Reverse micelle formation

Jensen, M.R, Yaita, T., Chiarizia, R. 2007. Reverse micelle formation in the partitioning of trivalent f-element cations by biphasic systems containing a tetraalkyldiglycolamide. Langmuir 23 (9) 4765 1774. 

Interactions Give the relative order of strength of interactions (weak, medium, strong) in the following series of pairs in low-polar solvent, dielectric constant e<10 (a) solvent + additive, (b) Calcium benzenesulfonates reverse micelles formation, (c) strong acid (HS) + N-base, (d) weak acid (HA) + N-base, (e) soot particle + reverse micelle, and (f) mechanically activated surface processes and molecular decomposition. 

Table 3.1. Reverse micelle formation in hydrocarbon solvents...

Table II lists the surfactants which exhibited the highest degree of solubility in pentane. Saturated solutions of these surfactants in CO2 and 23 C and 1000 -2500 psia were tested in the high pressure viscometer, with and without water present. However, none of these saturated solutions or a solution of CO2 and Aerosol OT, which is known to form reverse micelles in supercritical light alkane systems, (15) resulted in viscosity increases relative to pure CO2. It must be noted that experimental verification of reverse micelle formation was not performed. This method of increasing the CO2 viscosity was not pursued because we felt that (1) the low viscosity of the continuous phase, CO2, would not promote the formation of viscous, micellar solutions, and (2) the surfactants listed in Table II were the most likely to satisfy our requirements. Their inability to increase the viscosity of 002 whether micelles formed or not, did not lead us to believe other surfactants would yield dramatically better results.

Jimenez-Carmona, M. M. and Luque de Castro, M. D., Reverse-micelle formation a strategy for enhancing C02-supercritical fluid extraction of polar analytes. Anal. Chim. Acta, 358, 1-4, 1998. 

ZHA Zhang, R., Liu, J., Han, B., Wang, B., Sun, D., and He, J., Effect of PEO-PPO-PEO stmcture on the compressed ethylene-induced reverse micelle formation and water... 

Let us now discuss the structure of a reverse micelle. As the name suggests it has a structural arrangement exactly opposite to that of a micelle. Reverse micelles generally refer to aggregates of surficants (e.g., dioctyl sulfosuccinate, AOT) formed in a non-polar solvent. In this situation, the polar headgroups of the surficants point inward (core) and the hydrocarbon chains project outward into the non-polar solvent [3]. The solvent one uses for reverse micelle formation is usually liquid hydrocarbons. Recently the formation of reverse micelles in supercritical fluids such as ethane, propane, and carbon dioxide has been observed. 

Completely anhydrous reverse micelles are difficult to obtain. The uptake of even a relatively small number of water molecules may strongly facilitate reverse micelle formation by favorable hydration of the polar groups. Further solubilization of water in the core of the reverse micelles causes an increase of the size of the aggregate. Such systems approach the domain of microemulsions, which are discussed in Section 11.8. 

Scriano NU Jr, Venditti R, Saquing CD, Bushey D, Argyropoulos DS. Solubdizing amino acids and polypeptides in supercritical CO2 via reverse micelle formation. Colloids Surf A 2008 315 110-6. 

Guo C, Liu HZ, Chen JY (2000) A fourier transform infrared study on water-induced reverse micelle formation of block copoly(oxyethylene-oxypropylene-oxyethylene) in OTganic solvent. Colloids Surf A 175 193-202... 

At the inner phase, BSA provides a mechanical barrier to the release of small molecules from the internal interface. The release proceeds mainly via reverse micellar transport. The presence of BSA reduces the chance of reverse micelle formation and thus decreases the release rate of entrapped addenda within the emulsion droplets. 

Rai R, Pandey S, Baker SN, Vora S, Behera K, Baker GA, Pandey S (2012) Ethanol-Assisted, Few Nanometer, Water-ln-lomc-Liquid Reverse Micelle Formation by a Zwitterionic Surfactant. Chemistry-a European Journal 18 (39) 12213-12217. doi 10.1002/chem.201200682... 

A. (1994) Study of aerosol OT reverse micelle formation by infrared spectroscopy. J. Phys. Chem., 98,... 

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