Phase Behavior of Binary and Ternary Mixtures of Poly(decyl acrylate)-Supercritical Solvents-Decyl Acrylate and Poly(decyl methacrylate)-CO2-Decyl Methacrylate Systems

Experimental cloud-point data up to 205 °C and 2300 bar are measured for binary and ternary mixtures of poly(decyl acrylate) [poly (DA)]-supercritical solvents-decyl acrylate (DA) and poly(decyl methacrylate) [poly(DMA)]-CO2-decyl methacrylate (DMA). Also, the cloud-point curves show the binary mixtures for poly(DA) in supercritical CO2, propane, propylene, butane, 1-butene, and dimethyl ether (DME). The phase behaviors for the poly(DMA)-CO2-DMA system are measured in changes of the pressure-temperature (P-T) slope and with DMA concentrations of 4.4, 6.7, 11.2, 22.8, and 32.9 wt %. Adding 41.6 wt % DMA to the poly(DMA)-CO2 solution significantly changes the phase behavior; the curves take on the appearance of a typical LCST boundary. The cloud-point curves for the poly(DA) -CO2 system with 0, 7.5, 14.9, 23.4, and 34.9 wt % DA changes the P-T curve from an upper critical solution temperature (UCST) region to a lower critical solution temperature (LCST) region as the decyl acrylate concentration increases. Adding 40.2 wt % DA to the poly (DA)-CO2 solution significantly changes the phase behavior. The cloud-point curve takes on the appearance of a typical lower LCST region. High-pressure phase behavior data are obtained for the CO2-DA and CO2-DMA systems at temperatures in the range 40-120 °C and pressures up to 189 bar. The CO2-DA and CO2-DMA systems exhibit type-I phase behavior with a continuous mixture-critical curve. The experimental results for the CO2-DA and CO2-DMA mixtures are modeled using the Peng-Robinson equation of state. A good fit of the data is obtained from the Peng-Robinson equation of state using two adjustable parameters for CO2-DA and CO2-DMA systems.