title: Stability of Water/Poly(ethylene oxide)43-b-poly(ε-caprolactone)14/Cyclohexanone Emulsions Involves Water Exchange between the Core and the Bulk.
abstract: The formation of emulsions upon reverse self-association of the monodisperse amphiphilic block copolymer poly(ethylene oxide)43-b-poly(ε-caprolactone)14 in cyclohexanone is reported. Such emulsions are not formed in toluene, chloroform, or dichloromethane. We demonstrate by magnetic resonance spectroscopy the active role of the solvent on the stabilization of the emulsions. Cyclohexanone shows high affinity for both blocks, as predicted by the Hansen solubility parameters, so that the copolymer chains are fully dissolved as monomeric chains. In addition, the solvent is able to produce hydrogen bonding with water molecules. Water undergoes molecular exchange between water molecules associated with the polymer and water molecules associated with the solvent, dynamics of major importance for the stabilization of the emulsions. Association of polymeric chains forming reverse aggregates is induced by water over a concentration threshold of 5 wt %. Reverse copolymer aggregates show submicron average hydrodynamic diameters, as seen by dynamic light scattering, depending on the polymer and water concentration.
authors.affiliation: Departamento de Ciencias de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile , Avenida Tupper 2069, Santiago 8370451, Chile.|Instituto de Ciencias Químicas, Facultad de Ciencias, Universidad Austral de Chile , Las Encinas 220, Valdivia 5110033, Chile.
authors.forename: Mario E
authors.initials: ME
authors.lastname: Flores
authors.affiliation: Departamento de Ciencias de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile , Avenida Tupper 2069, Santiago 8370451, Chile.
authors.forename: Francisco
authors.initials: F
authors.lastname: Martínez
authors.affiliation: Instituto de Ciencias Químicas Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile , El Llano Subercaseaux 2801, Santiago 8320325, Chile.
authors.forename: Andrés F
authors.initials: AF
authors.lastname: Olea
authors.forename: Toshimichi
authors.initials: T
authors.lastname: Shibue
authors.forename: Natsuhiko
authors.initials: N
authors.lastname: Sugimura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nishide
authors.affiliation: Instituto de Ciencias Químicas, Facultad de Ciencias, Universidad Austral de Chile , Las Encinas 220, Valdivia 5110033, Chile.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Moreno-Villoslada