Monomer concentration effect on the phase behavior of poly(propyl acrylate) and poly(propyl methacrylate) with supercritical CO2 and C2H4

Experimental cloud-point data to temperature of 186degreesC and pressure of similar to2,500 bar are presented for ternary mixtures of poly(propyl acrylate)(PPA)-CO2-propyl acrylate (PA) PPA-C2H4-PA and poly(propyl methacrylate) (PPMA)-CO2 propyl methacrylate (PMA) systems. Cloud-point pressures of PPA-CO2-PA system were measured in the temperature range of 32degreesC to 175degreesC and to pressures as high as 2,070 bar with PA concentrations of 0.0, 5.0, 11.7 and 30.4 wt%. Adding 34.1 wt% PA to the PPA-CO2 mixture significantly changes the phase behavior. This system changes the pressure-temperature slope of the phase behavior curves from U-LCST region to LCST region as the PA concentration increases. Cloud-point data to 170degreesC and 1,400 bar are presented for PPA-C2H4-PA mixtures and with PA concentration of 0.0, 5.7, 15.5 and 22.2 wt%. The cloud-point curve of PPA-C2H4 system shows relatively flat at 730 bar for temperatures between 41 and 150degreesC. With 15.5 and 22.2 wt% PA the cloud-point curve exhibits a positive slope that extends to 35degreesC and similar to180 bar. Also, the ternary PPMA-CO2-PMA system was measured below 186degreesC and 2,484 bar, and with cosolvent of 5.2-20.1 wt%. PPMA does not dissolve in pure CO2 to 233degreesC and 2,500 bar. Also, when 41.5 wt% PMA is added to the PPMA-CO2 solution, the cloud-point curve shows the typical appearance of a lower critical solution temperature (LCST) boundary.