表面张力法和电导法对比测定表面活性剂临界胶束浓度*

通过比较表面张力法和电导法测定阴离子表面活性剂十二烷基硫酸钠(SDS)和非离子表面活性剂辛基酚聚氧乙烯醚(TX-100)的临界胶束浓度的实验效果,明确了2种方法的优劣。 采用挂环法测试了不同浓度SDS和TX-100水溶液的表面张力,得到了它们的临界胶束浓度以及饱和吸附量、分子截面积;采用电导法研究上述2种表面活性剂溶液的电导率曲线,仅得到SDS的临界胶束浓度。与电导法相比,表面张力法得到的表面活性剂性质信息更多,应用更广泛。该实验使学生加深理解不同电性表面活性剂临界胶束浓度的性质及测定方法,明确不同方法的优缺点,扩大知识面,同时也提高学生处理数据的能力,为学生今后进一步学习应用表面活性剂打下良好基础。     

Quantitative Structure—Property Relationship on Prediction of Surface Tension of Nonionic Surfactants

When a surfactant is solved into a solvent, it will adsorb onto the surface of the solution and reduce the surface free energy to a marked degree. The surface free energy, which is the minimum amount of work required to create that surface, is usually measured by surface tension. The minimum of surface tension 0g is the most useful key for characterizing the activity of surfactant. It is well known that 0g is determined by the molecular structure of surfactant, i.e., the contributions from …     

阳离子和两性表面活性剂对石英表面润湿性的影响

利用座滴法研究了阳离子表面活性剂十六烷基醚羟丙基季铵盐(C16PC)和两性离子表面活性剂十六烷基醚羟丙基羧酸甜菜碱(C16PB)溶液在石英表面上的润湿性质, 考察了表面活性剂类型及浓度对接触角的影响趋势, 讨论了黏附张力和黏附功的变化规律. 研究发现, 两种表面活性剂在高能的石英表面的吸附造成石英-水的界面自由能(γsl)增大. C16PB通过弱相互作用随机吸附到石英表面, 其增大γsl的能力与降低表面张力(γ1g)的能力相当, 接触角(θ)随浓度变化不大. C16PC 随体相浓度增大能够在石英表面通过静电作用形成定向排列的单分子层, 而后在临界胶束浓度(cmc)附近形成双层结构, 接触角随浓度变化的趋势可分为4个区域, 并通过一个极大值.     

CnNCl和SDS在水溶液中的相互作用

CnNCl和SDS在水溶液中的相互作用;滴定式微量热法; 烷氧基羟丙基三甲基氯化铵; 十二烷基硫酸钠;胶束;疏水作用     

Interaction Between Surfactin and Bovine Serum Albumin

The interaction of surfactin, a typical biosurfactant, with bovine serum albumin (BSA) was investigated by surface tension, fluorescence, freeze-fractured transmission electron microscopy (FF-TEM) and circular dichroism (CD) measurements. The surface tension curves of pure surfactin solution and surfactin/BSA solutions have different phenomena, where two obvious inflections determined as the critical aggregation concentration (cac) and the critical micelle concentration (cmc) appear for surfactin/BSA solutions. The higher BSA concentration, the higher cac and cmc values for surfactin/BSA solution. Fluorescence spectra show that the structure change of BSA is dependent on both surfactin and BSA concentration. The micropolarity, FF-TEM and CD results further demonstrate the interaction between BSA and surfactin. The excess free energy (ΔG⁰) of surfactin/BSA interactions have been obtained as ?6.13 and 5.32 kJ/mol for 1.0 × 10^?6 and 3.8 × 10^?6 mol/L BSA concentration, respectively. The binding ratio (R) determined for surfactin/BSA systems are higher than that reported for dirhamnolipid to BSA. Above all, it can be concluded that the hydrophobic interaction and the hydrogen bonds between surfactin and BSA play the key role for the high binding ratio for surfactin to BAS.     

Synthesis,Characterization, and Surface Properties of Cationic Gemini Surfactants

New pyridinium gemini surfactants have been synthesized by esterification of renewable fatty acids with mercaptoethanol furnishing respective esters (mercaptomethyl decanoate, mercaptomethyl dodecanoate, mercaptomethyl tetradecanoate, mercaptomethyl hexadecanoate) followed by their subsequent treatment with 4-dimethyl amino pyridine resulting in the formation of title gemini surfactants: 1-(5-(decanoyloxy)-2-hydroxypentyl)-4-((5-(decanoyloxy)-2-hydroxypentyl)dimethyl ammonio)pyridin-1-ium chloride (9), 1-(5-(dodecanoyloxy)-2-hydroxypentyl)-4-((5-(dodecanoyloxy)-2-hydroxypentyl)dimethyl ammonio)pyridin-1-ium chloride (10), 1-(5-(tetradecanoyloxy)-2-hydroxypentyl)-4-((5-(tetradecanoyloxy)-2-hydroxypentyl)dimethyl ammonio)pyridin-1-ium chloride (11), and 1-(5-(hexadecanoyloxy)-2-hydroxypentyl)-4-((5-(hexadecanoyloxy)-2-hydroxypentyl)dimethyl ammonio)pyridin-1-ium chloride (12). Their identifications are based on infrared, ¹H NMR, ¹³C NMR, distortionless enhanced polarization transfer, co-relational spectroscopy (COSY), and mass spectral studies. Their surface active properties are also evaluated on the basis of surface tension and conductivity measurements. Thermal stability of these long chain cationic gemini surfactants have been measured by thermal gravimetric analysis under nitrogen atmosphere.     

PLA-mPEG嵌段共聚物胶团的制备及其表面张力

PLA-mPEG嵌段共聚物胶团的制备及其表面张力;丙交酯;甲氧基聚乙二醇;嵌段共聚物;纳米胶团;表面张力     

Investigation Static/Dynamic Surface and Interfacial Tension of Some Synthesized Polymeric Surfactants to Enhance the Egyptian Jet Fuel A1 Atomization

In the present work some exthoxylated polyalkylphenol surfactants have different alkyl chains (nonyl and dodecyl) were synthesized. The static surface tension for these surfactants in water and jet fuel A1 was measured and the critical micelle concentration (CMC) for each surfactant was determined. The data show the general trend of decreasing the CMC against the molecular weight of the synthesized polymeric surfactants. The HLB of these surfactants was also calculated. The dynamic surface tension for the synthesized surfactants was measured at CMC. The dynamic interfacial tension for these surfactants with jet fuel A1 at CMC was also measured using the spinning drop technique. The results showed that the effect of the synthesized surfactants on deceasing the time of droplet maturation was significant remarked. The decrease of this time leads to enhance of jet fuel atomization.     

Walnut Oil Nanoemulsion: Optimization of the Emulsion Capacity,Cloudiness, Density,and Surface Tension

Response surface methodology (RSM) in conjunction with central composite rotatable design (CCRD) was employed to find out the influence of preparation properties of walnut oil/water nanoemulsion namely ultrasonic time (5–15 minutes), walnut oil content (4–10% w/w) and concentration ratio of Span 80 to Tween 80 (K ₀, 0.55–0.80) on response variables including emulsion capacity, cloudiness, density and surface tension. The calculated regression models with high value of coefficient of determination (0.910–0.973) and insignificant lack of fit test indicated satisfactory agreement of empirical models with experimental observations. The results revealed linear term of walnut oil concentration was the most significant (p < 0.05) parameter on the all responses. The overall optimum region to achieve the ideal characteristics was ultrasonic time of 11.74 minutes, walnut oil content of 4.00% (w/w) and K ₀ of 0.80.     

An Unusual Variation of Surface Tension with Concentration of Mixed Cationic‐anionic Surfactants

There are two platforms in the surface tension vs. concentration curve (γ‐lgC curve) of cationic‐anionic surfactant mixtures. The first platform is the same as that of common surfactant solution, and the cross point is the CMC. After the CMC, the mixtures form precipitate. At higher concentration, the mixtures form homogeneous solution again. When the mixtures form homogeneous solution at high concentration, surface tension increases with concentration, then becomes constant. So the γ‐lgC curve exhibits the second platform. The surface tension at the second platform increases by increasing molar ratio of two surfactants and polar group size of surfactants, and decreases with adding inorganic salts.     

Ultra-Low Interfacial Tension Between Heavy Oil and Betaine-Type Amphoteric Surfactants

Betaine surfactants with lipophilic groups of different lengths were synthesized in this research and the dynamic interfacial tension (IFT) between solutions of these surfactants and three kinds of crude oil from Shengli Oilfield are measured. The results indicated that, for Gudao and Gudong heavy oil, cetyl dimethyl hydroxyl sulfobetaine (SBET-16) was the most efficient in lowering the IFT in the case of no alkalis, while for Shengtuo heavy oil, cetyl dimethyl carboxymethyl betaine (CBET-16) was best. SBET-16 with the concentration of 0.003–0.1% and 0.005–0.1% can reduce the oil/water IFT to ultra-low for Gudao and Gudong oil respectively, CBET-16 with the concentration of 0.005–0.1% can lower the oil/water IFT to ultra-low for Shengtuo oil. These results showed that for different oils, an oil displacement agent with high capacity to lower the oil/water interfacial tension may be obtained only by changing the molecular structure of betaine surfactant. This study can be used to guide the design of surfactants for alkaline-free combination flooding.     

阴离子表面活性剂与聚丙烯酰胺间的相互作用

聚集体;阴离子表面活性剂与聚丙烯酰胺间的相互作用     

Temperature Dependence of the Surface Tension of Alkali Metals: A Unified Correlation

Abstract

In this work, new definitions of the normalized temperature and surface tension are proposed which result in a single plot for the surface tension of molten alkali metals. The functional dependence of the reduced surface tension on the reduced temperature can be adequately described by a straight line; the intercept and slope have been obtained using the linear regression approach. The method proposed herein predicts the values of surface tension at various temperatures with an average error of about 5%.     

最大泡压法测表面张力等温线的数据处理方法比较*

对乙酸、丙酸、正丁酸、2-甲基丁酸、3-甲基丁酸、正戊酸、正己酸、乙醇、丙醇、异丙醇、正丁醇、异丁醇、1,2-丙二醇等13种常用试剂在25 ℃下的表面张力数据拟合方法进行了比较,分析了图解法处理数据及多项式、一阶指数函数、幂函数、Shishkovsky经验公式拟合数据的优缺点。指出Shishkovsky经验公式拟合结果准确,受数据样本量影响小,是理想的表面张力数据拟合方法。     

理想混合表面活性剂表面张力的计算公式及实验验证

采用Newton迭代法, 给出了两种计算二组分表面活性剂理想混合体系表面张力的显函数简捷表达式, 并通过膦氧化物同系物, 季铵盐混合体系, 以及全氟辛酸铵和全氟壬酸铵混合系列表面张力的实验值和数值解对其精确性进行了验证. 结果表明, 两种迭代法都有很快的收敛速度, 表达式的相对误差都在1%之内.     

润滑剂分子结构与粘度和表面张力的定量关系

用偏最小二乘法(PLS)和人工神经网络(ANN)方法对润滑剂分子结构与表面张力和粘度之间的关系进行了定性分析和定量计算,采用的结构参数有分配系数、分子体积、分子表面积、溶度积、摩尔折射度和等张比容。定性分析结果与实验结果一致,定量计算结果与实验结果符合较好。     

Direct Correlation of Surface Tension and Surface Composition of Ionic Liquid Mixtures—A Combined Vacuum Pendant Drop and Angle-Resolved X-ray Photoelectron Spectroscopy Study

We investigated the surface tension and surface composition of various mixtures of the two ionic liquids (ILs) 1-methyl-3-octyl-imidazolium hexafluorophosphate [C₈C₁Im][PF₆] and 1,3-bis(polyethylene glycol)imidazolium iodide [(mPEG₂)₂Im]I in the temperature range from 230 to 370 K under ultraclean vacuum conditions. The surface tension was measured using a newly developed apparatus, and the surface composition was determined by angle-resolved X-ray photoelectron spectroscopy (ARXPS). In the pure ILs, the alkyl chains of [C₈C₁Im][PF₆] and the PEG chains of [(mPEG₂)₂Im]I are enriched at the IL/vacuum interface. In the mixtures, a strong selective surface enrichment of the alkyl chains occurs, which is most pronounced at low [C₈C₁Im][PF₆] contents. For the surface tension, strong deviations from an ideal mixing behaviour take place. By applying a simple approach based on the surface composition of the mixtures as deduced from ARXPS, we are able to predict and reproduce the experimentally measured temperature-dependent surface tension values with astonishingly high accuracy.     

正负离子表面活性剂与非离子表面活性剂混合水溶液的相互作用

非离子表面活性剂的加溶作用有助于正负离子表面活性剂的溶解,在恰当比例时,能基本保持其表面活性;正负离子表面活性剂与非离子表面活性剂之间的相互作用很弱,容易形成接近“理想”的混合胶团;恒定非离子表面活性剂浓度时,随正负离子表面活性剂浓度增加,溶液的浊点也增加;超过临界胶团浓度后浊点下降。     

缩水甘油苯基醚-缩水甘油正丁基醚共聚物磺酸钠的合成及表面活性

缩水甘油苯基醚-缩水甘油正丁基醚共聚物磺酸钠的合成及表面活性;缩水甘油苯基醚-缩水甘油正丁基醚共聚物磺酸钠; 合成; 表面性质; 胶束