), and charge-transfer current (ict) decreased.After the n-heptane content reached 1%, with the increase of the n-heptane content, ΔE, Ci and ict demonstrated no significant change.     

Distribution and Transfer of Gatifloxacin Between Two Microemulsion Phases with Different Structures in SDS/n-C5H11 OH/H2O System

At a weight ratio of n‐C₅H₁₁OH/H₂O=50/50, when the total content of sodium dodecyl sulfate (SDS) was less than 6.0%, the ternary mixture of SDS/n‐C₅H₁₁OH/H₂O coexisted in two immiscible microemulsions. The distribution and transfer of gatifloxacin (GTFX) between the two phases were studied using UV‐Vis and electrochemistry AC impedance spectra. The results show that GTFX transferred from the upper phase (W/O) to the lower phase (O/W or bicontinuous microemulsion), but a small amount of SDS transferred from the lower phase to the upper phase correspondingly with the increase of the total SDS content at a total GTFX concentration of 1.0×10^?5 mol/L. The addition of GTFX did not change the structures of the two different phases fundamentally, but resulted in the transfer and redistribution of GTFX and SDS, so the electric properties of the system were changed correspondingly.     

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。     

Incomplete phase inversion W/O/W emulsion and formation mechanism from an interfacial perspective

Water-in-oil-in-water (W/O/W) double emulsion can be prepared by incomplete phase inversion method using both medium chain triglycerides (MCT) and isopropyl myristate (IPM) as oil phase, Span 85-Tween 80 (HLB values of 2.5-3.0) as mixed emulsifiers. The preparation method was simple, and the final double emulsions were proved of good microstructure and particle size distribution. Owning to the addition of Tween 80 to Span 85, interfacial tension, interfacial viscosity and modulus decreased, which contributed to the phase inversion. Furthermore, formation of reverse micelles under high-speed dispersion may be a hypothesis to explain the incomplete phase inversion phenomenon.     

Stabilization of O/W emulsion with hydrophilic/hydrophobic clay particles

In this study, a stabilizing behavior of clay in a 40/60 w/w oil-in-water (O/W) emulsion is investigated by macro- and microscopic morphological observations, rheology, and X-ray diffraction measurements. Hydrophilic and hydrophobic clays (Montmorillonites) are tested for stabilization of emulsion. When hydrophilic clay showing interfacial localization is added to the emulsion, emulsion is not stable to phase separation (creaming). With hydrophobic clay, the emulsion shows phase inversion to water-in-oil (W/O) emulsion due to the increase in oil viscosity which results in phase separation of sedimentation. On the other hand, with the mixture of hydrophilic and hydrophobic clays, the emulsion shows a synergistic macroscopic and microscopic stabilization due to the formation of composite structure at the interface by hydrophilic and hydrophobic clays.     

Relationship between rheological properties and one-step W/O/W multiple emulsion formation

Formation of a normal (not temporary) W/O/W multiple emulsion via the one-step method as a result of the simultaneous occurrence of catastrophic and transitional phase inversion processes has been recently reported. Critical features of this process include the emulsification temperature (corresponding to the ultralow surface tension point), the use of a specific nonionic surfactant blend and the surfactant blend/oil phase ratio, and the addition of the surfactant blend to the oil phase. The purpose of this study was to investigate physicochemical properties in an effort to gain a mechanistic understanding of the formation of these emulsions. Bulk, surface, and interfacial rheological properties of adsorbed nonionic surfactant (CremophorRH40 and Span80) films were investigated under conditions known to affect W/O/W emulsion formation. Bulk viscosity results demonstrated that CremophorRH40 has a higher mobility in oil compared than in water, explaining the significance of the solvent phase. In addition, the bulk viscosity profile of aqueous solutions containing CremophorRH40 indicated a phase transition at around 78 ± 2 °C, which is in agreement with cubic phase formation in the Winsor III region. The similarity in the interfacial elasticity values of CremophorRH40 and Span80 indicated that canola oil has a major effect on surface activity, showing the significance of vegetable oil. The highest interfacial shear elasticity and viscosity were observed when both surfactants were added to the oil phase, indicating the importance of the microstructural arrangement. CremophorRH40/Span80 complexes tended to desorb from the solution/solution interface with increasing temperature, indicating surfactant phase formation as is theoretically predicted in the Winsor III region. Together these interfacial and bulk rheology data demonstrate that one-step W/O/W emulsions form as a result of the simultaneous occurrence of phase-transition processes in the Winsor III region and explain the critical formulation and processing parameters necessary to achieve the formation of these normal W/O/W emulsions.     

STATISTICAL MECHANICAL MODEL THEORY OF THE STABILITY OF O/W AND W/O MICROEMULSIONS

A theoretical model to clarify the molecular origin of the mechanical and thermal stabilities of O/W or W/O microemulsion is proposed in which the low concentration of surfactants (emulsifiers) is limited. We assume only a short range interaction between surfactants and a bending stiffness energy which expresses the deformation energy from a preferable monolayer membrane curvature. We have found an interrelation among the interfacial pressure, Δp, of the monolayer due to the adsorption of surfactants in the microemulsion interface, interfacial tensions of oil-water interface and of the microemulsion, and the bending stiffness energy. We conclude that the interfacial tension and the stable form of the microemulsions (O/W type or W/O type) are infuenced largely by the effect of the bending stiffness energy. The interrelationship between the therraodynamical and mechanical stabilities of microemulsions is clarified by the use of our assumption.