The
supramolecular assembly of a series of copolymers combining
poly(ethylene oxide)-rich hydrophilic and fluorinated CO<sub>2</sub>-philic sequences is analyzed by synchrotron small-angle X-ray scattering
(SAXS) in supercritical CO<sub>2</sub>, as well as in water/CO<sub>2</sub> 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 CO<sub>2</sub>.
At the length scale investigated by SAXS, only the random copolymer
appears to self-assemble in pure CO<sub>2</sub>, in the form of a
disordered microgel-like network. The random, block, and thermoresponsive
copolymers are all able to stabilize water/CO<sub>2</sub> 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