Aerosol-OT microemulsions

P. E. Zinsli, Inhomogeneous interior of aerosol OT microemulsions probed by fluorescence and polarization decay,/. Phys. Chem. 83, 3223-3231 (1979). 

Changez, M. and Varshney, M. (2000) Aerosol-OT microemulsions as transdermal carriers of tetracaine hydrochloride. Drug Dev. Ind. Pharm., 26, 507-512. 

Junyaprasert VB, Boonme P, Wurster DE, and Rades T. (2008). Aerosol OT microemulsions as carriers for transdermal delivery of hydrophobic and hydrophilic local anesthetics. Drug Delivery, 15, 323-330. 

Vanag, V.K., Epstein, I.R. Pattern formation in a tunable medium the Belousov-Zhabotinsky reaction in an aerosol-OT microemulsion. Phys. Rev. Lett. 87, 228301 (2001)... 

Cationic surfactants may be used [94] and the effect of salinity and valence of electrolyte on charged systems has been investigated [95-98]. The phospholipid lecithin can also produce microemulsions when combined with an alcohol cosolvent [99]. Microemulsions formed with a double-tailed surfactant such as Aerosol OT (AOT) do not require a cosurfactant for stability (see, for instance. Refs. 100, 101). Morphological hysteresis has been observed in the inversion process and the formation of stable mixtures of microemulsion indicated [102]. 

Zulauf M and Eicke FI 1979 Inverted micelles and microemulsions in the ternary system Fl20/aerosol-OT-isoctane as studied by photon correlation spectroscopy J. Phys. Chem. 83 480... 

Figure 1. Anionic surfactant aerosol OT for a microemulsion preparation.

Zulauf, M and Eicke, H.F. "Inverted Micelles and Microemulsions in the Ternary System H20/Aerosol OT/Isooctane as Studied by Photon Correlation Spectroscopy," J. Phvs. Chem.. 1979, 82(4), 480 486. 

Arriagada, F.J., and Osseo-Asare, K. (1995) Synthesis of nanosize silica in aerosol OT reverse microemulsions./. Colloid Interface Sci. 170, 8-17. 

Figure 12.15. Fluorescence lifetime of IR-140 in Aerosol OT (AOT)/iso-octane microemulsions as a function of water pool size to, defined as the molar fraction of water to AOT. (From Ref. 58.)...

On the other hand, with microemulsions based on an anionic surfactant and a long chain alcohol, was fairly low for certain concentrations, indicating that distinct water droplets in a hydrophobic medium may form. The system investigated by Lindman et al (29-34) was based on octanoic acid - decanol -octane-water. This means that the anionic "surfactant" used contains only seven carbon atoms in the alkyl chain which is fairly short. With longer chain surfactants, one would expect well defined "water cores" provided the alcohol is also long-chain. Such well defined "water cores" have also been confirmed by Lindman et a (34) for the Aerosol OT - hydrocarbon system. 

Lopez-Quintela MA (2003) Synthesis of nanomaterials in microemulsions formation mechanisms and growth control. Curr Opin Colloid Interface Sci 8 137-144 Lopez-Quintela MA, Tojo C, Blanco MC, Rio LG, Leis JR (2004) Microemulsion dynamics and reactions in microemulsions. Curr Opin Colloid Interface Sci 9 264-278 Maitra A (1984) Determination of Size Parameters of Water Aerosol Ot Oil Reverse Micelles from Their Nuclear Magnetic-Resonance Data. J Phys Chem 88 5122-5125... 

Robinson BH, Toprakcioglu C, Dore JC, Chieux P (1984) Small-Angle Neutron-Scattering Study of Microemulsions Stabilized by Aerosol-Ot.l. Solvent and Concentration Variation. J Chem Soc Faraday Trans 1 80 13-27... 

Arriagada FJ, Osseoasare K (1994) Silica Nanoparticles Produced in Aerosol Ot Reverse Microemulsions - Effect of Benzyl Alcohol on Particle-Size and Polydispersity. J Dispers Sci Technol 15 59-71... 

Zulauf M, Eicke HE (1979) Inverted Micelles and Microemulsions in the Ternary-System H2o-Aerosol-Ot-lsooctane as Studied hy Photon Correlation Spectroscopy. 

Towey TF, Khanlodhi A, Robinson BH (1990) Kinetics and Mechanism of Formation of Quantiun-Sized Cadmium-Sulfide Particles in Water Aerosol-Ot Oil Microemulsions. J Chem Soc Faraday Trans 86 3757-3762... 

ForCaCO, particles in W/O microemulsions of hexaethylene glycol dodecyl ether, however, the values of Nm/Np lie between 0.044 and 0.28, indicating that the particles form by the destruction of micelle-solubilizing aqueous Ca(OH)2 rather than by the intermicellar exchange process (5). In the case of the formation of CaCO-) particles in the Ca salt of Aerosol OT-cyclohexane system, as seen in Table 7.2.2, the particles... 

Holmes et al. (1998) performed two enzymatic reactions, the lipase-catalyzed hydrolysis of y>-nitrophenol butyrate and lipoxygenase-catalyzed peroxidation of linoleic acid, in w/c microemulsions stabilized by a fluorinated two-chained sulfosuccinate surfactant (di-HCF4). The activity of both enzymes in the w/c microemulsion environment was found to be essentially equivalent to that in a water/heptane microemulsion stabilized by Aerosol OT, a surfactant with the same headgroup as di-HCF4. The buffer 2-(A-morpholino)ethanesulfonic acid (MES) was used to fix the pH in the range 5-6. 

The ultralow interfacial tension can be produced by using a combination of two surfactants, one predominantly water soluble (such as sodium dodecyl sulfate) and the other predominantly oil soluble (such as a medium-chain alcohol, e.g., pentanol or hexanol). In some cases, one surfactant may be sufficient to produce the microemulsion, e.g., Aerosol OT (dioctyl sulfosuccinate), which can produce a W/O microemulsions. Nonionic surfactants, such as alcohol ethoxylates, can also produce O/W microemulsions, within a narrow temperature range. As the temperature of the system increases, the interfacial tension decreases, reaching a very low value near the phase inversion temperature. At such temperatures, an O/W microemulsion may be produced. 

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