Structure microemulsions

Friberg S E and Liang Y-C 1987 Nonaqueous microemulsions Microemulsions Structure and Dynamics ed S E Friberg and Bothorel (Booa Raton, FL Chemioal Rubber Company) pp 79-91... 

Friberg S E and Bothorei P (eds) 1987 Microemulsions Structure and Dynamics (Boca Raton, FL Chemicai Rubber Company)... 

S. E. Ftiberg and P. Bothorel, Microemulsions Structure and Dynamics, CRC Press, Boca Raton, Fla., 1987. 

Solubilization of biomolecules could induce change in the microemulsion structure. For example, in the presence of the human serum albumin and at low R value, the ternary microemulsion AOT/water/isoctane shows a transition to a bicontinuous microstructure [172],... 

Maidment LJ, Chen V, Warr GG (1997) Effect of added cosurfactant on ternary microemulsion structure and dynamics. Colloids Simf A 130 311-319... 

Figures 7, 8 and 9 are plots at 25 C of specific conductance and density versus volume fraction of methanol in 2/1 triolein/ surfactant systems which are 4/1 molar ratios of 2-octanol to bis(2-ethylhexyl) sodium sulfosuccinate, triethylammonium linoleate and tetradecyldimethylammonium linoleate, respectively. For each surfactant system, a maximum for specific conductance and a minimum for density was observed at the same volume fraction, but this volume fraction of methanol varied between the three surfactant systems. At volume fractions of methanol above these abrupt changes, each system exhibited translucence, and it appears that gel-like structures form. These data are consistent for microemulsion structures that are based largely on geometric considerations (16-18).

Fribeig, S. E. Bothorel, P. Microemulsions Structure and Dynamics CRC Press Boca Raton, FL, 1987. 

Figure 7. The percolation behavior in AOT-water-decane microemulsion (17.5 21.3 61.2 vol%) is manifested by the temperature dependences of the static dielectric permittivity es (A left axis) and conductivity r (Q right axis). Toa is the temperature of the percolation onset Tp is the temperature of the percolation threshold. Insets are schematic presentations of the microemulsion structure far below percolation and at the percolation onset. (Reproduced with permission from Ref. 149. Copyright 1998, Elsevier Science B.V.)...

Ceglie, A., Das, K. P, and Lindman, B. (1987), Microemulsion structure in four component systems for different surfactants, Coll. Surf, 28,29 40. 

Zana R, Lang J (1987) In Frieberg SE, Bothorel (eds) Microemulsions structure and dynamics. CRC, Boca Raton, FL, Ch 6... 

STXM and SPM showed that bicontinuous microemulsion structure with well-defined wave vector has been formed, indicating that the interfacial ten-... 

Fig. 5 shows a hypothetical phase diagram with representation of microemulsion structures. At high water concentrations, microemulsions consist of small oil droplets dispersed in water (o/w microemulsion), while at lower water concentrations the situation is reversed and the system consists of water droplets dispersed in oil (w/o microemulsions). In each phase, the oil and water droplets are separated by a surfactant-rich film. In systems containing comparable amounts of oil and water, equilibrium bicontinuous structures in which the oil and the water domains interpenetrate in a more complicated manner are formed. In this region, infinite curved channels of both the oil and the water domains extend over macroscopic distances and the surfactant forms an interface of rapidly... 

Figure 7.18 Diagrammatic representation of microemulsion structures (a) a water-in-oil microemulsion droplet (b) an oil-in-water microemulsion droplet and (c) an irregular bicontinuous structure.

Figure 4. Idealized AOT reverse micelle or microemulsion structure and a proposed aggregation (or clustering) mechanism which maintains the distinct solvent environments for the reverse micelle conqponents.

The behavior of water in oil microemulsions has been studied using different techniques light scattering, electrical conductivity, viscosity, transient electrical birefringence, ultrasonic absorption. All these experiments lead us to propose a picture of the microemulsions structure which assignes an important role to the fluidity of the interfacial region. 

Microemulsions are transparent fluid mixtures of water, oil, surfactant and cosurfactant (alcohols). At small water fraction, w/o microemulsions are dispersions of water droplets surrounded by a surfactant layer in a continuous oil phase. The microemulsion structure at larger water fraction has been studied with different techniques and some results are presented subsequently. A qualitative microemulsion picture is proposed to explain the data. 

The preceding analysis assigns an important role to the interaction between droplets or equivalently the fluidity of the interfacial region in the microemulsions structure. 

Close to the boundaries Sj and S2 in the three phase domain, the interfacial tensions were found to be very low. In that case, the theoretical model presented above is no longer valid, first of all because the middle phase microemulsion structure is not simply a droplet dispersion. Furthermore the interaction term F becomes evidently dominant and is difficult to evaluate since the nature of the forces is not perfectly known. However, such low interfacial tensions are characteristic of critical consolute points. It was then tempting to check that the behavior of the interfacial tensions was compatible with the universal scaling laws obtained in the theory of critical phenomena. In these theories the relevant parameter is the distance e to the critical point defined by ... 

Effect of Microemulsion Structure on the Transport Properties. It appears from the discussion above that the reduction in the ionic conductivity and water self-diffusion coefficient is primarily attributable to hydration effects, not principally to changes in the structure of the microemulsion with higher phase volume. 

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