Microemulsions, polyethylene glycol

W. T. Osterloh and M. J. Jante, Jr. Surfactant-polymer flooding with anionic PO/EO surfactant microemulsions containing polyethylene glycol additives. In Proceedings Volume, volume 1, pages 485 94. 8th SPE/DOE Enhanced Oil Recovery Symp (Tulsa, OK, 4/22-4/24), 1992. 

Li N, Zhang S, Li X et al (2009) Effect of polyethylene glycol (PEG-400) on the l-butyl-3-methylimidazolium tetrafluoroborate-in-cyclohexane ionic liquid microemulsion. Colloid Polym Sci 287(1) 103-108... 

Aboofazeli, R., Lawrence, C. B., Wicks, S. R., and Lawrence, M. J. (1994), Investigations into the formation and characterization of phospholipid microemulsions. Part 3. Pseudo-ternary phase diagrams of systems containing water-lecithin-isopropyl myristate and either an alkanoic acid, amine, alkanediol, polyethylene glycol alkyl ether or alcohol as cosurfactant, Int. J. Pharm., Ill, 63-72. 

Schtibel, D., Bedford, O.D., Ilgenfritz, G., Eastoe, J. and Heenan R.K. (1999) Oligo- and polyethylene glycols in water-in-oil microemulsions. A SANS study. Phys. Chem. Chem. Phys., 1,2521-2525. 

Miller, D.J. and Henning, T. (2005) Microemulsions containing polyethylene glycol. Tenside Surfactants. Det., 42, 34. 

In addition to w/c microemulsions, o/c microemulsions may be formed for systems with strong surfactant adsorption. The area occupied by PFPE-C00 NH4 at the interface between 600 molecular weight polyethylene glycol (PEG) md CO2 is 440 per molecule based upon measurement of the interfacial tension versus surfactant concentration [21]. This surface coverage is sufficient for microemulsion formation as was verified with phase behavior measurements. Only 0.55 wt% of 600 molecular weight polyethylene glycol is soluble in CO2 at 45 °C and 300 bar. With the addition of 4wt% PFPE-C00 NH4 surfactant, up to 1.8 wt% is solubilized. The additional PEG resides in the core of the microemulsion droplets, consistent with the prediction from the adsorption measurement. 

The third effort in the early development in microemulsion science originated with Saito and Shinoda [18,19] in Japan. In their studies on the temperature-dependent behavior of water-hydrocarbon-polyethylene glycol alkyl (aryl) ether systems, a relationship was observed between the cloud point of the surfactant and the solubilization of the hydrocarbon. For aliphatic hydrocarbons it was found that the solubilization of hydrocarbon... 

There are two additional types of chemical flooding systems that involve surfactants which are briefly mentioned here. One of these systems utilizes surfactant-polymer mixtures. One such study was presented by Osterloh et al. [72] which examined anionic PO/EO surfactant microemulsions containing polyethylene glycol additives adsorbed onto clay. The second type of chemical flood involves the use of sodium bicarbonate. The aim of the research was to demonstrate that the effectiveness of sodium bicarbonate in oil recovery could be enhanced with the addition of surfactant. The surfactant adsorption was conducted in batch studies using kaolinite and Berea sandstone [73]. It was determined that the presence of a low concentration of surfactant was effective in maintaining the alkalinity even after long exposures to reservoir minerals. Also, the presence of the sodium bicarbonate is capable of reducing surfactant adsorption. 

Shiokawa, T., Hattoii, Y., Kawano, K. et al., 2005. Effect of polyethylene glycol tinker chain length of folate-tinked microemulsions loading aclacinomycin A on targeting ability and antitumor effect in vitro and in vivo. Clin Cancer Res. 11 2018-25. 

It is seen above that the areas for microemulsions stabilized by ionic surfactants are decisively dependent on the structure of the cosurfactant to cause the necessary disorder in the system. Microemulsions stabilized by polyethylene glycol adduct nonionic surfactants, on the other hand, are characterized by the fact that co surfactant is not used. Instead, the areas of stability now rely on temperature (Figure 1.11) although the relation with the liquid crystal structure is still the essential element [14]. 

D. Schubel and G. Ilgenfritz 1997 Influence of polyethylene glycols on the percolation behavior of anionic and nonionic w/o microemulsions, Langmuir 13,4246-4250. 

Influence of Polyethylene Glycols and Polyethylene Glycol Dimethyl Ethers upon the Internal Dynamics of Water in Oil Microemulsions... 

We determined the percolation temperature of AOT/isooctane/water microemulsions ([AOT] = 0.5 M and W = 22.2) in the presence of different polyethylene glycols and polyethylene glycol dimethyl ethers concentrations. The obtained results are shown in Figures 4.1 and 4.2, respectively. In all cases, we have observed a decrease in the percolation temperature of the system as the polyethylene glycols and polyethylene glycol dimethyl ethers concentration increases. This behavior is significantly different from that observed with crown ethers, where we had observed [48,49] an increase in the percolation temperature of the system as the crown ether concentration increased, until a maximum value was... 

Hollow siUca nanoparticles can be synthesized under moderate conditions using luminescent CdSe/ZnS nanoparticles, as described by Darbandi et al. [9]. The synthesis is conducted at room temperature within reverse micelles and by way of a modified water-in-oil microemulsion system, where silica is formed from the hydrolysis of TEOS. Here, the silica acts as a host for the CdSe/ZnS nanoparticles while the latter is simultaneously dissolved. The extent of this dissolution is determined by the amount of ammonia aqueous solution used and the reaction time. In a typical synthesis, cyclohexane is added to polyethylene glycol nonylphenyl ether (the surfactant), pre-prepared luminescent CdSe/ZnS nanopartides in chloroform, and TEOS, and the mixture then stirred vigorously to form the microemulsion. After 30 min, aqueous ammonia is added to initiate the encapsulation, and the reaction is then left overnight at room temperature before the nanopartides are precipitated. By increasing the amount of ammonia used, the core particles become increasingly dissolved to the point where hollow spheres can be obtained (250 (xl ammonia solution). Similarly, an increase in the duration of the reaction will yield nanopartides with increasingly dissolved cores. 

Fig. 7. Chemical structures of IL (benzylpyridinium bis(trifluoromethanesulfonyl) imide, bnPyrNTf2), surfactant (polyethylene glycol p-(l,l,3,3-tetramethylbutyl)-phenyl ether, TX-lOO) and oil (toluene) used to study the formation of microemulsions.

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