Morphology control of poly[2-(perfluorooctyl)ethyl acrylate-co-tert-butyl acrylate] by pressure in supercritical carbon dioxide

Abstract

The morphology control was attained in supercritical carbon dioxide (scCO2) for poly[2-(perfluorooctyl)ethyl acrylate (POA)-co-tert-butyl acrylate (TBA)] random copolymers with POA/TBA molar ratios of 9:1, 8:2, 7:3, 6:4, 5:5, and 4:6. The copolymers showed a different solubility and morphology in scCO2 depending on the POA/TBA ratio. There was a tendency that the copolymers with a lower TBA content, such as 9:1, 8:2, and 7:3, showed a higher solubility in scCO2 and formed a fiber-like structure in the heterogeneous state below their cloud point. On the other hand, the copolymers with the higher TBA contents of 6:4, 5:5, and 4:6 provided micrometer-sized spherical particles. Furthermore, the morphology was controlled by the CO2 pressure because the fiber-like morphology for the copolymer with the 6:4 ratio changed to spherical by decreasing the CO2 pressure.