Stability of Water/Poly(ethylene oxide)(43)-b-poly(epsilon-caprolactone)(14)/Cyclohexanone Emulsions Involves Water Exchange between the Core and the Bulk

作者：Flores Mario E; Martinez Francisco; Olea Andres F; Shibue Toshimichi; Sugimura Natsuhiko; Nishide Hiroyuki; Moreno Villoslada Ignacio^*

来源：Journal of Physical Chemistry B, 2015, 119(52): 15929-15937.

DOI：10.1021/acs.jpcb.5b10274

The formation of emulsions upon reverse self-association of the monodisperse amphiphilic block copolymer poly(ethylene oxide)(43)-b-poly(epsilon-caprolactone)(14) in cydohexanone 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.

• 出版日期2015-12-31