Effect of the octadecyl acrylate concentration on the phase behavior of poly(octadecyl acrylate)/supercritical CO₂ and C₂H₄ at high pressures

Abstract

Pressure-composition isotherms were measured for the CO 2 /octadecyl acrylate system at 45.0, 80.0, and 100.0°C and at pressures up to 307 bar. This system exhibited type I phase behavior with a continuous mixturecritical curve. The solubility of octadecyl acrylate for the CO 2 /octadecyl acrylate system increased as the temperature increased at a constant pressure. The experimental results for the CO 2 /octadecyl acrylate system were modeled with the Peng-Robinson equation of state. A good fit of the data was obtained with the Peng-Robinson equation of state with one adjustable parameter for the CO 2 /octadecyl acrylate system. Experimental cloud-point data for the poly(octadecyl acrylate)/CO 2 /octadecyl acrylate system were measured from 36 to 193°C and at pressures up to 2100 bar, and the added octadecyl acrylate concentrations were 11.9, 25.9, 28.0, 35.0, and 40.0 wt %. Poly(octadecyl acrylate) dissolved in pure CO 2 up to 250°C and 2100 bar. Also, adding 45.0 wt % octadecyl acrylate to the poly(octadecyl acrylate)/CO 2 solution significantly changed the phase behavior. This system changed the pressure-temperature slope of the phasebehavior curves from an upper critical solution temperature (UCST) region to a lower critical solution temperature region as the octadecyl acrylate concentration increased. Cloud-point data to 150°C and 750 bar were examined for poly(octadecyl acrylate)/C 2 H 4 /octadecyl acrylate mixtures at octadecyl acrylate concentrations of 0.0, 15.0, and 45.0 wt %. The cloud-point curve of the poly(octadecyl acrylate)/ C 2 H 4 system was relatively flat at 730 bar between 41 and 150°C. The cloud-point curves of 15.0 and 45.0 wt % octadecyl acrylate exhibited positive slopes extending to 35°C and approximately 180 bar.

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

“…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. Thus, Byun and coworkers reported the solubility of poly(2-(2-ethoxyethoxy)ethyl acrylate (M w = 100 000 g mol −1 ) in sc-CO 2 .…”

“…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) …”

Microcosmic understanding on thickening capability of copolymers in supercritical carbon dioxide: the key role of π–π stacking

“…The pressure at which the phase change occurred was the cloud point pressure. [38][39][40][41] The cloud point pressure was determined by repeating the three measurements. Viscosity is calculated by eqn (1) 42-52…”

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

“…Figure 1 shows a schematic diagram of the experimental apparatus used for pressure–composition isotherms for the CO 2 –cyclohexyl acrylate and CO 2 –cyclohexyl methacrylate mixtures11, 12 and obtained cloud‐point curves for poly(cyclohexyl acrylate)–CO 2 –cyclohexyl acrylate and poly(cyclohexyl methacrylate)–CO 2 –cyclohexyl methacrylate ternary mixtures 13, 14. The bubble‐point, dew‐point, critical‐point, and cloud‐point curves were obtained with a high‐pressure, variable‐volume cell described in detail elsewhere 13–16. Cloud‐points were measured for the polymer solutions at a fixed poly(cyclohexyl acrylate) and poly(cyclohexyl methacrylate) concentration of 5.0 ± 0.5 wt %, which is typical of the concentrations used for polymer–SCF solvent studies 17.…”