The cloud-point behavior of fluorinated polyisoprenes (FPI) and fluorinated polybutadienes (FPBD) in supercritical fluid (SCF) CO2 are reported at temperatures from 60 to 170 °C and pressures from 1000 to 3000 bar. These fluorinated polymers were prepared by the addition of difluorocarbene (CF2) to the parent polydienes yielding a gem-difluorocyclopropane repeating unit, a segment containing both fluorine and a significant dipole moment. Neither the unmodified polyisoprene starting material nor the hydrogenated variant dissolves in CO2 up to temperatures of 155 °C and pressures of 2600 bar. Both FPI and FPBD dissolve in CO2, but pressures in excess of 1000 bar are needed to obtain a single phase. The PFI and PFBD cloud-point curves exhibit temperature minima at approximately 60 and 80 °C, respectively, likely due to an increase in CO2-CO2 and polymer-polymer interactions relative to polymer-CO2 interactions. As the amount of CF2 incorporation in FPI samples decreases, the cloudpoint curves shift to higher pressures and to higher temperatures. In a series of FPBD samples, an increase in cloud-point pressure with increase in molecular weight is initially large for molecular weights less than 10 5 and then becomes much less at higher molecular weights, as also observed for other polymer-SCF solvent mixtures. This methodology for incorporation of fluorine into macromolecules leads to significant enhancement of solubility in CO2.

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