Phase behavior on the binary and ternary mixtures of poly(cyclohexyl acrylate) and poly(cyclohexyl methacrylate) in supercritical CO₂

Abstract

High-pressure phase behavior was measured for the CO 2 -cyclohexyl acrylate and CO 2 -cyclohexyl methacrylate system at 40, 60, 80, 100, and 120°C and pressure up to 206 bar. This system exhibits type I phase behavior with a continuous mixture-critical curve. The experimental results for the CO 2 -cyclohexyl acrylate and CO 2 -cyclohexyl methacrylate system were modeled using the Peng-Robinson equation of state. Experimental cloud-point data, at a temperature of 250°C and pressure of 2800 bar, were presented for ternary mixtures of poly(cyclohexyl acrylate)-CO 2 -cyclohexyl acrylate and poly(cyclohexyl methacrylate)-CO 2 -cyclohexyl methacrylate systems. Cloud-point pressures of poly(cyclohexyl acrylate)-CO 2 -cyclohexyl acrylate system were measured in the temperature range of 40 to 180°C and at pressures as high as 2200 bar with cyclohexyl acrylate concentrations of 22.5, 27.4, 33.2, and 39.2 wt %. Results showed that adding 45.6 wt % cyclohexyl acrylate to the poly(cyclohexyl acrylate)-CO 2 mixture significantly changes the phase behavior. This system changed the pressure-temperature slope of the phase behavior curves from the upper critical solution temperature (UCST) region to the lower critical solution temperature (LCST) region with increasing cyclohexyl acrylate concentration. Poly(cyclohexyl acrylate) did not dissolve in pure CO 2 at a temperature of 250°C and pressure of 2800 bar. Also, the ternary poly(cyclohexyl methacrylate)-CO 2 -cyclohexyl methacrylate system was measured below 187°C and 2230 bar, and with cosolvent of 27.4 -46.7 wt %. Poly-(cyclohexyl methacrylate) did not dissolve in pure CO 2 at 240°C and 2500 bar. Also, when 53.5 wt % cyclohexyl methacrylate was added to the poly(cyclohexyl methacrylate)-CO 2 solution, the cloud-point curve showed the typical appearance of the LCST boundary.

Structure–Property Relationships in CO2-philic (Co)polymers: Phase Behavior, Self-Assembly, and Stabilization of Water/CO2 Emulsions

“…This may be due to the domination of dispersion forces at higher temperatures. These side chain length trends were further investigated in different studies focusing on poly­(alkyl acrylates), such as poly­(propyl acrylate), poly­(hydroxypropyl acrylate), poly­(hexyl acrylate), poly­(cyclohexyl acrylate), poly­(2-ethylhexyl acrylate), poly­(isooctyl acrylate), poly­(decyl acrylate), poly­(dodecyl acrylate), and poly­(octadecyl acrylate) …”

“…This may be due to the domination of dispersion forces at higher temperatures. These side chain length trends were further investigated in different studies focusing on poly(alkyl acrylates), 169 such as poly(propyl acrylate), 170 poly(hydroxypropyl acrylate), 171 poly(hexyl acrylate), 172 poly(cyclohexyl acrylate), 173 poly(2-ethylhexyl acrylate), 174 poly(isooctyl acrylate), 175 poly(decyl acrylate), 176 poly(dodecyl acrylate), 177 and poly(octadecyl acrylate). 178 Poly(acrylates) with ether groups in their side chain such as poly(2-(2-ethoxyethoxy)ethyl acrylate 179 and poly(2-butoxyethyl acrylate) 180 were also examined.…”

“…The reduced solubility of poly(methacrylates) was attributed to the decreased entropy of mixing and the lesser flexibility of the polymer chains. Other investigations on poly(alkyl methacrylates) covered poly(neopentyl methacrylate), 181 poly(hexyl methacrylate), 172 poly(cyclohexyl methacrylate), 173 poly(2-ethylhexyl methacrylate), 174 poly(isooctyl acrylate), 175 poly(decyl methacrylate), 176 poly(isodecyl methacrylate), 182 and poly(isobornyl methacrylate). 183 3.3.3.2.…”

Dispersibility of Poly(vinyl acetate) Modified Silica Nanoparticles in Carbon Dioxide with Several Cosolvents

“…As discussed in the Introduction, some cosolvents need to be added in the (PVAc + CO 2 ) system to shift the transition point curve at relatively low temperatures and pressures. 36 Zhu et al 44 proposed that the addition of ethanol, acetic acid, and ethyl acetate to PVAc + CO 2 can shift the cloud point curve to lower pressures, indicating that these three compounds are good cosolvents for the PVAc + CO 2 system. Ethanol shows the best character as a cosolvent to increase the solubility of PVAc in CO 2 .…”

Cosolvent effect on the phase behavior for the poly(benzyl acrylate) and poly(benzyl methacrylate) in supercritical carbon dioxide and dimethyl ether

“…Phase behavior data for polymer-supercritical fluids systems are required for efficient operation and plant design of supercritical fluid polymer processes. We have demonstrated that it is possible to dissolve poly(acrylate) and poly(methacrylate) in SCF solvents over a wide range of temperature at high pressure if an acrylate and methacrylate monomer are used as cosolvents [6,7]. The cosolvent can enhance high molecular weight polymer solubility in a given solvent due to several reasons.…”