High pressure phase behavior of poly[isopropyl acrylate] and poly[isopropyl methacrylate] in supercritical fluid (SCF) solvent and SCF solvent + cosolvent mixtures

Cloud-point data are reported for poly(isopropyl acrylate) [P(IPA)] in CO2, propane, propylene, butane, 1-butene, and dimethyl ether (DME) and for poly(isopropyl methacrylate) [P(IPMA)] in CO2. P(IPA) + alkene cloud-point curves are ∼100 °C lower than the P(IPA) + alkane curves, which are close to the P(IPA) + CO2 curve located at temperatures greater than 130 °C and pressures of 2500 bar. P(IPA) dissolves in pure DME at conditions as mild as 50 °C and 200 bar. Since IPA and IPMA monomers are used as cosolvents with CO2, binary IPA + CO2 and IPMA + CO2 data are reported to complement the ternary cloud-point data. Both monomer + CO2 mixtures exhibit type-I behavior and both are adequately modeled with the Peng–Robinson equation of state. IPMA is a more effective cosolvent than IPA. The polymer + CO2 + monomer phase behavior suggests that it is viable to polymerize IPA or IPMA in CO2 at moderate operating conditions.