荧光探针法研究新型Gemini表面活性剂在水溶液中的聚集行为

以芘为荧光探针、二苯酮为猝灭剂,用稳态荧光探针法测定了新型Gemini表面活性剂的临界胶团浓度(CMC)、胶团聚集数(N_agg)及胶团微极性.研究了Gemini表面活性剂结构和氯化钠浓度对CMC、N_agg、胶团微极性的影响.结果表明,新型Gemini表面活性剂的CMC比常规表面活性剂的CMC低1—2个数量级.当疏水基碳原子数增加时,CMC依次降低,N_agg增大,胶团微极性减小.当氯化钠浓度增大时,N_agg增大,胶团微极性减小.     

改性二氧化硅纳米颗粒提高二氧化碳泡沫稳定性的研究

通过纳米二氧化硅的硅烷化改性,使其在高矿化度盐水中可以稳定存在的前提下,研究了改性纳米颗粒与阳离子表面活性剂十二烷基三甲基氯化铵混合体系的溶液稳定性及协同稳定CO₂泡沫的效果.研究结果表明,无机盐离子对改性纳米颗粒与阳离子表面活性剂间的静电吸引力具有屏蔽作用,且矿化度越高,屏蔽效果越明显,从而混合溶液更易于在高盐水中稳定;纳米颗粒表面的活性剂吸附层受二者浓度的影响,进而影响了颗粒的亲/疏水性;当混合体系中的表面活性剂浓度低于临界胶束浓度(CMC)时,混合溶液与CO₂的界面张力高于单独活性剂溶液,而当活性剂浓度高于CMC时,对CO₂-溶液界面张力几乎无影响,最低界面张力可降至6 mN/m左右;改性纳米颗粒的加入可以进一步提高CO₂体相泡沫半衰期一倍以上,但受二者浓度比例的影响;纳米颗粒的加入有效提高了多孔介质中泡沫的表观黏度,最大增幅由20 mPa·s增至55 mPa·s左右,泡沫黏度增加接近3倍,增强了CO₂泡沫驱的封堵作用.     

支链醇对Gemini表面活性剂表面活性和胶束化行为的影响

Gemini表面活性剂是一类高效的新型表面活性剂,而醇是工业界和日化领域最常采用的表面活性剂助剂,因此研究不同结构的醇对Gemini表面活性剂表面活性和胶束化行为的影响规律和机理对于促进Gemini表面活性剂的发展和实际应用具有重要意义.利用表面张力、电导、等温滴定微量热,低温透射电镜和核磁共振研究了直链醇1-戊醇和具有相同主链的支链醇2-己醇与3-庚醇对具有不同长度连接基团阳离子季铵盐型Gemini表面活性剂C₁₂C_SC₁₂Br₂ （S=2,4,6,8,10,12）的表面活性和胶束化行为的影响,结果发现,支链醇能够显著影响表面活性剂在气/液界面的排布,使得C₂₀ （使溶剂的表面张力降低20 mN/m所需的表面活性剂浓度）和γ_CMC （CMC时表面张力值）随醇支化度的增加而显著降低,而支链醇对表面活性剂在溶液中的临界胶束浓度以及胶束的尺寸和形貌均没有明显影响,同时这些醇对Gemini表面活性剂的影响与连接基团的长度相关.阐述了上述结果产生的机理,将有助于指导如何选择合适结构的醇助剂去调控Gemini表面活性剂的表面和溶液性质.     

C12-m-C12型阳离子Gemini表面活性剂在煤沥青表面的润湿性

利用座滴法和电泳法研究了阳离子Gemini表面活性剂C₁₂-m-C₁₂·2Br^-(m=4、6、8、10)在煤沥青表面的润湿性质及吸附机理。结果表明, 表面张力均随表面活性剂浓度的增大而减小, 超过临界胶束浓度(CMC)后趋于平稳, 接触角θ和铺展系数S的变化趋势与表面张力类似; 在所研究浓度范围内,C₁₂-10-C₁₂型表面活性剂的γ_lg~cosθ曲线符合Zisman理论, 且侵湿功(W_i)与表面张力也呈线性关系; 煤沥青表面的Zeta电位随表面活性剂浓度的增加从负电变为正电,最后趋于平稳, 且零电位对应的浓度比CMC至少低一个数量级; C₁₂-8-C₁₂型Gemini表面活性剂能显著改变煤沥青表面的润湿性. 由Gemini表面活性剂在煤沥青表面润湿结果及Zeta电位可以看出, C₁₂-m-C₁₂型Gemini表面活性剂在煤沥青表面的润湿是静电作用和范德华吸附共同作用的结果; 润湿过程可分为三个阶段。     

表面活性剂对分散体系粘度影响的特殊性

通过液体石蜡的水基化分散对影响分散体系粘度的粒子大小、表面活性剂胶束和界面膜等因素进行了研究.结果表明,表面活性剂胶束对分散体系粘度的影响极为有限,而在分散相粒子界面上由表面活性剂分子所形成的界面膜是导致分散体系粘度产生变化的重要因素.实验数据表明,对于分散体系的稳定性,存在一个表面活性剂浓度变化的临界值,而该临界值所对应的是表面活性剂分子在粒子表面以最紧密和规整的方式形成的界面膜,该种界面膜使分散体系粘度达到最大值,从而最大限度地保证了分散体系的稳定性.     

壬基酚聚氧乙烯醚在油相中的CMCo及相关问题研究

对壬基酚聚氧乙烯醚在油相中的临界胶束浓度(CMC_o)及与之相关的问题进行了研究,并获得了部分CMC_o值.对CMC_o与表面活性剂自身结构的关系进行分析和数学处理后,发现CMC_o与活性物质自身结构间仍为对数关系.同时在对某些具体体系的界面张力随表面活性剂不同而发生的变化进行了详细分析,发现CMC_w和CMC_o是评价表面活性剂性能的有效工具.     

Sn(MSA)2电镀液体系表面活性剂性能优化的模拟研究

在本工作中,我们利用粗粒化分子动力学(MD)模拟方法,研究了两亲性表面活性剂构型及浓度对Sn(MSA)₂类电镀液体相溶液与铜基板周围电镀液微观结构的影响,从分子水平系统考察了主盐离子、表面活性剂与甲醛添加剂的分布和聚集情况,及其与铜基板的相互作用.研究表明,A₄B₁₂型表面活性剂的疏水链段(A₄)协同效应较强,易在溶液中形成胶束,在基板上吸附能力有限;A₂B₁₂A₂疏水链较短,B₆A₄B₆疏水链居中,该两种表面活性剂在溶液中难以聚集,易充分吸附于基板之上;(AB₃)₄型表面活性剂在体相溶液中充分分散,在基板上的吸附能力有限.A₂B₁₂A₂及B₆A₄B₆型表面活性剂的充分吸附,有助于金属离子及甲醛添...     

正离子Gemini表面活性剂/负离子聚电解质相互作用的研究

摘要 采用荧光探针法和电导法研究了正离子偶联表面活性剂(C₁₂H₂₅(CH₃)₂N-(CH₂)₆-N(CH₃)₂C₁₂H₂₅•2Br) (12-6-12• 2Br^－)和带相反电荷聚电解质聚丙烯酸钠(NaPA)的相互作用, 结果表明: 由于静电相互作用, 12-6-12•2Br^－和NaPA之间可以形成类胶束或复合物. 对比十二烷基三甲基溴化铵(DTMAB)与NaPA复配体系的荧光光谱, 发现偶联表面活性剂与NaPA的相互作用强于传统表面活性剂. 此外, 还研究了盐和醇对偶联表面活性剂/聚丙烯酸钠的复配体系微极性的影响, 发现盐和醇对表面活性剂在聚电解质上形成类胶束和复合物的溶解都有一定的促进作用.     

混合表面活性剂在非极性溶剂中的聚集行为

表面活性剂在非极性溶剂中的聚集行为比在水溶液中复杂得多. 水溶液中表面活性剂有一明确的临界胶束浓度(CMC),而在非极性溶剂中至今对CM C概念仍有怀疑^[1], 但已有多种手段如染料增溶法、水增溶法、光散射法、荧光偏振、紫外和核磁共振谱等证实并测定了非极性溶剂中 CMC 的存在^[1～5]. 表面活性剂在非极性溶剂中以非离子化状态存在, 其缔合主要靠两亲分子之间的偶极-偶极以及离子对相互作用, 那么在一种表面活性剂溶液中加入另一种表面活性剂, 即表面活性剂的复配, 必然对其聚集行为产生重大影响, 但迄今为止, 尚未见关于混合表面活性剂在非极性溶剂中聚集行为的报道. 本文采用碘光谱法和水增溶法测定了阴离子表面活性剂AOT 和非离子表面活性剂 Brij30 混合后在正庚烷中形成反胶束的 CMC, 以期考察表面活性剂的复配对其聚集行为的影响。     

不同体系中油酸甲酯与烷基苯磺酸盐协同效应研究

研究了表面活性剂/盐/模拟油体系与表面活性剂/碱/模拟油体系中油酸甲酯与表面活性剂协同效应机理.结果表明两种体系中协同效应机理不同.在盐体系中,油酸甲酯主要通过改变油相的等效烷烃碳数(EACN) 影响表面活性剂在油水相分配.而碱体系中,油酸甲酯影响表面活性剂在油水相分配从而影响界面张力；另一方面,油酸甲酯吸附在界面上顶替表面活性剂分子影响界面张力.对于不同结构表面活性剂,两种作用竞争的结果不同.     

Polymeric surfactants with tricyclic rigidity from natural rosin: Synthesis and dispersion of single-walled carbon nanotubes in aqueous solution

Polymeric surfactants from natural rosin containing a unique tricyclic rigid structure were prepared and their structures were characterized by IR, ¹H NMR and GPC. Their surface activities including hydrophile—lipophile balance values (HLB), emulsification properties, foaming properties, critical micelle concentration (CMC) and the minimum surface tension (γCMC) were evaluated. With the increase in ratio of hydrophobic to hydrophilic in polymeric surfactant, the CMC values of the surfactants decreased, and the emulsification and foaming properties of these surfactants increased, and the HLB values of them decreased. This type of polymeric surfactants was used to disperse single-walled carbon nanotubes (SWCNTs) in water, and their dispersal capacities were comparatively determined by UV-visible absorption spectroscopy. Thermogravimetric analysis (TGA) was used to quantify the amount of surfactant attached onto the nanotubes. More intuitive image of their dispersion states were obtained by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The results showed that this type of polymeric surfactants had good dispersion capacity and dispersion stability to SWCNTs in water through strong hydrophobic attraction and weak van der Waals interactions.     

Extension of the Taylor Equation for Oil-Water-Surfactant System and Investigating the Impact of Surfactant Concentration over the Quality of Emulsion

Emulsions stand among the most important multiphase fluids, exhibiting various complicated phenomenon. To understand the process of emulsification, the Taylor equation has been extended to incorporate the parameters that depend on molecular mass of oil and their contents and the amount of surfactant added. To test the validity of the proposed equations, four well-defined short chain (n-hexane, n-heptane, n-decane, and kerosene) oils were emulsified in water and the results were compared with the experimental ones. It has been concluded that the extended Taylor equation worked well, even in the presence of surfactant. The quality of the emulsion defined and discussed in terms of size and number of droplets was best near CMC of the surfactant used. A relationship has also been derived between CMC of surfactant and its distribution coefficient, which allows the exact value of one parameter to be determined if other is known.     

Synthesis and properties of α-sulfo carboxyl disodium salt

The synthesis and properties of α-sulfo carboxyl disodium salt (SCDS) were studied in detail for the first time in this paper. SCDS was synthesized via saponification reaction of fatty acid methyl ester sulfonate sodium (MES). FT-IR was used to characterize the molecular structure of target product. The yield of disodium salt was greater than 98% by two-phase titration. The performance of SCDS was studied and was compared with raw materials MES, conventional anionic surfactant AES and nonionic surfactant AEO₉. The result shows SCDS can reduce the surface tension of the solution to 27.89?mN/m at critical micelle concentration (CMC). The wetting ability of SCDS was significantly enhanced with the increase of temperature. The emulsification effect of SCDS on the soybean oil is better than that on the liquid paraffin. Surprisingly, SCDS has a good foamability and foaming stability.     

Effects of a Novel Organic Alkali on the Interfacial Tension and Emulsification Behaviors Between Crude Oil and Water

Experiments have been carried out to investigate the interfacial tension (IFT) and emulsification behaviors between Shengli crude oil and a novel organic alkali (OA). The dynamic IFT and minimum IFT are adopted to characterize the IFT behaviors; the microscopic method, Turbiscan stability index, separated water rate, and laser particle size analysis method are used to show the emulsification behaviors. The dynamic and minimum IFT both decrease continuously with the increase of OA concentration whether surfactant is added or not; because of the synergy of OA and surfactant, the minimum IFT will be reduced to the ultralow value. The synergy is also crucial for the crude oil emulsification. When OA and surfactant are used together, owing to the mosaic and cross-multiple adsorption of OA, surfactant and in situ soap at the interfacial film, the oil can be emulsified more easily, the quantity of emulsified droplets is higher, and the emulsion is more stable with OA concentration increases. The relationship of the minimum IFT and emulsification is investigated; it indicates that the emulsion stability improves, the degree of dispersed homogeneity of oil droplets increases, and the median diameter of emulsified oil droplets decreases with the decline of the minimum IFT.     

Compositional Analysis and Adsorption Performance of Surfactants Used for Combined Chemical Flooding

Adsorption of surfactants on reservoir sands in a combined chemical flooding process was investigated using a microcosmic method in order to reveal the effects of surfactant composition on their adsorption. Alkylbenzenesulfonate types of surfactant have been used in this study. The experimental results indicate that surfactant adsorption on the sands heavily depends on its lipophilicity, and the adsorption quantity increases with increasing the lipophilic chain length of the surfactant. It was found that the saturated adsorption could be reached when the concentration of the surfactant was near the critical micelle concentration (CMC). For oilfield applications, the molecular ion peak of the alkylbenzene‐sulfonate type surfactants should concentrate at around C₁₈.     

System peaks in micellar electrophoresis: I. Utilization of system peaks for determination of critical micelle concentration

A new way to determine the critical micelle concentration (CMC) based on the mobilities of system peaks is presented. A general approach for the CMC determination is based on the change of the slope or on finding the inflection point in the plot of a physical property of solution as a function of surfactant concentration. The determination of CMC by system peaks in CE utilizes a "jump" instead of a continuous change in the measured quantity. This phenomenon was predicted by the program PeakMaster, which was modified for simulation of micellar systems. The simulation of the steep change in mobilities of the anionic system peaks showing the CMC value was verified experimentally in a set of measurements, where the concentration of the surfactant was varied while the ionic strength was kept constant. The experimental work fully proved our model. A comparative electric current measurement was carried out. The proposed method seems to offer easier CMC determination as compared to the standard methods.     

Stability Characteristics of Dispersed Oil Droplets Prepared by the Microchannel Emulsification Method

A novel emulsification method, microchannel (MC) emulsification, was developed for making monodispersed regular-sized droplets in our laboratory. An oil-in-water dispersed system, in which phosphate buffer was used as the continuous phase, sodium dodecyl sulfate (SDS) as the surfactant, and clove oil as the dispersed phase, was prepared by this technique. The average diameter of oil droplets was about 20 μm, with a narrow size distribution. The stability characteristics of the dispersed oil droplets were investigated by an optical microscope and kinetic light scattering method. The stability of the dispersed oil droplets depended on the SDS concentration. When the SDS concentration was above the critical micelle concentration (CMC), the turbidity of the dispersed solution sharply increased at the initial stage. Optical microscopic observation has confirmed that a part of the oil droplets broke up with time, and submicrometer droplets appeared. On the other hand, when the SDS concentration was below the CMC, the turbidity of the dispersed solution had little change in the initial stage, showing that the oil droplets were very stable. The effect of ion concentration was also examined. The results showed that the stability of the oil droplets depended on the balance of the Van der Waals attraction and electrical repulsion between the oil droplets in low ion concentration. Copyright 2001 Academic Press.     

Characterization and demulsification of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) copolymers

Four poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) copolymers with different molecular weights and PPO/PEO composition ratios were synthesized. The characterization of the PEO-PPO-PEO triblock copolymers was studied by surface tension measurement, UV-vis spectra, and surface pressure method. These results clearly showed that the CMC of PEO-PPO-PEO was not a certain value but a concentration range, in contrast to classical surfactant, and two breaks around CMC were reflected in both surface tension isotherm curves and UV-vis absorption spectra. The range of CMC became wider with increasing PPO/PEO composition ratio. Surface pressure Pi-A curves revealed that the amphiphilic triblock copolymer PEO-PPO-PEO molecule was flexible at the air/water interface. We found that the minimum area per molecule at the air/water interface increased with the proportion of PEO chains. The copolymers with the same mass fractions of PEO had similar slopes in the isotherm of the Pi-A curve. From the demulsification experiments a conclusion had been drawn that the dehydration speed increased with decreased content of PEO, but the final dehydration rate of four demulsifiers was approximate. We determined that the coalescence of water drops resulted in the breaking of crude oil emulsions from the micrograph.     

Surface properties and doxorubicin delivery in mixed systems comprising a natural rosin-based ester tertiary amine and an anionic surfactant

A rosin-based ester tertiary amine salt (RETAS) cationic surfactant was obtained using natural rosin as raw material. GC-MS of RETAS was detailed analyzed. The pH-responsive mechanism of rosin-based ester tertiary amine (RETA) and RETAS was confirmed by applying theoretical calculations about electrostatic potential maps of RETA and RETAS cation using Gaussian software. Mixed system surfactants were obtained by blending RETAS cationic surfactant with sodium dodecyl benzene sulfonate (SDBS) anionic surfactant. The binary mixed surfactant systems of RETAS and SDBS had obvious synergistic effect. The γ_cmc and CMC were 39.40?mN/m and 0.56?mmol/L at the optimum molar fraction of RETAS (α)?=?0.6, respectively. The stability time of emulsion with the optimum mixed system as emulsifier increased to 309?s at α?=?0.6. The emulsifying capacity of RETAS was much better than that of RETA. RETAS had pH-responsive targeted release and the optimum mixed system showed a relatively sustained drug release by using doxorubicin (DOX) as a model drug. These results indicate that RETAS surfactant and mixed system surfactant are both promising for applications in drug delivery and emulsification.