Nanostructured Microemulsion Phase Behavior Using AOT or Extended Surfactant Combined with a Cationic Hydrotrope

Khalid Kanan, Hala Yousef, Ibrahim Kayali

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DOI: 10.4236/jsemat.2012.21010                

Abstract

The phase behavior for systems containing sodium bis (2-ethylhexyl sulfosuccinate) (AOT), with the cationic hydro-trope tetraethyl ammonium chloride (TEAC), in the presence of water and heptane were studied. Formulations of mi-croemulsion for such systems and for systems containing the so called “extended surfactant” were carried out at different salt concentrations. Anisotropy was detected using cross polarizers and polarized microscopy. Ultralow interfacial tension for microemulsion was measured, first theoretically using the Chun-Huh equation, and then experimentally using spinning drop experiments. The presence of short chain hydrotropes (TEAC) was found to destabilize the liquid crystalline region, observed in the AOT/water/heptane phase diagram. Ultralow interfacial tensions were observed for microemulsions formulated with surfactant concentrations as low as 0.5%, for both AOT and “extended surfactant” systems. The effect of temperature on the phase behavior of a microemulsion formed with AOT system was studied and found to behave in an opposite manner compared to the nonionic surfactant.

Keywords

Middle Phase Microemulsion; Cationic Hydrotrope; Ultra Low Interfacial Tension

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	J. H. Harwell, D. A. Sabatini and R. C. Knox, “Surfactants for Ground Water Remediation,” Colloids and Surfaces A: Physi-cochemical and Engineering Aspects, Vol. 151, No. 1, 1999, pp. 255-268.
[2]	V. Dwarakanath and G. A. Pope, “Surfactant Phase Behavior with Field Degreasing Solvent,” Environmental Science & Technology, Vol. 34, No. 22, 2000. pp. 4842- 4848. doi:10.1021/es0009121
[3]	S. Heuschkel, A. Goebe and R. Neubert, “Microemulsions—Modern Colloidal Carrier for Dermal and Transdermal Drug Delivery,” Journal of Pharma-ceutical Sciences, Vol. 97, No. 2, 2008, pp. 603-631.
[4]	B. J. Shiau, D. A. Sabatini, J. H. Harwell and D. Q. Vi, “Microemul-sion of Mixed Chlorinated Solvents Using Food Grade (Edible) Surfactants,” Environmental Science & Technology, Vol. 30, No. 1, 1995, pp. 97-103. doi:10.1021/es9501169
[5]	K. Shinoda and H. Kunieda, “The Effect of Salt Concentration, Temperature, and Additives on the Solvent Property of Aerosol OT Solution,” Journal of Colloid and Interface Science, Vol. 118, No. 2, 1987, pp. 586-589.
[6]	E. Marques, A. Khan, M. Miguel and B. Lind-man, “Self-Assembly in Mixtures of a Cationic and an Anionic Surfactant: The Sodium Dodecyl Sulfate-Didodecyldime- thy-lammonium Bromide-Water System,” Journal of Physical Che-mistry, Vol. 97, No. 18, 1993, pp. 4729-4736. doi:10.1021/j100120a028
[7]	A. Unadhyaya, E. J. Acosta, J. F. Scamehron and D. A. Sabatini, “Microemulsion Phase Behavior of Anionic- Cationic Surfactant Mixtures: Effect of Tail Branching,” Journal of Surfactants and Detergents, Vol. 9, No. 4, 2006, pp. 169-179.
[8]	A. Witthyapanyanon, E. J. Acosta, J. H. Harwell and D. A. Sabatini, “Formulation of Ultralow Inter-facial Tension Systems Using Extended Surfactants,” Journal of Surfactants and Detergents, Vol. 9, No. 4, 2006, pp. 331-339. doi:10.1007/s11743-006-5011-2
[9]	I. Kayali, K. Qamhieh and U. Olsson, “Microemulsion Phase Behavior of Aerosol-OT Combined with a Cationic Hydrotrope in the Dilute Region,” Journal of Dispersion Science and Technology, Vol. 31, No. 2, 2010, pp. 183- 187. doi:10.1080/01932690903110293
[10]	C. Huh, “Interfacial Tensions and Solubilizing Ability of a Mi-croemulsion Phase That Coexists with Oil and Brine,” Journal of Colloid and Interface Science, Vol. 71, No. 2, 1979, pp. 408-426.
[11]	P. G. Petrov, S. V. Ahir and E. M. Terentjev, “Rheology at the Phase Transition Boundary: 1. Lamellar L-Alpha Phase of AOT Surfactant Solution,” Langmuir, Vol. 18, No. 24, 2002, pp. 9133-9139.
[12]	Y. Luan, G. Xu, G. Dai, Z. Sun and H. Liang, “The Interaction between Poly(Vinylpyrrolidone) and Reversed Micelles of Wa-ter/AOT/n-Heptane,” Colloid and Polymer Science, Vol. 282, No. 2, 2003, pp. 110-118. doi:10.1007/s00396-003-0900-7
[13]	S. Liu, D. L. Zhang, W. Yan, et al., “Favorable Attributes of Alka-line-Surfactant-Polymer Flooding,” SPE Journal, Vol. 13, No. 1, 2008, pp. 5-16. doi:10.2118/99744-PA
[14]	B. Vonnegut, “Rotating Bubble Method for the Determination of Surface and Interfacial Tensions,” Review of Scientific Instruments, Vol. 13, No. 1, 1942, pp. 6-9. doi:10.1063/1.1769926
[15]	I. Kayali, K. Qamhieh and U. Olsson, “Formulating Middle Phase Microemulsions Using Extended Anionic Surfactant Combined with Cationic Hydro-trope,” Journal of Dispersion Science and Technology, Vol. 32, 2011, pp. 41-46. doi:10.1080/01932690903543303