title: Study of nano-emulsion formation by dilution of microemulsions.
abstract: The influence of different dilution procedures on the properties of oil-in-water (O/W) nano-emulsions obtained by dilution of oil-in-water (O/W) and water-in-oil (W/O) microemulsions has been studied. The system water/SDS/cosurfactant/dodecane with either hexanol or pentanol as cosurfactant was chosen as model system. The dilution procedures consisted of adding water (or microemulsion) stepwise or at once over a microemulsion (or water). Starting emulsification from O/W microemulsions, nano-emulsions with droplet diameters of 20 nm are obtained, independently on the microemulsion composition and the dilution procedure used. In contrast, starting emulsification from W/O microemulsions, nano-emulsions are only obtained if the emulsification conditions allow reaching the equilibrium in an O/W microemulsion domain during the process. These conditions are achieved by stepwise addition of water over W/O microemulsions with O/S ratios at which a direct microemulsion domain is crossed during emulsification. The nature of the alcohol used as cosurfactant has been found to play a key role on the properties of the nano-emulsions obtained: nano-emulsions in the system using hexanol as cosurfactant are smaller in size, lower in polydispersity, and have a higher stability than those with pentanol.
authors.affiliation: Departament d'Enginyeria Química, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona, Spain. isabelsolefont@hotmail.com
authors.forename: I
authors.initials: I
authors.lastname: Solè
authors.forename: C
authors.initials: C
authors.lastname: Solans
authors.forename: A
authors.initials: A
authors.lastname: Maestro
authors.forename: C
authors.initials: C
authors.lastname: González
authors.forename: J M
authors.initials: JM
authors.lastname: Gutiérrez
mesh_terms: D000473:Alkanes / Q000737:chemistry; D004655:Emulsions / Q000737:chemistry*; D000441:Hexanols / Q000737:chemistry; D009821:Oils / Q000737:chemistry*; D000439:Pentanols / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D000473:Alkanes; D004655:Emulsions; D000441:Hexanols; D009821:Oils; D000439:Pentanols; D013501:Surface-Active Agents; D014867:Water; C007548:n-dodecane; D012967:Sodium Dodecyl Sulfate