title: Stable surfactant-free toluene-polyethylene-in-water emulsion prepared by ultrasonication at high temperature.
abstract: A toluene-polyethylene (PE) mixture, only partially miscible at room temperature (RT), was ultrasonically dispersed in hot water, followed by immediate cooling to give a highly stable surfactant-free oil-in-water (O/W) emulsion. This temperature effect was correlated with physical gelation of the bulk mixture. Prolonged stabilization was achieved only through dispersion at a temperature (T(d)) above the gelation temperature (T(gel)) of the toluene-low-density PE (LDPE) mixture and subsequent rapid cooling. These stabilized emulsions exhibited characteristics such as a small droplet size with a narrow size distribution, low ζ-potential, and round-shaped droplets, which were not observed for the emulsions prepared at T(d) < T(gel) or those at T(d) > T(gel) that had been subjected to slow cooling. From these results, physical gelation through crystallization and modification of the droplet surface by PE were concluded to be essential for the prolonged stability of a surfactant-free toluene emulsion.
authors.affiliation: Department of Pure and Applied Chemistry, Tokyo University of Science, Japan. hisakai@rs.noda.tus.ac.jp
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakai
authors.forename: Keiji
authors.initials: K
authors.lastname: Kamogawa
authors.forename: Toshio
authors.initials: T
authors.lastname: Sakai
authors.forename: Taeko
authors.initials: T
authors.lastname: Umeda
authors.forename: Atsutoshi
authors.initials: A
authors.lastname: Matsumura
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sakai
authors.forename: Masahiko
authors.initials: M
authors.lastname: Abe
mesh_terms: D004655:Emulsions / Q000138:chemical synthesis / Q000737:chemistry; D020959:Polyethylene / Q000737:chemistry*; D013696:Temperature; D014050:Toluene / Q000737:chemistry*; D014465:Ultrasonics; D014867:Water / Q000737:chemistry*
chemical_list: D004655:Emulsions; D014867:Water; D014050:Toluene; D020959:Polyethylene