title: Small-angle X-ray scattering insights into the architecture-dependent emulsifying properties of amphiphilic copolymers in supercritical carbon dioxide.
abstract: The supramolecular assembly of a series of copolymers combining poly(ethylene oxide)-rich hydrophilic and fluorinated CO2-philic sequences is analyzed by synchrotron small-angle X-ray scattering (SAXS) in supercritical CO2, as well as in water/CO2 emulsions. These copolymers were designed to have the same molecular weight and composition and to differ only by their macromolecular architecture. The investigated copolymers have random, block, and palm-tree architectures. Besides, thermoresponsive copolymer is also analyzed, having a hydrophilic sequence becoming water-insoluble around 41 °C, i.e., just above the critical point of CO2. At the length scale investigated by SAXS, only the random copolymer appears to self-assemble in pure CO2, in the form of a disordered microgel-like network. The random, block, and thermoresponsive copolymers are all able to stabilize water/CO2 emulsions but not the copolymer with the palm-tree architecture, pointing at the importance of macromolecular architecture for the emulsifying properties. A modeling of the SAXS data shows that the block and the thermoresponsive copolymers form spherical micelle-like structures containing about 70% water and 30% polymer.
authors.affiliation: Center for Education and Research on Macromolecules (CERM), University of Liège , B6a, Sart-Tilman, B-4000 Liège, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: Alaimo
authors.forename: Daniel
authors.initials: D
authors.lastname: Hermida Merino
authors.forename: Bruno
authors.initials: B
authors.lastname: Grignard
authors.forename: Wim
authors.initials: W
authors.lastname: Bras
authors.forename: Christine
authors.initials: C
authors.lastname: Jérôme
authors.forename: Antoine
authors.initials: A
authors.lastname: Debuigne
authors.forename: Cedric J
authors.initials: CJ
authors.lastname: Gommes