Gemini表面活性剂的吸附、自聚和性质

Gemini表面活性剂通常是由两 (或三 )条疏水链、两个亲水基和一个连接基组成的两性分(离 )子 ,与由单亲水基和单疏水基构成的单体表面活性剂分 (离 )子相比较 ,在临界胶团浓度、界面性质和溶解性等方面有着独特的性质。由于其电荷密度高 ,临界胶团浓度低 ,并且有很低的 Krafft点 ,能在低浓度下与高碳烷烃形成超低界面张力 ,在石油开发中有着很好的应用前景。详述了该类新型表活性剂的吸附、自聚、性质 ,比较了与单体表面活性剂的差别     

表面活性剂

表面活性剂是一种能吸附在两相界面,从而改变相界面性质的物质,例如表面活性剂吸附在固液界面能降低表面张力,使固体表面的润湿性增强。     

Gemini表面活性剂的性质研究

Gemini表面活性剂通常是由两（或三）条疏水链、两个亲水基和一个连接基组成的两性分（离）子,与由单亲水基和单疏水链构成的传统表面活性剂分（离）子相比较,在临界胶团浓度、界面性质等方面有着独特的性质。详述了该类新型表面活性剂的性质,比较了与传统表面活性剂的差别。     

居贝特醇十六烷基醚羟丙基季铵盐及其复配体系在石英表面吸附的研究

利用座滴法研究了阳离子表面活性剂居贝特醇十六烷基醚羟丙基季铵盐(C16GPC)溶液在石英表面上的润湿性能,并考察了非离子表面活性剂辛基酚聚氧乙烯醚(Triton X-100)及不同类型电解质对其接触角的影响趋势。研究发现,C16GPC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cmc附近形成双层结构,接触角随浓度变化的趋势存在一个极大值;Triton X-100与C16GPC在界面上混合吸附,进一步降低表面张力,且影响固/液界面膜排列的规整性,从而造成接触角明显降低;电解质促进表面活性剂在气/液界面的吸附,同时抑制其在固/液界面的吸附,共同导致接触角降低。     

阴离子型Gemini表面活性剂的合成及性能研究进展

综述了一系列阴离子型Gemini表面活性剂(包括磺酸盐型、硫酸酯盐型、羧酸盐型及磷酸酯盐型)的合成方法,并介绍了其表面活性、水溶性、协同效应、增溶作用、抗盐能力等理化性能,对今后阴离子型Gemini表面活性剂的研究提出了一些看法.     

Gemini表面活性剂在不同状态下的自组装行为研究进展

自Gemini表面活性剂报道以来,受到了研究者和工业界的广泛关注。对于其结构设计、性能研究、工业应用的报道层出不穷。本文综述了Gemini表面活性剂在不同状态下的自组装行为,主要包括水溶液中的自组装、气液界面上的Langmuir单分子膜、离子液晶及气液界面上的晶体生长。分析和展望了今后Gemini表面活性剂自组装体系的研究方向。     

Gemini（孪联）表面活性剂的界面性质与应用

全面地评述Gemini(孪联）表面活性剂在界面吸附,不溶膜和协同效应等方面近两年国际上的研究进展,总结了部分有代表性Gemini(孪联）表面活性剂的界面物理化学性质。并介绍了这类表面活性剂在增溶,乳液聚合,抗菌和新材料制备等领域的优良应用性能。     

表面活性剂的性能与应用(Ⅹ)——表面活性剂的吸附作用及其应用

重点阐述了表面活性剂在气/液、液/液和固/液界面上的吸附机理以及吸附特点,并分别分析了表面活性剂在上述3种界面上吸附作用的影响因素。最后介绍了表面活性剂的吸附作用在几种应用领域的研究进展。     

vGemini表面活性剂的聚集行为及应用的新进展

综述了已报道的几种新型Gemini表面活性剂的化学结构，并对它们在气／液、气／固界面及溶液中的聚集行为和应用做了讨论。     

Gemini表面活性剂的性能及应用

Gemini表面活性剂是一类新型的表面活性剂,它是由联结基团通过化学键将两个或多个单体表面活性剂连接在一起而形成。综述了Gemini表面活性剂结构特征与性能(包括界面吸附、表面活性、临界胶束浓度和协同效应等),并就它在助染、新材料制备、药物、驱油、环境保护、生物技术和抗病毒等方面的应用作了介绍。     

Ethoxy Carboxylate Extended Surfactant: Micellar,Adsorption and Adsolubilization Properties

The micellar, adsorption, and adsolubilization properties of a novel ethoxy carboxylate extended surfactant are measured and compared to an extended sulfate surfactant. The critical micelle concentration (CMC) of the ethoxy carboxylate extended surfactant is measured to be 0.02 mM while it is 0.07 mM for the extended sulfate surfactant. Adsorption and adsolubilization studies are carried out on alumina oxide surfaces. The extended sulfate surfactant has a higher maximum adsorption capacity onto the aluminum than the ethoxy carboxylate extended surfactant (0.47 vs. 0.14 mmol/g, respectively). For adsolubilization, the extended sulfate surfactant shows a slightly higher phenanthrene adsolubilization compared to the ethoxy carboxylate extended surfactant (log K_adm of 6.15 vs. 5.71, respectively). In contrast, for solubilization, the ethoxy carboxylate extended surfactant exhibits higher phenanthrene solubilization capacities than the extended sulfate surfactant (log K_mic of 5.61 vs. 5.42, respectively). Relative to surfactant loss from the solid surface, the ethoxy carboxylate extended surfactant shows a higher desorption capacity as compared to the extended sulfate surfactant. From these measurements, the ethoxy carboxylate extended surfactant has better properties for micellar applications (lower CMC, higher K_mic), while the extended sulfate surfactant has better properties for admicellar applications (higher q_max and K_adm values, and less desorption).     

Solubilization and Adsolubilization of Polar and Nonpolar Organic Solutes by Linker Molecules and Extended Surfactants

Adsolubilization reaches its maximum when a surfactant adsorbed onto the solid–liquid interface achieves complete bilayer or maximum adsorption. The attempt to enhance the adsolubilization of organic solute is accomplished by increasing interaction between the hydrophobic core of adsorbed admicelles and the organic solute. Solubilization and adsolubilization were studied with linker-based and extended-surfactant-based systems. Extended surfactants have propylene oxide (PO) groups of intermediate polarity inserted between hydrophobic and lipophilic moieties in the surfactant molecule. This study evaluated the adsolubilization of polar (phenylethanol) and nonpolar (ethylcyclohexane) solutes into conventional linker-based and extended-surfactant-based admicelles. The results demonstrated that the extended-surfactant-based systems showed higher solubilization capacity than the conventional sodium dodecyl sulfate alone or with linker. For the polar solute, the presence of PO group has a greater effect than the number of PO groups or the tail length, while for the nonpolar solute as the number of POs groups and the tail length increased, the adsolubilization capacity also increased. Preliminary explanations for these observations are provided.

Effect of Ionic Head Group on Admicelle Formation by Polymerizable Surfactants

One of the problems of using surfactant-modified adsorbents in a surfactant-based adsorption process is loss of surfactant because of desorption. Recently, polymerizable surfactants have been used to minimize surfactant losses by polymerization of the surfactant admicellar structure to help secure it to the solid oxide surface. In this study, adsorption of polymerizable cationic gemini surfactant was used to form polymerized bilayers on silica. UV light was used to irradiate and initiate the polymerization process. Surfactant adsorption and desorption were evaluated to compare the efficiency of polymerized and non-polymerized surfactants using gemini and conventional surfactants, respectively. Results demonstrate that the increased stability of the polymerized surfactant-modified surface can reduce the desorption of surfactant from the surface, thereby improving operating characteristics of the surfactant-modified media (e.g., maintaining adsolubilization potential, dispersion stability, etc.).     

Molecular dynamics simulation on the structure–activity relationship between the Gemini surfactant and foam properties

The structure–activity relationship between the molecular structure of Gemini surfactants and foam properties has not yet been deeply revealed. In this study, we clarified for the first time the structure–activity relationship between foam properties and molecular structure of Gemini surfactant by discussing the variation characteristics of parameters such as free energy of interface formation, radial distribution function, and mean square displacement calculated by molecular simulation method. The research results show that (1) the Gemini surfactant with the sulfonic acid head group has the most excellent foam properties; (2) the foam properties increase monotonously with the increase of the hydrophobic tail chain length; (3) the foam properties decrease monotonously with the increase of the spacer group length. It is hoped that this article can further broaden the application range of surfactants as foaming agents in industrial fields such as oil and gas exploitation.     

流体在固体表面超铺展特性的研究进展

对流体在固体表面超铺展特性的研究进展进行了综述,总结了具有超铺展特性的动态湿润体系、超铺展特性的影响因素、内在机理以及实验关联式建立和数值模拟方法。部分丙硅氧烷类和烷基乙氧基化物类以及少数离子型表面活性剂溶液具有超铺展特性,浓度和固体表面能是超铺展的重要影响因素。气液界面的浓度Marangoni效应被认为是超铺展过程的控制因素,表面活性剂在气液、固液和三相接触线前缘固气界面的输运和吸附对浓度Marangoni效应有重要影响。分析认为,实验方面未来应拓展实验体系,建立超铺展产生的判据;深入研究宏观影响因素以及微观输运和吸附机理,同时考虑外加物理场影响,为超铺展的实际应用奠定基础。理论方面需综合考虑表面活性剂向界面的输运、吸附对界面性质的作用规律以及浓度Marangoni效应的影响,借鉴相对成熟的牛顿流体动态湿润理论,建立描述超铺展特性的全过程理论模型。数值模拟方面应以分子动力学模拟为基础建立表面活性剂输运和界面吸附的微观物理模型,将其引入流体动力学模型,实现对超铺展过程精确定量化的描述。本文还给出了可能的超铺展体系铺展全过程的物理图景。     

Adsorption of cationic monomeric and gemini surfactants on montmorillonite and adsolubilization of vitamin E

Adsorption of a cationic gemini surfactant (1,2-bis(dodecyldimethylammonio) ethane dibromide, 12-2-12) and the corresponding monomeric surfactant (dodecyltrimethylammonium bromide, DTAB) on montmorillonite has been characterized with a combination of adsorption isotherm, interlayer spacing and FT-IR spectroscopic data. Adsolubilization of vitamin E into the adsorbed surfactant layers has also been studied. The adsorption isotherm data reveal that the adsorption of the two surfactants is driven by the two factors: one is the cation exchange that occurs on the interlayer basal planes and the other is the hydrophobic interaction between hydrocarbon chains of the surfactants. Although the adsorbed amount measured in the saturation region (in mol g(-1)) is almost identical for the two surfactants, the conformation of the intercalated surfactant molecules differs significantly from each other. The adsorption of DTAB results in a lateral bilayer arrangement in the limited interlayer space, whereas 12-2-12 gives a normal bilayer arrangement in the expanded interlayer space. Adsolubilization of vitamin E takes place into the adsorbed surfactant layers, and interestingly, all the vitamin E molecules added in the montmorillonite suspensions are hybridized at lower surfactant concentrations due to the great specific surface area of the clay material. Since the maximum adsolubilization amount is usually obtained just below the critical micelle concentration, the gemini surfactant is deemed to be more efficient than the corresponding monomeric one to achieve the great adsolubilization amount.     

离子液体表面活性剂的合成与应用(I)——离子液体表面活性剂的结构和分类

在介绍了离子液体的结构特点和特性的基础上,重点综述了离子液体表面活性剂的结构特征,并且按阳离子型、阴离子型、两性型、双子型和Bola型五类分别介绍了离子液体表面活性剂的典型结构和文献发表的主要品种,显示了离子液体表面活性剂具有较强的结构可设计性和未来品种的多样性。     

Interfacial Dynamic Properties and Dilational Rheology of Sulfonate Gemini Surfactant and its Mixtures with Quaternary Ammonium Bromides at the Air–Water Interface

The dynamic interfacial properties and dilational rheology of gemini sulfonate surfactant (SGS) and its mixtures with quaternary ammonium bromides (DTAB, CTAB) at the air–water interface were investigated using drop shape analysis. Results suggest that the adsorption process of these surfactants is diffusion-controlled at dilute concentrations, whereas the adsorption mechanism gradually shifts to a mixed kinetic-diffusion control with increasing surfactant concentration. The mixed surfactant system possesses the best surface activity when the molar ratios of SGS/DTAB and SGS/CTAB mixtures are 9:10. The formation of catanionic complexes shields the electrostatic repulsion between surfactant molecules and lowers the electrostatic adsorption barrier. Therefore, SGS/DTAB and SGS/CTAB mixtures exhibit higher adsorption rates than either component alone. The effects of oscillating frequency and surfactant concentration on the surface dilational properties of SGS, DTAB, CTAB, SGS/DTAB, and SGS/CTAB mixtures were also determined. As the oscillating frequency increases, the dilational elasticity of these surfactants gradually increases. The dilational elasticity peaks at a certain concentration, which is less than the critical micelle concentration (CMC). Results show that the dilational elasticity of SGS/DTAB and SGS/CTAB mixtures is higher than that of either component, resulting from the formation of a denser monomolecular adsorption layer at the air–water interface. Our study provides a basis for understanding the interaction mechanism of catanionic surfactant mixtures containing Gemini surfactant at the air–water interface.