Phase behavior, of surfactants

R. G. Laughlin, The Aqueous Phase Behavior of Surfactants, Academic, London, 1994. 

R. G. Larson. Monte Carlo simulations of the phase behavior of surfactant solutions. J Phys II Erance 6 1441-1463, 1996. 

Laughlin RG (1994) The aqueous phase behavior of surfactants. Academic, London... 

Wade WH, Morgan J, Schechter RS, Jacobson JK, Salager JL (1978) Interfacial tension and phase behavior of surfactant systems. Soc Petrol Eng J 18 242... 

Salager JL, Marquez N, Anton RE, Graciaa A, Lachaise J (1995) Retrograde Transition in the Phase Behavior of Surfactant-oil-water systems produced by an alcohol scan. Langmuir 11 37-41... 

Ysambertt F, Anton RE, Salager JL (1997) Retrograde Transition in the phase behavior of surfactant-oil-water systems produced by an oil EACN scan. Colloid Surf A 125 131-136... 

It is well known that the aqueous phase behavior of surfactants is influenced by, for example, the presence of short-chain alcohols [66,78]. These co-surfactants increase the effective value of the packing parameter [67,79] due to a decrease in the area per head group and therefore favor the formation of structures with a lower curvature. It was found that organic dyes such as thymol blue, dimidiiunbromide and methyl orange that are not soluble in pure supercritical CO2, could be conveniently solubihzed in AOT water-in-C02 reverse microemulsions with 2,2,3,3,4,4,5,5-octafluoro-l-pentanol as a co-surfactant [80]. In a recent report [81] the solubilization capacity of water in a Tx-lOO/cyclohexane/water system was foimd to be influenced by the compressed gases, which worked as a co-surfactant. 

Finally, it should be mentioned that a combination of COSMO-RS with tools such as MESODYN [127] or DPD [128] (dissipative particle dynamics) may lead to further progress in the area of the mesoscale modeling of inhomogeneous systems. Such tools are used in academia and industry in order to explore the complexity of the phase behavior of surfactant systems and amphiphilic block-co-polymers. In their coarse-grained 3D description of the long-chain molecules the tools require a thermodynamic kernel... 

This review obviously reflects the preferences of the author in stressing the application of FT - IR to amphiphile phase behavior and the kinetics of interfacial phenomena. In some sense, FT - IR may be considered an emerging technique in studies of the phase behavior of surfactants. However, from the wide range of studies of lipid bilayers mentioned, it seems that the concept of using FT - IR to probe surfactant molecule associative properties in other aggregates such as micelles, gels and vesicles can be considered a logical extension. 

The phase behavior of surfactant systems is particularly complex because of the existence of numerous lyotropic (solvent-induced) liquid crystal phases (3). These phases, like liquids and crystals, are discrete states of matter. They are fluids, but their x-ray patterns display sharp lines signifying the existence of considerable structure. They are often extremely viscous because of their high viscosities and for other reasons they are difficult to study using conventional methods. This is evident from the fact that serious errors in the presumably well-established classical aqueous phase diagrams of soaps, sodium alkyl sulfates, monoglycerides, and... 

A correlation of the detergency performance and the equilibrium phase behavior of such ternary systems is expected, based on the results presented by Miller et al. (3,6). The phase behavior of surfactant - oil - water (brine) systems, particularly with regard to the formation of so-called "middle" or "microemulsion" phases, has been shown by Kahlweit et al. (7,8) to be understandable in teims of the... 

Figure 11, which is based on the phase behavior of surfactant/ oil/water systems, illustrates just a few of the many different patterns of phase behavior that may be encountered. On the left is a simple, "well-behaved" system, such as is implicitly assumed in most mobility control studies on "foams." Barring unforeseen wettability problems, the system can be expected to form a "C02 in-water foam."... 

Reverse micelle and microemulsion solutions are mixtures of a surfactant, a nonpolar fluid and a polar solvent (typically water) which contain organized surfactant assemblies. The properties of a micelle phase in supercritical propane and ethane have been characterized by conductivity, density, and solubility measurements. The phase behavior of surfactant-supercritical fluid solutions is shown to be dependent on pressure, in contrast to liquid systems where pressure has little or no effect. Potential applications of this new class of solvents are discussed. 

An understanding of the phase behavior of surfactant-supercritical fluid solutions may be relevant to developing efficient secondary oil recovery methods because oil displacing fluids, such as a C02/surfactant mixture, may be supercritical at typical well conditions. In addition, the original oil in the well may contain dissolved gases such as ethane, propane, or butane, which may effect the phase behavior of the surfactant solution used to sweep out remaining oil. 

Laughlin RG (1994). The Aqueous Phase Behavior of Surfactants, Academic Press, New York. Lequeux F, Candau SJ (1997). In Theoretical Challenges in the Dynamics of Complex Fluids, McLeish TCB (ed), NATO ASI Series E Applied Sciences, Vol 339, Kluwer, London, p 181. Linemann R, Lauger J, Schmidt G, Kratzat K, Richtering W (1995). Rheol Acta 34 440. 

The phase behavior of surfactant formulations for enhanced oil recovery is also affected by the oil solubilization capacity of the mixed micelles of surfactant and alcohol. For low-surfactant systems, the surfactant concentration in oil phase changes considerably near the phase inversion point. The experimental value of partition coefficient is near unity at the phase inversion point (28). The phase inversion also occurs at the partition coefficient near unity in the high-surfactant concentration systems (31). Similar results were also reported by previous investigators (43) for pure alkyl benzene sulfonate systems. 

Jackson (2006) tested the effect of sodium carbonate on the phase behavior of surfactants using a crude oil with little or no acid. He observed that the equilibration is more rapid for the sample containing a higher sodium carbonate concentration, and it also shortened the time required for microemulsion to... 

Martin, E.D., Oxley, J.C., 1985. Effect of various chemicals on phase behavior of surfactant/brine/ oil mixtures. Paper SPE 13575 presented at the International Symposium on Oilfield and Geothermal Chemistry, Phoenix, 9-11 April. 

A book by Laugh in [76] is a very valuable reference on the aqueous phase behavior of surfactants. It covers this vast area of science from the viewpoints of the role of phase science within physical science, physical chemistry (thermodynamics of immiscibility, phase diagrams, the phase rule, characteristic features of surfactant phase behavior, kinetic and mechanistic aspects of surfactant phase behavior, relative humidity), structures and properties of surfactant phases, molecular correlations (surfactant and nonsurfactant behavior in amphiphilic molecules, hydrophilicity, lipophilicity, proximate and remote substituent effects, influence of third components on aqueous surfactant phase behavior), the relationship of the physical science of surfactants to their utility, and the history of surfactant phase science. 

J. L., and Schechter, R. S., "Interfacial Tension and Phase Behavior of Surfactants Systems," Paper SPE 6844, presented at the 52nd Annual Fall Meeting of the SPE, Denver, Colorado, (October 1977). 

The phase behavior of surfactants in water and hydrocarbon is the key to understanding the water- and oil-dissolving power of certain surfactant systems and the interfacial tension between the phases that form in these systems (1, 2). Ultralow tensions less than lOyN/m (0.01 dyn/cm) are required by one of the important mechanisms in various processes for enhancement of petroleum recovery. Much information is now in the literature (3 r4 r5 r6) t but most of the data are for commercial surfactants which are complex mixtures of surface-inactive as well as surface-active components (7 ). ... 

Winsor has reported the relationship between the phase behavior of surfactants, oil, water, and nature of the different components of ternary system. According to Winsor, there are four types of microemulsion phases, which exist in equilibria. These phases are referred to as Winsor phases. They are... 

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