Experimental cloud-point data to the temperature of 180 degrees C and the pressure up to 2000 bar are presented for ternary mixtures of poly(isooctyl acrylate) + supercritical fluid solvents + isooctyl acrylate systems. Cloud-point pressures of poly(isooctyl acrylate) + CO2 + isooctyl acrylate system is measured in the temperature range of 60-180 degrees C and to pressures as high as 2000 bar with isooctyl acrylate concentration of 0-44.5 wt. This system changes the pressure-temperature slope of the phase behavior curves from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region as the isooctyl acrylate concentration increases. Poly(isooctyl acrylate) does dissolve in pure CO2 to the temperature of 180 degrees C and the pressure of 2000 bar. The phase behavior for poly(isooctyl acrylate) + CO2 + 9.51 14.8, 30.6, and 41.9 wt % dimethyl ether (DME) mixture show the curve changes from UCST to LCST as the DME concentration increases. Also, the cloud-point curves are measured for the binary mixtures of poly(isooctyl acrylate) in supercritical propane, propylene, butane, and 1-butene. High pressure phase behaviors are measured for the CO2 + isooctyl acrylate system at 40, 60, 80, 100, and 120 degrees C and pressure up to 200 bar. This system exhibits type-I phase behavior with a continuous mixture-critical curve. The experimental results for the CO2 + isooctyl acrylate system are modeled using the Peng-Robinson equation of state. (C) 2007 Wiley Periodicals, Inc.