Experimental cloud-point data up to 478 K and 248.0 MPa are reported for binary and ternary mixtures of poly(2-ethylhexyl methacrylate) + carbon dioxide + 2-ethylhexyl methacrylate and poly(2-ethylhexyl acrylate) + carbon dioxide + 2-ethylhexyl acrylate systems. High-pressure cloud-point data are also reported for poly(2-ethylhexyl methacrylate) and poly(2-ethylhexyl acrylate) in supercritical propane, propylene, butane, 1-butene, dimethyl ether and CHClF2. Cloud-point behavior for the poly(2-ethylhexyl methacrylate) + carbon dioxide + 2-ethylhexyl methacrylate system were measured in changes of the pressure-temperature (p - T) slope and with 2-ethylhexyl methacrylate weight fraction of 0.0 wt.%, 20.1 wt.%, 30.3 wt.%, and 56.4 wt.%. With 66.6 wt.% 2-ethylhexyl methacrylate to the poly(2-ethylhexyl methacrylate) + carbon dioxide solution, the cloud-point curves take on the appearance of a typical lower critical solution temperature boundary, and cloud-point, liquid-vapor and liquid-liquid-vapor points exhibited in the phase behavior curve. The poly(2-ethylhexyl acrylate) + carbon dioxide + 0.0 wt.%, 9.7 wt.%, 20.6 wt.%, 40.9 wt.%, 55.2 wt.%, and 60.4 wt.% 2-ethylhexyl acrylate systems change the pressure-temperature (p - T) curve from upper critical solution temperature region to lower critical solution temperature (LCST) region as the 2-ethylhexyl acrylate weight fraction increases. For 70.9 wt.% 2-ethylhexyl acrylate, the poly(2-ethylhexyl acrylate) + carbon dioxide solution significantly changes the phase behavior. Also, the impact of dimethyl ether weight fraction for the poly(2-ethylhexyl methacrylate) and poly(2-ethylhexyl acrylate) + carbon dioxide + dimethyl ether system is measured at temperatures to 455.0 K and a pressure range of (4.3 ~ 248.0) MPa. Pressure-composition (p - x) isotherms are obtained for the carbon dioxide + 2-ethylhexyl methacrylate systems at (313.15, 333.15, 353.15, 373.15 and 393.15) K and pressure up to 20.5 MPa. The carbon dioxide + 2-ethylhexyl methacrylate systems exhibit type-I phase behavior with a continuous mixture critical curve. The experimental results for carbon dioxide + 2-ethylhexyl methacrylate mixtures are modeled using the Peng-Robinson equation of state (PR EOS) with two adjustable parameters.