Interaction of Anionic Gemini Surfactants with Other Surfactants

The interaction of anionic gemini surfactants with other surfactants (such as anionic, cationic, nonionic) was systematically overviewed, paying attention to synergism observed in various properties. These mixed systems were found to show remarkable synergism in micelle formation. The critical micelle formation values being lower than the individual gemini surfactants indicate that the mixed micellization is due to attractive interaction between the two components. Almost all combinations were discussed in terms of respective surface tension reduction effectiveness and surface tension reduction efficiency and aggregation number for evaluation of synergism.     

Gemini Surfactants

How easy it is to dismiss the humdrum surfactant! After all, its structure is unglamorous by present-day norms. And the surfactant has been entrenched in so many areas of commerce for so many decades that its chemistry might seem old and tired. The purpose of this review is to persuade the reader otherwise, all the while focusing on a remarkable new surfactant, the gemini. Geminis, the common name for "bis-surfactants", can self-assemble at concentrations almost a hundredfold lower than for corresponding conventional surfactants. Surface activity can be improved a thousandfold. Geminis have already shown promise in skin care, antibacterial regimens, construction of high-porosity materials, analytical separations, and solubilization processes. Scores of patents dealing with geminis have appeared in the last few years. Indeed, geminis might well turn out, in the opinion of some, to be more useful to "l'homme de la rue" than crown ethers or fullerenes. This review delves into such topics as synthesis, critical micellization concentration, aggregate size and shape, gels, vesicles, and films. The information comes from scientists all over the world; one might say that gemini research is bathed in a continuous sunlight or summer. No prior knowledge of colloid chemistry is presupposed in this article.     

环境刺激响应型表面活性剂

表面活性剂在溶液中可通过自组装形成胶束、囊泡、液晶等多种有序结构。这些有序自组装结构在催化化学、材料制备、生物医药等领域有着重要而广泛的用途。控制和改变表面活性剂在溶液中的聚集方式对表面活性剂的应用具有重要的意义。近年来,通过对外界环境的调控来改变表面活性剂的物理化学性能如表面张力、聚集形式等研究已成为表面活性剂研究的一个新方向。本文以外界环境变化对表面活性剂在溶液中的聚集方式的影响为基础,介绍了可对环境刺激产生响应的表面活性剂的种类、结构、性能及研究进展,并总结了它们的结构与环境刺激响应性能之间的关系。     

天然高分子表面活性剂

综述了淀粉、纤维素和壳聚糖类表面活性剂的合成方法、性质及功能。     

Mixed Micellization of Dimeric (Gemini) Surfactants and Conventional Surfactants

The aqueous solutions of mixtures of various conventional surfactants and dimeric anionic and cationic surfactants have been investigated by electrical conductivity, spectrofluorometry, and time-resolved fluorescence quenching to determine the critical micelle concentrations and the micelle aggregation numbers in these mixtures. The following systems have been investigated: 12-2-12/DTAB, 12-2-12/C(12)E(6), 12-2-12/C(12)E(8), 12-3-12/C(12)E(8), Dim3/C(12)E(8), and Dim4/C(12)E(8) (12-2-12 and 12-3-12=dimethylene-1,2- and trimethylene-1,3-bis(dodecyldimethylammonium bromide), respectively; C(12)E(6) and C(12)E(8)=hexa- and octaethyleneglycol monododecylethers, respectively; Dim3 and Dim4=anionic dimeric surfactants of the disodium sulfonate type, Scheme 1; DTAB=dodecyltrimethylammonium bromide). For the sake of comparison the conventional surfactant mixtures DTAB/C(12)E(8) and SDS/C(12)E(8) (SDS=sodium dodecylsulfate) have also been investigated (reference systems). Synergism in micelle formation (presence of a minimum in the cmc vs composition plot) has been observed for the Dim4/C(12)E(8) mixture but not for other dimeric surfactant/nonionic surfactant mixtures investigated. The aggregation numbers of the mixed reference systems DTAB/C(12)E(8) and SDS/C(12)E(8) vary monotonously with composition from the value of the aggregation number of the pure C(12)E(8) to that of the pure ionic component. In contrast, the aggregation number of the dimeric surfactant/C(12)E(8) mixtures goes through a minimum at a low value of the dimeric surfactant mole fraction. This minimum does not appear to be correlated to the existence of synergism in micelle formation. The initial decrease of the aggregation number of the nonionic surfactant upon addition of ionic surfactant, up to a mole fraction of ionic surfactant of about 0.2 (in equivalent per total equivalent), depends little on the nature the surfactant, whether conventional or dimeric. The results also show that the microviscosity of the systems containing dimeric surfactants is larger than that of the reference systems. Copyright 2001 Academic Press.     

日常生活与表面活性剂

本文介绍了表面活性剂在日常生活中的应用,并介绍了它的分类、结构特点、洗涤原理以及今后的发展趋势。     

Activity of Nonionic Surfactants

The surface activity of block copolymers of ethylene and propylene oxides, based on ethylenediamine, mono(ethylene glycol), and triethanolamine, was studied. Adsorption characteristics of the investigated compounds at the water-air interface are estimated.     

Surfactants for CO2

For some 15 years the attainment of efficient, nonfluorinated CO2-active surfactants has been a Holy Grail for researchers spanning pure and applied chemical sciences. This article tells the story of small-molecule CO2-active surfactants, from the first tentative observations with fluorinated compounds in 1991 up to recently discovered fluorine-free oxygenated amphiphiles.     

Surfactants in Thin-Layer Chromatography

Data reported in the literature on the use of surfactants as modifiers of mobile and stationary phases in thin-layer chromatography are analyzed. The features of micellar and ion-pair versions of thin-layer chromatography and the dynamic and static modifications of stationary phases with surfactants are considered.     

Surfactants in droplet-based microfluidics

Surfactants are an essential part of the droplet-based microfluidic technology. They are involved in the stabilization of droplet interfaces, in the biocompatibility of the system and in the process of molecular exchange between droplets. The recent progress in the applications of droplet-based microfluidics has been made possible by the development of new molecules and their characterizations. In this review, the role of the surfactant in droplet-based microfluidics is discussed with an emphasis on the new molecules developed specifically to overcome the limitations of 'standard' surfactants. Emulsion properties and interfacial rheology of surfactant-laden layers strongly determine the overall capabilities of the technology. Dynamic properties of droplets, interfaces and emulsions are therefore very important to be characterized, understood and controlled. In this respect, microfluidic systems themselves appear to be very powerful tools for the study of surfactant dynamics at the time- and length-scale relevant to the corresponding microfluidic applications. More generally, microfluidic systems are becoming a new type of experimental platform for the study of the dynamics of interfaces in complex systems.     

杂双子表面活性剂的研究进展

分子结构对称的gemini 表面活性剂是通过联接链将两个相同头基和相同烷烃链的普通表面活性剂在头基或靠近头基处以化学键方式联接在一起,这种表面活性剂产生了新颖且复杂的自组织行为,引起人们的高度关注。但由于合成上的困难,迄今为止较少研究分子结构不对称的gemini 表面活性剂(又称为杂双子表面活性剂,heterogemini surfactant) 。初步研究显示heterogeminis 在分子自组织过程中具有更多可调控的分子结构因素,获得了某些新颖的结果,例如明显增大了自组织过程的焓驱动力,正-负离子头基分子构成了无反离子的体系,长-短烷烃主链分子成功地将形成的囊泡串接起来等。本文综述当前的研究进展,并提出某些潜在的研究意义。     

杂双子表面活性剂的合成

α-溴代十四酸甲酯与对甲苯酚经W illiam son醚化、NBS溴化、季铵化、皂化得3个头基分别是羧酸盐和季铵盐的杂双子表面活性剂,其结构经1HNMR,IR和元素分析确认。     

铵基乙酸盐型两性表面活性剂的合成

以月桂酸、硬酯酸和羟乙基乙二胺为原料，经环化、还原和季铵化合成了４种新化合物，对其中２种按基乙酸盐两性表面活性剂的表面张力、临界胶束浓度（ｃｍｃ）和泡沫性能做了测定。     

Capillary Electrophoresis of Cationic Surfactants

Surfactants are important additives in many chemical processes and products. A wide range of surfactants exists, including anionic, cationic, nonionic and zwitterionic. Benzalkonium chloride (BAC) is a widely used cationic surfactant in pharmaceutical and health-care products since it possesses antiseptic and antibacterial properties.     

一类活性极高的高分子表面活性剂

一类活性极高的高分子表面活性剂范仲勇，李娜，吴大诚（四川联合大学轻纺学院，成都，６１００６５）ＺｈａｏｈｕｉＳｕ，Ｓ．Ｌ．Ｈｓｕ（ＤｅｐａｒｔｍｅｎｔｏｆｐｏｌｙｍｅｒＳｃｉｅｎｃｅ＆Ｅｎｇｉｎｅｅｒｉｎｇ，ＵｎｉｖｅｒｓｉｔｙｏｆＭａｓｓａｃｈｕｓ...     

高分子表面活性剂的合成

介绍了高分子表面活性剂的合成方法及其不同于低分子表面活性剂的特点,重点从离子聚合、活性自由基聚合、缩合聚合、开环聚合、高分子化学反应、自由基胶束聚合等角度综述了近几-来高分子表面活性剂的合成研究进展.     

表面活性剂的提纯与鉴定

简要综述了迄今使用表面活性剂纯化及鉴定方法,重点介绍了近几年以来的进展。     

Polymerisable Surfactants in Miniemulsion Polymerisation

Stable miniemulsions of styrene or methyl methacrylate (MMA) were prepared in the presence of hexadecane and a styrenic polymerisable surfactant, the vinylbenzylsulfosuccinic acid sodium salt (VBSS). They were polymerised to high conversion, using potassium persulfate (KPS) or 2,2′‐azoisobutyronitrile (AIBN) with no significant change in the particle size during reaction. The stability of the latexes was excellent when KPS was used, and the reasons for this are discussed. The size of the particles was further increased by using these latexes as a seed, and feeding a continuous stream of monomer in the presence of another polymerisable nonionic surfactant.