281107 Cosurfactant Leads to Successful Dilute Emulsion Formation Via Microemulsion

Thursday, November 1, 2012: 9:35 AM
412 (Convention Center )
Hanseung Lee1, Eric Morrison2 and Alon V. McCormick1, (1)Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, (2)Ecolab, Eagan, MN

Cosurfactants play an important role in self-emulsification in three-component systems (water, oil, and non-ionic surfactant). The addition of a very small amount of cosurfactant can abruptly change the interfacial tension and curvature. It can determine the region of composition/temperature producing stable microemulsions. Such one-phase microemulsions have been known to serve as useful precursors to nanoemulsions – dilute long-lived emulsions of nanoscale droplete.

Here, we create very stable vesicular structures from the microemulsions; we found that a sufficient amount of cosurfactant determines the success of microemulsion processing. We have investigated the phase behavior of water/n-hexadecane/nonylphenol ethoxylates system and created kinetically stable nanoparticles.

To study this, we use three complementary methods: cryogenic transmission electron microscopy (Cryo-TEM), cryogenic scanning electron microscopy (Cryo-SEM), and freeze-fracture electron-beam evaporated replicate TEM (FF-TEM).  The complementary use of these techniques shows the behavior of these complex fluid microstructure transitions at multiple scales.  Cryo-TEM alone cannot show crucial, large-scale structures, but cryo-SEM can. Cryo-SEM alone cannot show where the oil is, but FF-TEM can.

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See more of this Session: Emulsions and Foams I
See more of this Group/Topical: Engineering Sciences and Fundamentals