title: Cryogenic transmission electron microscopy study: preparation of vesicular dispersions by quenching microemulsions.
abstract: We previously showed that long-lived nanoemulsions, seeming initially vesicular, might be prepared simply by diluting and cooling (quenching) warm microemulsions with n-hexadecane with precooled water. In this paper, we confirm that these systems are vesicular dispersions when fresh, and they can be made with similar structures and compositional dependence using alkanes with chain lengths ranging from octane to hexadecane. The nanostructures of fresh nanoemulsions are imaged with cryogenic transmission electron microscopy (cryo-TEM). We confirm that water-continuous microemulsions give simple dispersions of vesicles (sometimes unilamellar), typically less than 100 nm in diameter; these systems can avoid separation for over 2 months. Selected samples were also prepared using halogenated alkanes to create additional contrast in the cryo-TEM, allowing us to confirm that the oil is located in the observed vesicular structures.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, U.S.A.
authors.forename: H S
authors.initials: HS
authors.lastname: Lee
authors.affiliation: Ecolab Food and Beverage Division, Eagan, Minnesota, U.S.A.
authors.forename: E D
authors.initials: ED
authors.lastname: Morrison
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, U.S.A.
authors.forename: Q
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, U.S.A.
authors.forename: A V
authors.initials: AV
authors.lastname: McCormick
keywords: Conductivity; DLS; confocal Raman microscopy; cryo-TEM; microemulsions; phase change emulsification